Tag: Flumazenil

What is Bretazenil?

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Introduction

Bretazenil (Ro16-6028) is an imidazopyrrolobenzodiazepine anxiolytic drug which is derived from the benzodiazepine family, and was invented in 1988.

It is most closely related in structure to the GABA antagonist flumazenil, although its effects are somewhat different. It is classified as a high-potency benzodiazepine due to its high affinity binding to benzodiazepine binding sites where it acts as a partial agonist. Its profile as a partial agonist and preclinical trial data suggests that it may have a reduced adverse effect profile. In particular bretazenil has been proposed to cause a less strong development of tolerance and withdrawal syndrome. Bretazenil differs from traditional 1,4-benzodiazepines by being a partial agonist and because it binds to α1, α2, α3, α4, α5 and α6 subunit containing GABAA receptor benzodiazepine receptor complexes. 1,4-benzodiazepines bind only to α1, α2, α3 and α5 GABAA benzodiazepine receptor complexes.

Brief History

Bretazenil was originally developed as an anti-anxiety drug and has been studied for its use as an anticonvulsant but has never commercialised. It is a partial agonist for GABAA receptors in the brain. David Nutt from the University of Bristol has suggested bretazenil as a possible base from which to make a better social drug, as it displays several of the positive effects of alcohol intoxication such as relaxation and sociability, but without the bad effects such as aggression, amnesia, nausea, loss of coordination, liver disease and brain damage. The effects of bretazenil can also be quickly reversed by the action of flumazenil, which is used as an antidote to benzodiazepine overdose, in contrast to alcohol for which there is no effective and reliable antidote.

Traditional benzodiazepines are associated with side effects such as drowsiness, physical dependence and abuse potential. It was hoped that bretazenil and other partial agonists would be an improvement on traditional benzodiazepines which are full agonists due to preclinical evidence that their side effect profile was less than that of full agonist benzodiazepines. For a variety of reasons however, bretazenil and other partial agonists such as pazinaclone and abecarnil were not clinically successful. However, research continues into other compounds with partial agonist and compounds which are selective for certain GABAA benzodiazepine receptor subtypes.

Tolerance and Dependence

In a study in rats, cross-tolerance between the benzodiazepine drug chlordiazepoxide and bretazenil has been demonstrated. In a primate study bretazenil was found to be able to replace the full agonist diazepam in diazepam dependent primates without precipitating withdrawal effects, demonstrating cross tolerance between bretazenil and benzodiazepine agonists, whereas other partial agonists precipitated a withdrawal syndrome. The differences are likely due to differences in intrinsic properties between different benzodiazepine partial agonists. Cross-tolerance has also been shown between bretazenil and full agonist benzodiazepines in rats. In rats tolerance is slower to develop to the anticonvulsant effects compared to the benzodiazepine site full agonist diazepam. However, tolerance developed to the anticonvulsant effects of bretazenil partial agonist more quickly than they developed to imidazenil.

Pharmacology

Bretazenil has a more broad spectrum of action than traditional benzodiazepines as it has been shown to have low affinity binding to α4 and α6 GABAA receptors in addition to acting on α1, α2, α3 and α5 subunits which traditional benzodiazepine drugs work on. The partial agonist imidazenil does not, however, act at these subunits. 0.5mg of bretazenil is approximately equivalent in its psychomotor-impairing effect to 10 mg of diazepam. Bretazenil produces marked sedative-hypnotic effects when taken alone and when combined with alcohol. This human study also indicates that bretazenil is possibly more sedative than diazepam. The reason is unknown, but the study suggests the possibility that a full-agonist metabolite may be generated in humans but not animals previously tested or else that there are significant differences in benzodiazepine receptor population in animals and humans.

In a study of monkeys bretazenil has been found to antagonize the effects of full agonist benzodiazepines. However, bretazenil has been found to enhance the effects of neurosteroids acting on the neurosteroid binding site of the GABAA receptor. Another study found that bretazenil acted as an antagonist provoking withdrawal symptoms in monkeys who were physically dependent on the full agonist benzodiazepine triazolam.

Partial agonists of benzodiazepine receptors have been proposed as a possible alternative to full agonists of the benzodiazepine site to overcome the problems of tolerance, dependence and withdrawal which limits the role of benzodiazepines in the treatment of anxiety, insomnia and epilepsy. Such adverse effects appear to be less problematic with bretazenil than full agonists. Bretazenil has also been found to have less abuse potential than benzodiazepine full agonists such as diazepam and alprazolam, however long-term use of bretazenil would still be expected to result in dependence and addiction.

Bretazenil alters the sleep EEG profile and causes a reduction in cortisol secretion and increases significantly the release of prolactin. Bretazenil has effective hypnotic properties but impairs cognitive ability in humans. Bretazenil causes a reduction in the number of movements between sleep stages and delays movement into REM sleep. At a dosage of 0.5 mg of bretazenil REM sleep is decreased and stage 2 sleep is lengthened.

What is Midazolam?

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Introduction

Midazolam, sold under the brand name Versed, among others, is a benzodiazepine medication used for anaesthesia, procedural sedation, trouble sleeping, and severe agitation.

It works by inducing sleepiness, decreasing anxiety, and causing a loss of ability to create new memories. It is also useful for the treatment of seizures. Midazolam can be given by mouth, intravenously, or injection into a muscle, by spraying into the nose, or through the cheek. When given intravenously, it typically begins working within five minutes; when injected into a muscle, it can take fifteen minutes to begin working. Effects last for between one and six hours.

Side effects can include a decrease in efforts to breathe, low blood pressure, and sleepiness. Tolerance to its effects and withdrawal syndrome may occur following long-term use. Paradoxical effects, such as increased activity, can occur especially in children and older people. There is evidence of risk when used during pregnancy but no evidence of harm with a single dose during breastfeeding. It belongs to the benzodiazepine class of drugs and works by increasing the activity of the GABA neurotransmitter in the brain.

Midazolam was patented in 1974 and came into medical use in 1982. It is on the World Health Organisation’s List of Essential Medicines. Midazolam is available as a generic medication. In many countries, it is a controlled substance.

Brief History

Midazolam is among about 35 benzodiazepines currently used medically, and was synthesized in 1975 by Walser and Fryer at Hoffmann-LaRoche, Inc in the United States. Owing to its water solubility, it was found to be less likely to cause thrombophlebitis than similar drugs. The anticonvulsant properties of midazolam were studied in the late 1970s, but not until the 1990s did it emerge as an effective treatment for convulsive status epilepticus. As of 2010, it is the most commonly used benzodiazepine in anaesthetic medicine. In acute medicine, midazolam has become more popular than other benzodiazepines, such as lorazepam and diazepam, because it is shorter lasting, is more potent, and causes less pain at the injection site. Midazolam is also becoming increasingly popular in veterinary medicine due to its water solubility. In 2018 it was revealed the CIA considered using Midazolam as a “truth serum” on terrorist suspects in project “Medication”.

Medical Uses

Seizures

Midazolam is sometimes used for the acute management of seizures. Long-term use for the management of epilepsy is not recommended due to the significant risk of tolerance (which renders midazolam and other benzodiazepines ineffective) and the significant side effect of sedation. A benefit of midazolam is that in children it can be given in the cheek or in the nose for acute seizures, including status epilepticus. Midazolam is effective for status epilepticus that has not improved following other treatments or when intravenous access cannot be obtained, and has advantages of being water-soluble, having a rapid onset of action and not causing metabolic acidosis from the propylene glycol vehicle (which is not required due to its solubility in water), which occurs with other benzodiazepines.

Drawbacks include a high degree of breakthrough seizures – due to the short half-life of midazolam – in over 50% of people treated, as well as treatment failure in 14-18% of people with refractory status epilepticus. Tolerance develops rapidly to the anticonvulsant effect, and the dose may need to be increased by several times to maintain anticonvulsant therapeutic effects. With prolonged use, tolerance and tachyphylaxis can occur and the elimination half-life may increase, up to days. There is evidence buccal and intranasal midazolam is easier to administer and more effective than rectally administered diazepam in the emergency control of seizures.

Procedural Sedation

Intravenous midazolam is indicated for procedural sedation (often in combination with an opioid, such as fentanyl), for preoperative sedation, for the induction of general anaesthesia, and for sedation of people who are ventilated in critical care units. Midazolam is superior to diazepam in impairing memory of endoscopy procedures, but propofol has a quicker recovery time and a better memory-impairing effect. It is the most popular benzodiazepine in the intensive care unit (ICU) because of its short elimination half-life, combined with its water solubility and its suitability for continuous infusion. However, for long-term sedation, lorazepam is preferred due to its long duration of action, and propofol has advantages over midazolam when used in the ICU for sedation, such as shorter weaning time and earlier tracheal extubation.

Midazolam is sometimes used in neonatal intensive care units. When used, additional caution is required in newborns; midazolam should not be used for longer than 72 hours due to risks of tachyphylaxis, and the possibility of development of a benzodiazepine withdrawal syndrome, as well as neurological complications. Bolus injections should be avoided due to the increased risk of cardiovascular depression, as well as neurological complications. Midazolam is also sometimes used in newborns who are receiving mechanical ventilation, although morphine is preferred, owing to its better safety profile for this indication.

Sedation using midazolam can be used to relieve anxiety and manage behaviour in children undergoing dental treatment.

Agitation

Midazolam, in combination with an antipsychotic drug, is indicated for the acute management of schizophrenia when it is associated with aggressive or out-of-control behaviour.

End of Life Care

In the final stages of end-of-life care, midazolam is routinely used at low doses via subcutaneous injection to help with agitation, myoclonus, restlessness or anxiety in the last hours or days of life. At higher doses during the last weeks of life, midazolam is considered a first line agent in palliative continuous deep sedation therapy when it is necessary to alleviate intolerable suffering not responsive to other treatments, but the need for this is rare.

Contraindications

Benzodiazepines require special precaution if used in the elderly, during pregnancy, in children, in alcohol- or other drug-dependent individuals or those with comorbid psychiatric disorders.[31] Additional caution is required in critically ill patients, as accumulation of midazolam and its active metabolites may occur.[32] Kidney or liver impairments may slow down the elimination of midazolam leading to prolonged and enhanced effects.[33][34] Contraindications include hypersensitivity, acute narrow-angle glaucoma, shock, hypotension, or head injury. Most are relative contraindications.

Side Effects

Refer to Long-term Effects of Benzodiazepine Use.

Side effects of midazolam in the elderly are listed above. People experiencing amnesia as a side effect of midazolam are generally unaware their memory is impaired, unless they had previously known it as a side effect.

Long-term use of benzodiazepines has been associated with long-lasting deficits of memory, and show only partial recovery six months after stopping benzodiazepines. It is unclear whether full recovery occurs after longer periods of abstinence. Benzodiazepines can cause or worsen depression. Paradoxical excitement occasionally occurs with benzodiazepines, including a worsening of seizures. Children and elderly individuals or those with a history of excessive alcohol use and individuals with a history of aggressive behaviour or anger are at increased risk of paradoxical effects. Paradoxical reactions are particularly associated with intravenous administration. After night-time administration of midazolam, residual ‘hangover’ effects, such as sleepiness and impaired psychomotor and cognitive functions, may persist into the next day. This may impair the ability of users to drive safely and may increase the risk of falls and hip fractures. Sedation, respiratory depression and hypotension due to a reduction in systematic vascular resistance, and an increase in heart rate can occur. If intravenous midazolam is given too quickly, hypotension may occur. A “midazolam infusion syndrome” may result from high doses, and is characterised by delayed arousal hours to days after discontinuation of midazolam, and may lead to an increase in the length of ventilatory support needed.

In susceptible individuals, midazolam has been known to cause a paradoxical reaction, a well-documented complication with benzodiazepines. When this occurs, the individual may experience anxiety, involuntary movements, aggressive or violent behaviour, uncontrollable crying or verbalisation, and other similar effects. This seems to be related to the altered state of consciousness or disinhibition produced by the drug. Paradoxical behaviour is often not recalled by the patient due to the amnesia-producing properties of the drug. In extreme situations, flumazenil can be administered to inhibit or reverse the effects of midazolam. Antipsychotic medications, such as haloperidol, have also been used for this purpose.

Midazolam is known to cause respiratory depression. In healthy humans, 0.15 mg/kg of midazolam may cause respiratory depression, which is postulated to be a central nervous system (CNS) effect. When midazolam is administered in combination with fentanyl, the incidence of hypoxemia or apnoea becomes more likely.

Although the incidence of respiratory depression/arrest is low (0.1-0.5%) when midazolam is administered alone at normal doses, the concomitant use with CNS acting drugs, mainly analgesic opiates, may increase the possibility of hypotension, respiratory depression, respiratory arrest, and death, even at therapeutic doses. Potential drug interactions involving at least one CNS depressant were observed for 84% of midazolam users who were subsequently required to receive the benzodiazepine antagonist flumazenil. Therefore, efforts directed toward monitoring drug interactions and preventing injuries from midazolam administration are expected to have a substantial impact on the safe use of this drug

Pregnancy and Breastfeeding

Midazolam, when taken during the third trimester of pregnancy, may cause risk to the neonate, including benzodiazepine withdrawal syndrome, with possible symptoms including hypotonia, apnoeic spells, cyanosis, and impaired metabolic responses to cold stress. Symptoms of hypotonia and the neonatal benzodiazepine withdrawal syndrome have been reported to persist from hours to months after birth. Other neonatal withdrawal symptoms include hyperexcitability, tremor, and gastrointestinal upset (diarrhoea or vomiting). Breastfeeding by mothers using midazolam is not recommended.

Elderly

Additional caution is required in the elderly, as they are more sensitive to the pharmacological effects of benzodiazepines, metabolise them more slowly, and are more prone to adverse effects, including drowsiness, amnesia (especially anterograde amnesia), ataxia, hangover effects, confusion, and falls.

Tolerance, Dependence, and Withdrawal

A benzodiazepine dependence occurs in about one-third of individuals who are treated with benzodiazepines for longer than 4 weeks, which typically results in tolerance and benzodiazepine withdrawal syndrome when the dose is reduced too rapidly. Midazolam infusions may induce tolerance and a withdrawal syndrome in a matter of days. The risk factors for dependence include dependent personality, use of a benzodiazepine that is short-acting, high potency and long-term use of benzodiazepines. Withdrawal symptoms from midazolam can range from insomnia and anxiety to seizures and psychosis. Withdrawal symptoms can sometimes resemble a person’s underlying condition. Gradual reduction of midazolam after regular use can minimise withdrawal and rebound effects. Tolerance and the resultant withdrawal syndrome may be due to receptor down-regulation and GABAA receptor alterations in gene expression, which causes long-term changes in the function of the GABAergic neuronal system.

Chronic users of benzodiazepine medication who are given midazolam experience reduced therapeutic effects of midazolam, due to tolerance to benzodiazepines. Prolonged infusions with midazolam results in the development of tolerance; if midazolam is given for a few days or more a withdrawal syndrome can occur. Therefore, preventing a withdrawal syndrome requires that a prolonged infusion be gradually withdrawn, and sometimes, continued tapering of dose with an oral long-acting benzodiazepine such as clorazepate dipotassium. When signs of tolerance to midazolam occur during intensive care unit sedation the addition of an opioid or propofol is recommended. Withdrawal symptoms can include irritability, abnormal reflexes, tremors, clonus, hypertonicity, delirium and seizures, nausea, vomiting, diarrhoea, tachycardia, hypertension, and tachypnoea. In those with significant dependence, sudden discontinuation may result in withdrawal symptoms such as status epilepticus that may be fatal.

Overdose

Refer to Benzodiazepine Overdose.

A midazolam overdose is considered a medical emergency and generally requires the immediate attention of medical personnel. Benzodiazepine overdose in healthy individuals is rarely life-threatening with proper medical support; however, the toxicity of benzodiazepines increases when they are combined with other CNS depressants such as alcohol, opioids, or tricyclic antidepressants. The toxicity of benzodiazepine overdose and risk of death is also increased in the elderly and those with obstructive pulmonary disease or when used intravenously. Treatment is supportive; activated charcoal can be used within an hour of the overdose. The antidote for an overdose of midazolam (or any other benzodiazepine) is flumazenil. While effective in reversing the effects of benzodiazepines it is not used in most cases as it may trigger seizures in mixed overdoses and benzodiazepine dependent individuals.

Symptoms of midazolam overdose can include:

  • Ataxia.
  • Dysarthria.
  • Nystagmus.
  • Slurred speech.
  • Somnolence (difficulty staying awake).
  • Mental confusion.
  • Hypotension.
  • Respiratory arrest.
  • Vasomotor collapse.
  • Impaired motor functions.
    • Impaired reflexes.
    • Impaired coordination.
    • Impaired balance.
  • Dizziness.
  • Coma.
  • Death.

Detection in Body Fluids

Concentrations of midazolam or its major metabolite, 1-hydroxymidazolam glucuronide, may be measured in plasma, serum, or whole blood to monitor for safety in those receiving the drug therapeutically, to confirm a diagnosis of poisoning in hospitalised patients, or to assist in a forensic investigation of a case of fatal overdosage. Patients with renal dysfunction may exhibit prolongation of elimination half-life for both the parent drug and its active metabolite, with accumulation of these two substances in the bloodstream and the appearance of adverse depressant effects.

Interactions

Protease inhibitors, nefazodone, sertraline, grapefruit, fluoxetine, erythromycin, diltiazem, clarithromycin inhibit the metabolism of midazolam, leading to a prolonged action. St John’s wort, rifapentine, rifampin, rifabutin, phenytoin enhance the metabolism of midazolam leading to a reduced action. Sedating antidepressants, antiepileptic drugs such as phenobarbital, phenytoin and carbamazepine, sedative antihistamines, opioids, antipsychotics and alcohol enhance the sedative effects of midazolam. Midazolam is metabolised almost completely by cytochrome P450-3A4. Atorvastatin administration along with midazolam results in a reduced elimination rate of midazolam. St John’s wort decreases the blood levels of midazolam. Grapefruit juice reduces intestinal 3A4 and results in less metabolism and higher plasma concentrations.

Pharmacology

Midazolam is a short-acting benzodiazepine in adults with an elimination half-life of 1.5-2.5 hours. In the elderly, as well as young children and adolescents, the elimination half-life is longer. Midazolam is metabolised into an active metabolite alpha1-hydroxymidazolam. Age-related deficits, renal and liver status affect the pharmacokinetic factors of midazolam as well as its active metabolite. However, the active metabolite of midazolam is minor and contributes to only 10% of biological activity of midazolam. Midazolam is poorly absorbed orally, with only 50% of the drug reaching the bloodstream. Midazolam is metabolised by cytochrome P450 (CYP) enzymes and by glucuronide conjugation. The therapeutic as well as adverse effects of midazolam are due to its effects on the GABAA receptors; midazolam does not activate GABAA receptors directly but, as with other benzodiazepines, it enhances the effect of the neurotransmitter GABA on the GABAA receptors (↑ frequency of Cl− channel opening) resulting in neural inhibition. Almost all of the properties can be explained by the actions of benzodiazepines on GABAA receptors. This results in the following pharmacological properties being produced: sedation, induction of sleep, reduction in anxiety, anterograde amnesia, muscle relaxation and anticonvulsant effects.

Society and Culture

Cost

Midazolam is available as a generic medication.

Availability

Midazolam is available in the United States as a syrup or as an injectable solution.

Dormicum brand midazolam is marketed by Roche as white, oval, 7.5-mg tablets in boxes of two or three blister strips of 10 tablets, and as blue, oval, 15-mg tablets in boxes of two (Dormonid 3x) blister strips of 10 tablets. The tablets are imprinted with “Roche” on one side and the dose of the tablet on the other side. Dormicum is also available as 1-, 3-, and 10-ml ampoules at a concentration of 5 mg/ml. Another manufacturer, Novell Pharmaceutical Laboratories, makes it available as Miloz in 3- and 5-ml ampoules. Midazolam is the only water-soluble benzodiazepine available. Another maker is Roxane Laboratories; the product in an oral solution, Midazolam HCl Syrup, 2 mg/ml clear, in a red to purplish-red syrup, cherry in flavour. It becomes soluble when the injectable solution is buffered to a pH of 2.9-3.7. Midazolam is also available in liquid form. It can be administered intramuscularly, intravenously, intrathecally, intranasally, buccally, or orally.

Legal Status

In the Netherlands, midazolam is a List II drug of the Opium Law. Midazolam is a Schedule IV drug under the Convention on Psychotropic Substances. In the United Kingdom, midazolam is a Schedule 3/Class C controlled drug. In the United States, midazolam (DEA number 2884) is on the Schedule IV list of the Controlled Substances Act as a non-narcotic agent with low potential for abuse.

Marketing Authorisation

In 2011, the European Medicines Agency (EMA) granted a marketing authorisation for a buccal application form of midazolam, sold under the trade name Buccolam. Buccolam was approved for the treatment of prolonged, acute, convulsive seizures in people from three months to less than 18 years of age. This was the first application of a paediatric-use marketing authorisation.

Use in Executions

The drug has been introduced for use in executions by lethal injection in certain jurisdictions in the United States in combination with other drugs. It was introduced to replace pentobarbital after the latter’s manufacturer disallowed that drug’s use for executions. Midazolam acts as a sedative to render the condemned prisoner unconscious, at which time vecuronium bromide and potassium chloride are administered, stopping the prisoner’s breathing and heart, respectively.

Midazolam has been used as part of a three-drug cocktail, with vecuronium bromide and potassium chloride in Florida and Oklahoma prisons. Midazolam has also been used along with hydromorphone in a two-drug protocol in Ohio and Arizona.

The usage of midazolam in executions became controversial after condemned inmate Clayton Lockett apparently regained consciousness and started speaking midway through his 2014 execution when the state of Oklahoma attempted to execute him with an untested three-drug lethal injection combination using 100 mg of midazolam. Prison officials reportedly discussed taking him to a hospital before he was pronounced dead of a heart attack 40 minutes after the execution began. An observing doctor stated that Lockett’s vein had ruptured. It is not clear which drug or drugs caused his death or what quantities of vecuronium bromide and potassium chloride were released before the execution was cancelled.

Notable Incidents

The state of Florida used midazolam to execute William Frederick Happ in October 2013.

The state of Ohio used midazolam in the execution of Dennis McGuire in January 2014; it took McGuire 24 minutes to die after the procedure started, and he gasped and appeared to be choking during that time, leading to questions about the dosing and timing of the drug administration, as well as the choice of drugs.

The execution of Ronald Bert Smith in the state of Alabama on 08 December 2016, “went awry soon after (midazolam) was administered” again putting the effectiveness of the drug in question.

In October 2016, the state of Ohio announced that it would resume executions in January 2017, using a formulation of midazolam, vecuronium bromide, potassium chloride, but this was blocked by a Federal judge. On 26 July 2017, Ronald Phillips was executed with a three-drug cocktail including midazolam after the Supreme Court refused to grant a stay.[86] Prior to this, the last execution in Ohio had been that of Dennis McGuire. Murderer Gary Otte’s lawyers unsuccessfully challenged his Ohio execution, arguing that midazolam might not protect him from serious pain when the other drugs are administered. He died without incident in about 14 minutes on 13 September 2017.

On 24 April 2017, the state of Arkansas carried out a double-execution of Jack Harold Jones, 52, and Marcel Williams, 46. The state of Arkansas attempted to execute eight people before its supply of midazolam expired on 30 April 2017. Two of them were granted a stay of execution, and another, Ledell T. Lee, 51, was executed on 20 April 2017.

Legal Challenges

In Glossip v. Gross, attorneys for three Oklahoma inmates argued that midazolam could not achieve the level of unconsciousness required for surgery, meaning severe pain and suffering was likely. They argued that midazolam was cruel and unusual punishment and thus contrary to the Eighth Amendment to the United States Constitution. In June 2015, the US Supreme Court ruled that they had failed to prove that midazolam was cruel and unusual when compared to known, available alternatives.

The state of Nevada is also known to use midazolam in execution procedures. In July 2018, one of the manufacturers accused state officials of obtaining the medication under false pretences. This incident was the first time a drug company successfully, though temporarily, halted an execution. A previous attempt in 2017, to halt an execution in the state of Arizona by another drug manufacturer was not successful.

What is Imidazenil?

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Introduction

Imidazenil is an experimental anxiolytic drug which is derived from the benzodiazepine family, and is most closely related to other imidazobenzodiazepines such as midazolam, flumazenil, and bretazenil.

Outline

Imidazenil is a highly potent benzodiazepine receptor partial agonist with an unusual profile of effects, producing some of the effects associated with normal benzodiazepines such as anticonvulsant and anxiolytic effects, yet without any notable sedative or amnestic effects. In fact, imidazenil blocks the sedative effects of diazepam, yet without lowering the convulsion threshold, and so potentially could be a more flexible antidote than the antagonist flumazenil which is commonly used to treat benzodiazepine overdose at present.

As of August 2021, Imidazenil has not yet been developed commercially for use in humans, however it has been suggested as a safe and effective treatment for anxiety, a potent yet non-sedating anticonvulsant which might be particularly useful in the treatment of poisoning with organophosphate nerve agents, and as a novel treatment for schizophrenia.

What is Flumazenil?

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Introduction

Flumazenil (also known as flumazepil, code name Ro 15-1788) is a selective GABAA receptor antagonist administered via injection, otic insertion, or intranasally. Therapeutically, it acts as both an antagonist and antidote to benzodiazepines (particularly in cases of overdose), through competitive inhibition.

It was first characterised in 1981, and was first marketed in 1987 by Hoffmann-La Roche under the trade name Anexate. However, it did not receive US Food and Drug Administration (FDA) approval until 20 December 1991. The developer lost its exclusive patent rights in 2008; so at present, generic formulations of this drug are available. Intravenous flumazenil is primarily used to treat benzodiazepine overdoses and to help reverse anaesthesia. Administration of flumazenil by sublingual lozenge and topical cream has also been tested.

Medical Uses

Flumazenil benefits patients who become excessively drowsy after use of benzodiazepines for either diagnostic or therapeutic procedures.

The drug has been used as an antidote in the treatment of benzodiazepine overdoses. It reverses the effects of benzodiazepines by competitive inhibition at the benzodiazepine (BZ) recognition site on the GABA/benzodiazepine receptor complex. There are many complications that must be taken into consideration when used in the acute care setting. These include lowered seizure threshold, agitation, and anxiousness. Flumazenil’s short half-life requires multiple doses. Because of the potential risks of withdrawal symptoms and the drug’s short half-life, patients must be carefully monitored to prevent recurrence of overdose symptoms or adverse side effects.

Flumazenil is also sometimes used after surgery to reverse the sedative effects of benzodiazepines. This is similar to naloxone’s application to reverse the effect of opiates and opioids following surgery. Administration of the drug requires careful monitoring by an anaesthesiologist due to potential side effects and serious risks associated with over-administration. Likewise, post-surgical monitoring is also necessary because flumazenil can mask the apparent metabolisation (“wearing off”) of the drug after removal of patient life-support and monitoring equipment.

Flumazenil has been effectively used to treat overdoses of non-benzodiazepine hypnotics, such as zolpidem, zaleplon and zopiclone (also known as “Z-drugs”).

It may also be effective in reducing excessive daytime sleepiness while improving vigilance in primary hypersomnias, such as idiopathic hypersomnia.

The drug has also been used in hepatic encephalopathy. It may have beneficial short‐term effects in people with cirrhosis, but there is no evidence for long-term benefits.

The onset of action is rapid, and effects are usually seen within one to two minutes. The peak effect is seen at six to ten minutes. The recommended dose for adults is 200 μg every 1-2 minutes until the effect is seen, up to a maximum of 3 mg per hour. It is available as a clear, colourless solution for intravenous injection, containing 500 μg in 5 mL.

Many benzodiazepines (including midazolam) have longer half-lives than flumazenil. Therefore, in cases of overdose, repeat doses of flumazenil may be required to prevent recurrent symptoms once the initial dose of flumazenil wears off.

It is hepatically metabolised to inactive compounds which are excreted in the urine. Individuals who are physically dependent on benzodiazepines may suffer benzodiazepine withdrawal symptoms, including seizure, upon rapid administration of flumazenil.

It is not recommended for routine use in those with a decreased level of consciousness.

In terms of drug enforcement initiatives, diversion control programs and required post-marketing surveillance of adverse events, orders for flumazenil may trigger a prescription audit to the search for benzodiazepine misuse and for clinically significant adverse reactions related to their use.

PET Radioligand

Radiolabeled with the radioactive isotope carbon-11, flumazenil may be used as a radioligand in neuroimaging with positron emission tomography to visualize the distribution of GABAA receptors in the human brain.

Treatment for Benzodiazepine Dependence & Tolerance

Epileptic patients who have become tolerant to the anti-seizure effects of the benzodiazepine clonazepam became seizure-free for several days after treatment with 1.5 mg of flumazenil. Similarly, patients who were dependent on high doses of benzodiazepines (median dosage 333 mg diazepam-equivalent) were able to be stabilised on a low dose of clonazepam after 7-8 days of treatment with flumazenil.

Flumazenil has been tested against placebo in benzo-dependent subjects. Results showed that typical benzodiazepine withdrawal effects were reversed with few to no symptoms. Flumazenil was also shown to produce significantly fewer withdrawal symptoms than saline in a randomised, placebo-controlled study with benzodiazepine-dependent subjects. Additionally, relapse rates were much lower during subsequent follow-up.

In vitro studies of tissue cultured cell lines have shown that chronic treatment with flumazenil enhanced the benzodiazepine binding site where such receptors have become more numerous and uncoupling/down-regulation of GABAA has been reversed. After long-term exposure to benzodiazepines, GABAA receptors become down-regulated and uncoupled. Growth of new receptors and recoupling after prolonged flumazenil exposure has also been observed. It is thought this may be due to increased synthesis of receptor proteins.[20]

Flumazenil was found to be more effective than placebo in reducing feelings of hostility and aggression in patients who had been free of benzodiazepines for 4–266 weeks. This may suggest a role for flumazenil in treating protracted benzodiazepine withdrawal symptoms.

Low-dose, slow subcutaneous flumazenil administration is a safe procedure for patients withdrawing from long-term, high-dose benzodiazepine dependency. It has a low risk of seizures even amongst those who have experienced convulsions when previously attempting benzodiazepine withdrawal.

In Italy, the gold standard for treatment of high-dose benzodiazepine dependency is 8-10 days of low-dose, slowly infused flumazenil. One addiction treatment centre in Italy has used flumazenil to treat over 300 patients who were dependent on high doses of benzodiazepines (up to 70 times higher than conventionally prescribed) with physicians being among the clinic’s most common patients.

Clinical Pharmacology

Flumazenil, an imidazobenzodiazepine derivative, antagonizes the actions of benzodiazepines on the central nervous system. Flumazenil competitively inhibits the activity at the benzodiazepine recognition site on the GABA/benzodiazepine receptor complex. It also exhibits weak partial agonism of GABAA receptor complexes that contain α6-type monomers; the clinical relevance of this is unknown.

Flumazenil does not antagonize all of the central nervous system effects of drugs affecting GABA-ergic neurons by means other than the benzodiazepine receptor (including ethanol, barbiturates, and most anaesthetics) and does not reverse the effects of opioids. It will however antagonize the action of non-benzodiazepine z-drugs, such as zolpidem and zopiclone, because they act via the benzodiazepine site of the GABA receptor – it has been used to successfully treat z-drug overdose.

Pharmacodynamics

Intravenous flumazenil has been shown to antagonize sedation, impairment of recall, psychomotor impairment and ventilatory depression produced by benzodiazepines in healthy human volunteers.

The duration and degree of reversal of sedative benzodiazepine effects are related to the dose and plasma concentrations of flumazenil.

Availability

Flumazenil is sold under a wide variety of brand names worldwide like Anexate, Lanexat, Mazicon, Romazicon. In India it is manufactured by Roche Bangladesh Pharmaceuticals and USAN Pharmaceuticals.

What is Benzodiazepine Withdrawal Syndrome?

Published on by Andrew Marshall26 Comments

Introduction

Benzodiazepine withdrawal syndrome – often abbreviated to benzo withdrawal or BZD withdrawal – is the cluster of signs and symptoms that emerge when a person who has been taking benzodiazepines, either medically or recreationally, and has developed a physical dependence, undergoes dosage reduction or discontinuation.

Refer to Benzodiazepine Use Disorder, Benzodiazepine Dependence, Benzodiazepine Overdose, and Long-Term Effects of Benzodiazepine Use.

Development of physical dependence and the resulting withdrawal symptoms, some of which may last for years, may result from taking the medication as prescribed. Benzodiazepine withdrawal is characterized by sleep disturbance, irritability, increased tension and anxiety, panic attacks, hand tremor, shaking, sweating, difficulty with concentration, confusion and cognitive difficulty, memory problems, dry retching and nausea, weight loss, palpitations, headache, muscular pain and stiffness, a host of perceptual changes, hallucinations, seizures, psychosis, and increased risk of suicide. Further, these symptoms are notable for the manner in which they wax and wane and vary in severity from day to day or week by week instead of steadily decreasing in a straightforward monotonic manner. This phenomenon is often referred to as “waves” and “windows”.

It is a potentially serious condition, and is complex and often protracted in its course. Long-term benzodiazepine use, defined as daily use for at least three months, is not desirable because of the associated increased risk of dependence, dose escalation, loss of efficacy, increased risk of accidents and falls, particularly for the elderly, as well as cognitive, neurological, and intellectual impairments. Use of short-acting hypnotics, while being effective at initiating sleep, worsens the second half of sleep due to withdrawal effects.

Benzodiazepine withdrawal can be severe and can provoke life-threatening withdrawal symptoms, such as seizures, particularly with abrupt or overly rapid dosage reduction from high doses or long-time use. A severe withdrawal response can nevertheless occur despite gradual dose reduction, or from relatively low doses in short-time users; even after a single large dose in animal models. A minority of individuals will experience a protracted withdrawal syndrome, whose symptoms may persist at a sub-acute level for months or years after cessation of benzodiazepines. The likelihood of developing a protracted withdrawal syndrome can be minimised by a slow, gradual reduction in dosage.

Chronic exposure to benzodiazepines causes neural adaptations that counteract the drug’s effects, leading to tolerance and dependence. Despite taking a constant therapeutic dose, long-term use of benzodiazepines may lead to the emergence of withdrawal-like symptoms, particularly between doses, when patients are treated with shorter-acting benzodiazepines. When the drug is discontinued or the dosage reduced, withdrawal symptoms may appear and remain until the body has reversed the long-term physiological adaptations. These rebound symptoms may be identical to the symptoms for which the drug was initially taken, or may be part of discontinuation symptoms. In severe cases, the withdrawal reaction may exacerbate or resemble serious psychiatric and medical conditions, such as mania, schizophrenia, and, especially at high doses, seizure disorders. Failure to recognise discontinuation symptoms can lead to false evidence for the need to take benzodiazepines, which in turn leads to withdrawal failure and reinstatement of benzodiazepines, often at higher doses.

Awareness of the withdrawal reactions, individualised taper strategies according to withdrawal severity, the addition of alternative strategies such as reassurance and referral to benzodiazepine withdrawal support groups, all increase the success rate of withdrawal.

Signs and Symptoms

Withdrawal effects caused by sedative-hypnotics discontinuation, such as benzodiazepines, barbiturates, or alcohol, can cause serious medical complications. They are cited to be more hazardous to withdraw from than opioids. Users typically receive little advice and support for discontinuation. Some withdrawal symptoms are identical to the symptoms for which the medication was originally prescribed, and can be acute or protracted in duration. Onset of symptoms from long half-life benzodiazepines might be delayed for up to three weeks, although withdrawal symptoms from short-acting ones often present early, usually within 24-48 hours. There may be no fundamental differences in symptoms from either high or low dose discontinuation, but symptoms tend to be more severe from higher doses.

Daytime re-emergence and rebound withdrawal symptoms, sometimes confused with interdose withdrawal, may occur once dependence has set in. ‘Re-emergence’ is the return of symptoms for which the drug was initially prescribed, in contrast, ‘rebound’ symptoms are a return of the symptoms for which the benzodiazepine was initially taken, but at a more intense level than before; whereas ‘interdose withdrawal’ is when a prior dosage of drug wears off and beginnings of an entirely new cycle of withdrawal sets in, the symptoms of which dissipate upon taking the next dosage but after which yet another entirely new cycle of withdrawal begins when that dosage wears off, a new onset of withdrawal between each dosage thus called ‘interdose withdrawal’ and if not properly treated can recur indefinitely in a vicious circle (for which a benzo with a long half life, e.g. diazepam, can be substituted so the drug does not wear off between doses).

Withdrawal symptoms may appear for the first time during dose reduction, and include insomnia, anxiety, distress, weight loss, dizziness, night sweats, shakes, muscle twitches, aphasia, panic attacks, depression, derealization, paranoia, indigestion, diarrhoea, photo phobia etc., and are more commonly associated with short-acting benzodiazepines discontinuation, like triazolam. Daytime symptoms can occur after a few days to a few weeks of administration of nightly benzodiazepines or z-drugs such as zopiclone; withdrawal-related insomnia rebounds worse than baseline, and for rapidly eliminated benzodiazepines, including triazolam and temazepam, this may occur even when used briefly and intermittently, according to a small 1991 study (n=18).

The following symptoms may emerge during gradual or abrupt dosage reduction:

  • Akathisia.
  • Agitation and anxiety, possible terror and panic attacks.
  • Blurred vision.
  • Chest pain.
  • Depersonalisation and derealisation (feelings of unreality).
  • Depression (can be severe), possible suicidal ideation.
  • Dilated pupils.
  • Dizziness.
  • Dry mouth.
  • Dysphoria.
  • Elevation in blood pressure.
  • Fatigue and weakness.
  • Gastrointestinal disturbance (including nausea, diarrhoea, vomiting).
  • Hearing disturbance.
  • Headache.
  • Hot and cold spells.
  • Hyperosmia.
  • Hyperacusis.
  • Hypertension.
  • Hypnagogic hallucinations.
  • Hypochondriasis.
  • Increased sensitivity to touch.
  • Increased urinary frequency.
  • Insomnia.
  • Impaired memory and concentration.
  • Loss of appetite and weight loss.
  • Mild to moderate aphasia.
  • Mood swings.
  • Muscular spasms, cramps, discomfort or fasciculations.
  • Nightmares.
  • Obsessive compulsive disorder (OCD).
  • Paraesthesia.
  • Paranoia.
  • Perspiration.
  • Photophobia.
  • Postural hypotension.
  • REM sleep rebound.
  • Restless legs syndrome.
  • Stiffness.
  • Taste and smell disturbances.
  • Tachycardia.
  • Tinnitus.
  • Tremor.
  • Visual disturbances.

Rapid discontinuation may result in a more serious syndrome.

  • Catatonia, which may result in death.
  • Confusion.
  • Convulsions, which may result in death.
  • Coma.
  • Delirium tremens.
  • Hyperthermia.
  • Mania.
  • Neuroleptic malignant syndrome-like event.
  • Organic brain syndrome.
  • Post-traumatic stress disorder (PTSD).
  • Psychosis.
  • Suicidal ideation or suicide.
  • Violence and aggression.

As withdrawal progresses, patients often find their physical and mental health improves with improved mood and improved cognition.

Mechanism

Refer to Benzodiazepine Dependence.

The neuroadaptive processes involved in tolerance, dependence, and withdrawal mechanisms implicate both the GABAergic and the glutamatergic systems. Gamma-Aminobutyric acid (GABA) is the major inhibitory neurotransmitter of the central nervous system; roughly one-quarter to one-third of synapses use GABA. GABA mediates the influx of chloride ions through ligand-gated chloride channels called GABAA receptors. When chloride enters the nerve cell, the cell membrane potential hyperpolarizes thereby inhibiting depolarisation, or reduction in the firing rate of the post-synaptic nerve cell. Benzodiazepines potentiate the action of GABA, by binding a site between the α and γ subunits of the 5-subunit receptor thereby increasing the frequency of the GABA-gated chloride channel opening in the presence of GABA.

When potentiation is sustained by long-term use, neuroadaptations occur which result in decreased GABAergic response. What is certain is that surface GABAA receptor protein levels are altered in response to benzodiazepine exposure, as is receptor turnover rate. The exact reason for the reduced responsiveness has not been elucidated but down-regulation of the number of receptors has only been observed at some receptor locations including in the pars reticulata of the substantia nigra; down-regulation of the number of receptors or internalization does not appear to be the main mechanism at other locations. Evidence exists for other hypotheses including changes in the receptor conformation, changes in turnover, recycling, or production rates, degree of phosphorylation and receptor gene expression, subunit composition, decreased coupling mechanisms between the GABA and benzodiazepine site, decrease in GABA production, and compensatory increased glutamatergic activity. A unified model hypothesis involves a combination of internalization of the receptor, followed by preferential degradation of certain receptor sub-units, which provides the nuclear activation for changes in receptor gene transcription.

It has been postulated that when benzodiazepines are cleared from the brain, these neuroadaptations are “unmasked”, leading to unopposed excitability of the neuron. Glutamate is the most abundant excitatory neurotransmitter in the vertebrate nervous system. Increased glutamate excitatory activity during withdrawal may lead to sensitisation or kindling of the CNS, possibly leading to worsening cognition and symptomatology and making each subsequent withdrawal period worse. Those who have a prior history of withdrawing from benzodiazepines are found to be less likely to succeed the next time around.

Diagnosis

In severe cases, the withdrawal reaction or protracted withdrawal may exacerbate or resemble serious psychiatric and medical conditions, such as mania, schizophrenia, agitated depression, panic disorder, generalised anxiety disorder, and complex partial seizures and, especially at high doses, seizure disorders. Failure to recognise discontinuation symptoms can lead to false evidence for the need to take benzodiazepines, which in turn leads to withdrawal failure and reinstatement of benzodiazepines, often to higher doses. Pre-existing disorder or other causes typically do not improve, whereas symptoms of protracted withdrawal gradually improve over the ensuing months.

Symptoms may lack a psychological cause and can fluctuate in intensity with periods of good and bad days until eventual recovery.

Prevention

According to the British National Formulary, it is better to withdraw too slowly rather than too quickly from benzodiazepines. The rate of dosage reduction is best carried out so as to minimise the symptoms’ intensity and severity. Anecdotally, a slow rate of reduction may reduce the risk of developing a severe protracted syndrome.

Long half-life benzodiazepines like diazepam or chlordiazepoxide are preferred to minimize rebound effects and are available in low dose forms. Some people may not fully stabilise between dose reductions, even when the rate of reduction is slowed. Such people sometimes simply need to persist as they may not feel better until they have been fully withdrawn from them for a period of time.

Management

Management of benzodiazepine dependence involves considering the person’s age, comorbidity and the pharmacological pathways of benzodiazepines. Psychological interventions may provide a small but significant additional benefit over gradual dose reduction alone at post-cessation and at follow-up. The psychological interventions studied were relaxation training, cognitive-behavioural treatment of insomnia, and self-monitoring of consumption and symptoms, goal-setting, management of withdrawal and coping with anxiety.

There is no standard approach to managing benzodiazepine withdrawal. With sufficient motivation and the proper approach, almost anyone can successfully withdraw from benzodiazepines. However, a prolonged and severe withdrawal syndrome can cause profound disability, which may lead to breakdown of relationships, loss of employment, financial difficulties, as well as more serious adverse effects such as hospitalisation and suicide. As such, long-term users should not be forced to discontinue against their will.

Over-rapid withdrawal, lack of explanation, and failure to reassure individuals that they are experiencing temporary withdrawal symptoms led some people to experience increased panic and fears they are going mad, with some people developing a condition similar to post-traumatic stress disorder as a result. A slow withdrawal regimen, coupled with reassurance from family, friends, and peers improves the outcome. According to a 2015 Cochrane review, cognitive behaviour therapy (CBT) plus taper was effective in achieving discontinuation in the short-term but the effect was not certain after six months.

Medications

While some substitutive pharmacotherapies may have promise, current evidence is insufficient to support their use. Some studies found that the abrupt substitution of substitutive pharmacotherapy was actually less effective than gradual dose reduction alone, and only three studies found benefits of adding melatonin, paroxetine, trazodone, or valproate in conjunction with a gradual dose reduction.

  • Antipsychotics are generally ineffective for benzodiazepine withdrawal-related psychosis.
    • Antipsychotics should be avoided during benzodiazepine withdrawal as they tend to aggravate withdrawal symptoms, including convulsions.
    • Some antipsychotic agents may be riskier than others during withdrawal, especially clozapine, olanzapine or low potency phenothiazines (e.g. chlorpromazine), as they lower the seizure threshold and can worsen withdrawal effects; if used, extreme caution is required.
  • Barbiturates are cross tolerant to benzodiazepines and should generally be avoided; however phenobarbital can be used, as it is relatively safe, see below.
  • Benzodiazepines or cross tolerant drugs should be avoided after discontinuation, even occasionally.
    • These include the nonbenzodiazepines Z-drugs, which have a similar mechanism of action.
    • This is because tolerance to benzodiazepines has been demonstrated to be still present at four months to two years after withdrawal depending on personal biochemistry.
    • Re-exposures to benzodiazepines typically resulted in a reactivation of the tolerance and benzodiazepine withdrawal syndrome.
  • Bupropion, which is used primarily as an antidepressant and smoking cessation aid, is contraindicated in persons experiencing abrupt withdrawal from benzodiazepines or other sedative-hypnotics (e.g. alcohol), due to an increased risk of seizures.
  • Buspirone augmentation was not found to increase the discontinuation success rate.
  • Caffeine may worsen withdrawal symptoms because of its stimulatory properties.
    • At least one animal study has shown some modulation of the benzodiazepine site by caffeine, which produces a lowering of seizure threshold.
  • Carbamazepine, an anticonvulsant, appears to have some beneficial effects in the treatment and management of benzodiazepine withdrawal; however, research is limited and thus the ability of experts to make recommendations on its use for benzodiazepine withdrawal is not possible at present.
  • Ethanol, the primary alcohol in alcoholic beverages, even mild to moderate use, has been found to be a significant predictor of withdrawal failure, probably because of its cross tolerance with benzodiazepines.
  • Flumazenil has been found to stimulate the reversal of tolerance and the normalisation of receptor function. However, further research is needed in the form of randomised trials to demonstrate its role in the treatment of benzodiazepine withdrawal.
    • Flumazenil stimulates the up-regulation and reverses the uncoupling of benzodiazepine receptors to the GABAA receptor, thereby reversing tolerance and reducing withdrawal symptoms and relapse rates.
    • Because of limited research and experience compared to the possible risks involved, the flumazenil detoxification method is controversial and can only be done as an inpatient procedure under medical supervision.
    • Flumazenil was found to be more effective than placebo in reducing feelings of hostility and aggression in patients who had been free of benzodiazepines for 4-266 weeks.
    • This may suggest a role for flumazenil in treating protracted benzodiazepine withdrawal symptoms.
    • A study into the effects of the benzodiazepine receptor antagonist, flumazenil, on benzodiazepine withdrawal symptoms persisting after withdrawal was carried out by Lader and Morton.
    • Study subjects had been benzodiazepine-free for between one month and five years, but all reported persisting withdrawal effects to varying degrees.
    • Persistent symptoms included clouded thinking, tiredness, muscular symptoms such as neck tension, depersonalisation, cramps and shaking and the characteristic perceptual symptoms of benzodiazepine withdrawal, namely, pins and needles feeling, burning skin, pain and subjective sensations of bodily distortion.
    • Therapy with 0.2-2 mg of flumazenil intravenously was found to decrease these symptoms in a placebo-controlled study.
    • This is of interest as benzodiazepine receptor antagonists are neutral and have no clinical effects.
    • The author of the study suggested the most likely explanation is past benzodiazepine use and subsequent tolerance had locked the conformation of the GABA-BZD receptor complex into an inverse agonist conformation, and the antagonist flumazenil resets benzodiazepine receptors to their original sensitivity.
    • Flumazenil was found in this study to be a successful treatment for protracted benzodiazepine withdrawal syndrome, but further research is required.
    • A study by Professor Borg in Sweden produced similar results in patients suffering from protracted withdrawal.
    • In 2007, Hoffmann-La Roche the makers of flumazenil, acknowledged the existence of protracted benzodiazepine withdrawal syndromes, but did not recommended flumazenil to treat the condition.
  • Fluoroquinolone antibiotics have been noted to increase the incidence of a CNS toxicity from 1% in the general population, to 4% in benzodiazepine-dependent population or in those undergoing withdrawal from them.
    • This is probably the result of their GABA antagonistic effects as they have been found to competitively displace benzodiazepines from benzodiazepine receptor sites.
    • This antagonism can precipitate acute withdrawal symptoms, that can persist for weeks or months before subsiding.
    • The symptoms include depression, anxiety, psychosis, paranoia, severe insomnia, paraesthesia, tinnitus, hypersensitivity to light and sound, tremors, status epilepticus, suicidal thoughts and suicide attempt.
    • Fluoroquinolone antibiotics should be contraindicated in patients who are dependent on or in benzodiazepine withdrawal.
    • NSAIDs have some mild GABA antagonistic properties and animal research indicate that some may even displace benzodiazepines from their binding site.
    • However, NSAIDs taken in combination with fluoroquinolones cause a very significant increase in GABA antagonism, GABA toxicity, seizures, and other severe adverse effects.
  • Imidazenil has received some research for management of benzodiazepine withdrawal, but is not currently used in withdrawal.
  • Imipramine was found to statistically increase the discontinuation success rate.
  • Melatonin augmentation was found to statistically increase the discontinuation success rate for people with insomnia.
  • Phenobarbital, (a barbiturate), is used at “detox” or other inpatient facilities to prevent seizures during rapid withdrawal or cold turkey.
    • The phenobarbital is followed by a one- to two-week taper, although a slow taper from phenobarbital is preferred.
    • In a comparison study, a rapid taper using benzodiazepines was found to be superior to a phenobarbital rapid taper.
  • Pregabalin may help reduce the severity of benzodiazepine withdrawal symptoms, and reduce the risk of relapse.
  • Propranolol was not found to increase the discontinuation success rate.
  • SSRI antidepressants have been found to have little value in the treatment of benzodiazepine withdrawal.
  • Trazodone was not found to increase the discontinuation success rate.

Inpatient Treatment

Inpatient drug detox or rehabilitation facilities may be inappropriate for those who have become tolerant or dependent while taking the drug as prescribed, as opposed to recreational use. Such inpatient referrals may be traumatic for these individuals.

Prognosis

Refer to Post-Acute Withdrawal Syndrome (PAWS).

A 2006 meta-analysis found evidence for the efficacy of stepped care: minimal intervention (e.g. send an advisory letter, or meet a large number of patients to advise discontinuation), followed by systematic tapered discontinuation alone without augmentation if the first try was unsuccessful. Cognitive behavioural therapy improved discontinuation success rates for panic disorder, melatonin for insomnia, and flumazenil or sodium valproate for general long-term benzodiazepine use. A ten-year follow-up found that more than half of those who had successfully withdrawn from long-term use were still abstinent two years later and that if they were able to maintain this state at two years, they were likely to maintain this state at the ten-year follow-up. One study found that after one year of abstinence from long-term use of benzodiazepines, cognitive, neurological and intellectual impairments had returned to normal.

Those who had a prior psychiatric diagnosis had a similar success rate from a gradual taper at a two-year follow-up. Withdrawal from benzodiazepines did not lead to an increased use of antidepressants.

Withdrawal Process

It can be too difficult to withdraw from short- or intermediate-acting benzodiazepines because of the intensity of the rebound symptoms felt between doses. Moreover, short-acting benzodiazepines appear to produce a more intense withdrawal syndrome. For this reason, discontinuation is sometimes carried out by first substituting an equivalent dose of a short-acting benzodiazepine with a longer-acting one like diazepam or chlordiazepoxide. Failure to use the correct equivalent amount can precipitate a severe withdrawal reaction. Benzodiazepines with a half-life of more than 24 hours include chlordiazepoxide, diazepam, clobazam, clonazepam, chlorazepinic acid, ketazolam, medazepam, nordazepam, and prazepam. Benzodiazepines with a half-life of less than 24 hours include alprazolam, bromazepam, brotizolam, flunitrazepam, loprazolam, lorazepam, lormetazepam, midazolam, nitrazepam, oxazepam, and temazepam. The resultant equivalent dose is then gradually reduced.

The consensus is to reduce dosage gradually over several weeks, e.g. 4 or more weeks for diazepam doses over 30 mg/day, with the rate determined by the person’s ability to tolerate symptoms. The recommended reduction rates range from 50% of the initial dose every week or so, to 10-25% of the daily dose every 2 weeks. For example, the reduction rate used in the Heather Ashton protocol calls for eliminating 10% of the remaining dose every two to four weeks, depending on the severity and response to reductions with the final dose at 0.5 mg dose of diazepam or 2.5 mg dose of chlordiazepoxide. For most people, discontinuation over 4-6 weeks or 4-8 weeks is suitable. A prolonged period of reduction over many months should be avoided to prevent the withdrawal process from becoming a “morbid focus” for the person.

Duration

After the last dose has been taken, the acute phase of the withdrawal generally lasts for about two months although withdrawal symptoms, even from low-dose use, can persist for six to twelve months gradually improving over that period, however, clinically significant withdrawal symptoms may persist for years, although gradually declining.

A clinical trial of patients taking the benzodiazepine alprazolam for as short as eight weeks triggered protracted symptoms of memory deficits which were still present up to eight weeks after cessation of alprazolam.

Protracted Withdrawal Syndrome

Protracted withdrawal syndrome (or Post-Acute Withdrawal Syndrome, PAWS) refers to symptoms persisting for months or even years. A significant minority of people withdrawing from benzodiazepines, perhaps 10% to 15%, experience a protracted withdrawal syndrome which can sometimes be severe. Symptoms may include tinnitus, psychosis, cognitive deficits, gastrointestinal complaints, insomnia, paraesthesia (tingling and numbness), pain (usually in limbs and extremities), muscle pain, weakness, tension, painful tremor, shaking attacks, jerks, dizziness and blepharospasm and may occur even without a pre-existing history of these symptoms. Tinnitus occurring during dose reduction or discontinuation of benzodiazepines is alleviated by recommencement of benzodiazepines. Dizziness is often reported as being the withdrawal symptom that lasts the longest.

A study testing neuropsychological factors found psychophysiological markers differing from normal, and concluded that protracted withdrawal syndrome was a genuine iatrogenic condition caused by the long-term use. The causes of persisting symptoms are a combination of pharmacological factors such as persisting drug induced receptor changes, psychological factors both caused by the drug and separate from the drug and possibly in some cases, particularly high dose users, structural brain damage or structural neuronal damage. Symptoms continue to improve over time, often to the point where people eventually resume their normal lives, even after years of incapacity.

A slow withdrawal rate significantly reduces the risk of a protracted or severe withdrawal state. Protracted withdrawal symptoms can be punctuated by periods of good days and bad days. When symptoms increase periodically during protracted withdrawal, physiological changes may be present, including dilated pupils as well as an increase in blood pressure and heart rate. The change in symptoms has been proposed to be due to changes in receptor sensitivity for GABA during the process of tolerance reversal. A meta-analysis found cognitive impairments in many areas due to benzodiazepine use show improvements after six months of withdrawal, but significant impairments in most areas may be permanent or may require more than six months to reverse.

Protracted symptoms continue to fade over a period of many months or several years. There is no known cure for protracted benzodiazepine withdrawal syndrome except time, however, the medication flumazenil was found to be more effective than placebo in reducing feelings of hostility and aggression in patients who had been free of benzodiazepines for 4-266 weeks. This may suggest a role for flumazenil in treating protracted benzodiazepine withdrawal symptoms.

Epidemiology

The severity and length of the withdrawal syndrome is likely determined by various factors, including rate of tapering, length of use and dosage size, and possible genetic factors. Those who have a prior history of withdrawing from benzodiazepines may have a sensitized or kindled central nervous system leading to worsening cognition and symptomatology, and making each subsequent withdrawal period worse.

Special Populations

Paediatrics

A neonatal withdrawal syndrome, sometimes severe, can occur when the mother had taken benzodiazepines, especially during the third trimester. Symptoms include hypotonia, apnoeic spells, cyanosis, impaired metabolic responses to cold stress, and seizures. The neonatal benzodiazepine withdrawal syndrome has been reported to persist from hours to months after birth.

A withdrawal syndrome is seen in about 20% of paediatric intensive care unit children after infusions with benzodiazepines or opioids. The likelihood of having the syndrome correlates with total infusion duration and dose, although duration is thought to be more important. Treatment for withdrawal usually involves weaning over a 3- to 21-day period if the infusion lasted for more than a week. Symptoms include tremors, agitation, sleeplessness, inconsolable crying, diarrhoea and sweating. In total, over fifty withdrawal symptoms are listed in this review article. Environmental measures aimed at easing the symptoms of neonates with severe abstinence syndrome had little impact, but providing a quiet sleep environment helped in mild cases.

Pregnancy

Discontinuing benzodiazepines or antidepressants abruptly due to concerns of teratogenic effects of the medications has a high risk of causing serious complications, so is not recommended. For example, abrupt withdrawal of benzodiazepines or antidepressants has a high risk of causing extreme withdrawal symptoms, including suicidal ideation and a severe rebound effect of the return of the underlying disorder if present. This can lead to hospitalisation and potentially, suicide. One study reported one-third of mothers who suddenly discontinued or very rapidly tapered their medications became acutely suicidal due to ‘unbearable symptoms’. One woman had a medical abortion, as she felt she could no longer cope, and another woman used alcohol in a bid to combat the withdrawal symptoms from benzodiazepines. Spontaneous abortions may also result from abrupt withdrawal of psychotropic medications, including benzodiazepines. The study reported physicians generally are not aware of the severe consequences of abrupt withdrawal of psychotropic medications such as benzodiazepines or antidepressants.

Elderly

A study of the elderly who were benzodiazepine dependent found withdrawal could be carried out with few complications and could lead to improvements in sleep and cognitive abilities. At 52 weeks after successful withdrawal, a 22% improvement in cognitive status was found, as well as improved social functioning. Those who remained on benzodiazepines experienced a 5% decline in cognitive abilities, which seemed to be faster than that seen in normal aging, suggesting the longer the intake of benzodiazepines, the worse the cognitive effects become. Some worsening of symptoms were seen in the first few months of benzodiazepine abstinence, but at a 24-week follow-up, elderly subjects were clearly improved compared to those who remained on benzodiazepines. Improvements in sleep were seen at the 24- and 52-week follow-ups. The authors concluded benzodiazepines were not effective in the long term for sleep problems except in suppressing withdrawal-related rebound insomnia. Improvements were seen between 24 and 52 weeks after withdrawal in many factors, including improved sleep and several cognitive and performance abilities. Some cognitive abilities, which are sensitive to benzodiazepines, as well as age, such as episodic memory, did not improve. The authors, however, cited a study in younger patients who at a 3.5-year follow-up showed no memory impairments and speculated that certain memory functions take longer to recover from chronic benzodiazepine use and further improvements in elderly people’s cognitive function may occur beyond 52 weeks after withdrawal. The reason it took 24 weeks for improvements to be seen after cessation of benzodiazepine use was due to the time it takes the brain to adapt to the benzodiazepine-free environment.

At 24 weeks, significant improvements were found, including accuracy of information processing improved, but a decline was seen in those who remained on benzodiazepines. Further improvements were noted at the 52-week follow-up, indicating ongoing improvements with benzodiazepine abstinence. Younger people on benzodiazepines also experience cognitive deterioration in visual-spatial memory but are not as vulnerable as the elderly to the cognitive effects. Improved reaction times were noted at 52 weeks in elderly patients free from benzodiazepines. This is an important function in the elderly, especially if they drive a car due to the increased risk of road traffic accidents in benzodiazepine users. At the 24-week follow-up, 80% of people had successfully withdrawn from benzodiazepines. Part of the success was attributed to the placebo method used for part of the trial which broke the psychological dependence on benzodiazepines when the elderly patients realised they had completed their gradual reduction several weeks previously and had only been taking placebo tablets. This helped reassure them they could sleep without their pills.

The authors also warned of the similarities in pharmacology and mechanism of action of the newer nonbenzodiazepine Z drugs.

The elimination half-life of diazepam and chlordiazepoxide, as well as other long half-life benzodiazepines, is twice as long in the elderly compared to younger individuals. Many doctors do not adjust benzodiazepine dosage according to age in elderly patients.