Tag: Medication

What is Gepirone?

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Introduction

Gepirone, sold under the brand name Exxua, is a medication used for the treatment of major depressive disorder. It is taken orally.

Side effects of gepirone include dizziness, nausea, insomnia, abdominal pain, and dyspepsia (indigestion). Gepirone acts as a partial agonist of the serotonin 5-HT1A receptor. An active metabolite of gepirone, 1-(2-pyrimidinyl)piperazine, is an α2-adrenergic receptor antagonist. Gepirone is a member of the azapirone group of compounds.

Gepirone was synthesized by Bristol-Myers Squibb in 1986 and was developed and marketed by Fabre-Kramer Pharmaceuticals. It was approved for the treatment of major depressive disorder in the United States in September 2023. This came after the drug had been rejected by the US Food and Drug Administration (FDA) three times over two decades due to insufficient evidence of effectiveness.

Brief History

Gepirone was developed by Bristol-Myers Squibb in 1986, but was out-licensed to Fabre-Kramer in 1993. The FDA rejected approval for gepirone in 2002 and 2004. It was submitted for the preregistration (NDA) phase again in May 2007 after adding additional information from clinical trials as the FDA required in 2009. However, in 2012 it once again failed to convince the FDA of its qualities for treating anxiety and depression. In December 2015, the FDA once again gave gepirone a negative review for depression due to concerns of efficacy. However, in March 2016, the FDA reversed its decision and gave gepirone ER a positive review. Gepirone ER was finally approved for the treatment of major depressive disorder in the United States in September 2023.

Medical Uses

Gepirone is indicated for the treatment of major depressive disorder in adults. Of 15 clinical trials of gepirone for major depressive disorder submitted to the FDA, three were excluded for methodological reasons, three were deemed “failed” and “uninformative”, seven were deemed negative and did not demonstrate effectiveness, and two were deemed positive and did show effectiveness. Two positive trials are needed for FDA drug approval, with this being the case regardless of the number of negative trials. In the two positive trials of gepirone for depression, the drug significantly outperformed placebo in terms of depressive symptom reduction and showed effect sizes similar to those of other approved antidepressants. In both trials, gepirone reduced depressive symptoms by about 2.5 points more than placebo on the 52-point Hamilton Depression Rating Scale (17-item version or HAMD-17). The baseline depression scores in the trials ranged from 22.7 to 24.2 in the different patient groups.

Available Forms

Gepirone comes in the form of extended-release tablets of the hydrochloride salt, gepirone hydrochloride, in the strengths 18.2 mg, 36.3 mg, 54.5 mg, and 72.6 mg.

Side Effects

Side effects of gepirone include dizziness, nausea, insomnia, abdominal pain, and dyspepsia (indigestion).

Interactions

The CYP3A4 inhibitors ketoconazole and verapamil strongly increase exposure to gepirone, whereas lithium, paroxetine, and warfarin have no effect on exposure to gepirone. The CYP3A4 inducer rifampin profoundly decreases exposure to gepirone.

Pharmacology

Pharmacodynamics

Gepirone acts as a selective partial agonist of the 5-HT1A receptor. Unlike its relative buspirone, however, gepirone has greater efficacy in activating the 5-HT1A and has negligible affinity for the D2 receptor (30- to 50-fold lower in comparison to buspirone). However, similarly to buspirone, gepirone metabolises into 1-(2-pyrimidinyl)piperazine (1-PP), which is known to act as a potent antagonist of the α2-adrenergic receptor.

Pharmacokinetics

Absorption

The absolute bioavailability of gepirone is 14 to 17%. The time to peak concentrations of gepirone with the extended-release formulation is 6 hours. When taken with a high-fat meal, the time to peak levels decreases to 3 hours. A high-fat meal increases exposure to gepirone, with the effect increasing dependent on the amount of fat in the meal. Peak concentrations were increased by 27% with a low-fat meal, 55% with a medium-fat meal, and 62% with a high-fat meal, while area-under-the-curve levels of gepirone were increased by 14% with a low-fat meal, 22% with a medium-fat meal, and 32 to 37% with a high-fat meal. The effect was similar for the metabolites of gepirone, 1-PP and 3′-hydroxygepirone (3′-OH-gepirone).

Distribution

The apparent volume of distribution of gepirone is approximately 94.5 L. The plasma protein binding of gepirone in vitro is 72% and is independent of concentration. The plasma protein binding of 3′-OH-gepirone is 59% and of 1-PP is 42%.

Metabolism

Gepirone is metabolised primarily by CYP3A4. Its major metabolites are 1-PP and 3′-OH-gepirone, both of which are pharmacologically active. These metabolites are present in the circulation at higher concentrations than gepirone.

Elimination

With a single oral dose of radiolabeled gepirone, 81% is recovered in urine and 13% is recovered in faeces as metabolites. About 60% of the gepirone is eliminated in urine within 24 hours.

The terminal half-life of gepirone as the extended-release form is approximately 5 hours.

Chemistry

Gepirone is a member of the azapirone group of compounds and is structurally related to buspirone, tandospirone, and other azapirones.

Society and Culture

Names

The brand name of gepirone is Exxua. Former tentative brand names which were never used included Ariza, Variza, and Travivo.

Research

Gepirone is under development for the treatment of decreased libido and generalized anxiety disorder. As of October 2023, it is in phase 3 clinical trials for these indications. The pro-sexual effects of gepirone appear to be independent of its antidepressant and anxiolytic effects.

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What is Fencamfamin?

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Introduction

Fencamfamin (INN), also known as fencamfamine or by the brand names Glucoenergan and Reactivan, is a stimulant which was developed by Merck in the 1960s.

Medical Uses

Fencamfamin is still used, though rarely, for treating depressive day-time fatigue, lack of concentration and lethargy, particularly in individuals who have chronic medical conditions, as its favourable safety profile makes it the most suitable drug in some cases.

Adverse Effects

Fencamfamin is well tolerated and causes minimal circulatory effects. Extended use may result in a dryness of the mouth.

Contraindications

Not to be used with heart diseases, angina pectoris and decompensated cardiac insufficiency, glaucoma, hyper-excitability and thyrotoxicosis or while treated with monoamine oxidase inhibitors.

Overdose

Symptoms of overdose are nausea, agitation and restlessness, dryness of the mouth, dizziness and tremor. In gross overdosage also associated with dyspnoea, tachycardia, disorientation and convulsions.

Research

In a study on slices of rat corpus striatum and substantia nigra fencamfamin acted as an indirect dopamine agonist. It released dopamine by a similar mechanism to amphetamines, but was ten times less potent than dexamphetamine at producing this effect. The main mechanism of action was instead inhibition of dopamine reuptake. Also unlike amphetamines, fencamfamin does not inhibit the action of monoamine oxidase enzymes. It was concluded that, at least in the models employed, the in vitro profile of fencamfamin is more similar to that of nomifensine, a reportedly pure uptake inhibitor, than to d-amphetamine.

In animal experiments on place preference fencamfamin produced a significant place preference only at the dose of 3.5 mg/kg. The experiments suggested a relation to dopamine D1 receptors, and also to opioid receptors in the reinforcement produced by fencamfamin, as place preference was blocked by the selective dopamine D1 antagonist SCH 23390 and by the opioid antagonist naloxone. A similar place preference, which was blocked by naloxone and by SCH 23390 and by raclopride, has been seen in a study on rats with drinking water. Animals treated with naloxone before the conditioning sessions showed a place aversion instead of the place preference found in saline-treated animals. Naloxone also reduced drinking. It was proposed that naloxone induced a state of frustrative nonreward. It was suggested that both dopamine and (endogenous) opioids are important for water-induced reinforcement. Possible interactions between these two neurotransmitter systems were discussed.

Synthesis

Fencamfamin may be synthesized in a straightforward fashion via the Diels-Alder reaction between cyclopentadiene and β-nitrostyrene (1-nitro-2-phenyl-ethene). The C=C double bond and the nitro-group in the resulting norcamphene derivative are then reduced to give the saturated norcamphane derivative. Finally, the amino-group is ethylated.

Although β-nitrostyrene is commercially available, it is also very easily prepared using the Henry Reaction between benzaldehyde and nitromethane.

The Diels-Alder reaction of β-nitrostyrene and cyclopentadiene is described in a number of early papers.

The reduction of the nitroalkene may be carried out sequentially. The alkene’s double bond is typically reduced using hydrogen and a transition metal catalyst like Ni or Pt, while the nitro group is reduced to the amine with a metal/acid combination, such as Fe/HCl. The reduction of both functional groups can also be achieved simultaneously by the use of Raney nickel, and this transformation has recently been optimized by Russian chemists.

Originally achieved under reductive amination conditions involving the reaction of the amine with acetaldehyde in the presence of Pt, ethylation of the amino-group has been improved by the use of Ra-Ni and ethanol.

The stereochemical consequences of the steps involved in the reaction sequence outlined above have been studied. Thus, the Diels-Alder cycloaddition leads to a product in which the nitro- and phenyl- groups are in a trans- relationship to each other. This product is actually a mixture of stereoisomers, in which the pair of enantiomers having the nitro- group in the endo- position and the phenyl- group in the exo- position predominates over the enantiomeric pair with exo-nitro and endo-phenyl groups. Although the isomeric composition of the Diels-Alder adduct itself does not seem to have been determined, Poos et al. reported a ratio of ~3:1 for the saturated un-ethylated amine derived from it. Novakov and co-workers, citing a thesis study, report that the corresponding ratio of endo-N-ethyl/exo-Φ : exo-N-ethyl/endo-Φ enantiomeric pairs is ~9:1 in fencamfamin itself.

This page is based on the copyrighted Wikipedia article < https://en.wikipedia.org/wiki/Fencamfamin >; it is used under the Creative Commons Attribution-ShareAlike 3.0 Unported License (CC-BY-SA). You may redistribute it, verbatim or modified, providing that you comply with the terms of the CC-BY-SA.

What is Dexmethylphenide?

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Introduction

Dexmethylphenidate, sold under the brand name Focalin among others, is a potent central nervous system (CNS) stimulant used to treat attention deficit hyperactivity disorder (ADHD) in those over the age of five years. It is taken by mouth. The immediate release formulation lasts up to five hours while the extended release formulation lasts up to twelve hours. It is the more active enantiomer of methylphenidate.

Common side effects include abdominal pain, loss of appetite, and fever. Serious side effects may include abuse, psychosis, sudden cardiac death, mania, anaphylaxis, seizures, and dangerously prolonged erection. Safety during pregnancy and breastfeeding is unclear. Dexmethylphenidate is a central nervous system (CNS) stimulant. How it works in ADHD is unclear.

Dexmethylphenidate was approved for medical use in the United States in 2001. It is available as a generic medication. In 2020, it was the 130th most commonly prescribed medication in the United States, with more than 4 million prescriptions.

Medical Uses

Dexmethylphenidate is used as a treatment for ADHD, usually along with psychological, educational, behavioural or other forms of treatment. It is proposed that stimulants help ameliorate the symptoms of ADHD by making it easier for the user to concentrate, avoid distraction, and control behaviour. Placebo-controlled trials have shown that once-daily dexmethylphenidate XR was effective and generally well tolerated.

Improvements in ADHD symptoms in children were significantly greater for dexmethylphenidate XR versus placebo. It also showed greater efficacy than osmotic controlled-release oral delivery system (OROS) methylphenidate over the first half of the laboratory classroom day but assessments late in the day favoured OROS methylphenidate.

Contraindications

Methylphenidate is contraindicated for individuals using monoamine oxidase inhibitors (e.g., phenelzine, and tranylcypromine), or individuals with agitation, tics, glaucoma, heart defects or a hypersensitivity to any ingredients contained in methylphenidate pharmaceuticals.

Pregnant women are advised to only use the medication if the benefits outweigh the potential risks. Not enough human studies have been conducted to conclusively demonstrate an effect of methylphenidate on foetal development. In 2018, a review concluded that it has not been teratogenic in rats and rabbits, and that it “is not a major human teratogen”.

Adverse Effects

Products containing dexmethylphenidate have a side effect profile comparable to those containing methylphenidate.

The most common side effects associated with methylphenidate (in standard and extended-release formulations) are appetite loss, dry mouth, anxiety/nervousness, nausea, and insomnia. Gastrointestinal adverse effects may include abdominal pain and weight loss. Nervous system adverse effects may include akathisia (agitation/restlessness), irritability, dyskinesia (tics), Oromandibular dystonia, lethargy (drowsiness/fatigue), and dizziness. Cardiac adverse effects may include palpitations, changes in blood pressure, and heart rate (typically mild), and tachycardia (rapid heart rate). Ophthalmologic adverse effects may include blurred vision caused by pupil dilatation and dry eyes, with less frequent reports of diplopia and mydriasis.

Smokers with ADHD who take methylphenidate may increase their nicotine dependence, and smoke more often than before they began using methylphenidate, with increased nicotine cravings and an average increase of 1.3 cigarettes per day.

There is some evidence of mild reductions in height with prolonged treatment in children. This has been estimated at 1 centimetre (0.4 in) or less per year during the first three years with a total decrease of 3 centimetres (1.2 in) over 10 years.

Hypersensitivity (including skin rash, urticaria, and fever) is sometimes reported when using transdermal methylphenidate. The Daytrana patch has a much higher rate of skin reactions than oral methylphenidate.

Methylphenidate can worsen psychosis in people who are psychotic, and in very rare cases it has been associated with the emergence of new psychotic symptoms. It should be used with extreme caution in people with bipolar disorder due to the potential induction of mania or hypomania. There have been very rare reports of suicidal ideation, but some authors claim that evidence does not support a link. Logorrhea is occasionally reported and visual hallucinations are very rarely reported. Priapism is a very rare adverse event that can be potentially serious.

US Food and Drug Administration-commissioned studies in 2011 indicate that in children, young adults, and adults, there is no association between serious adverse cardiovascular events (sudden death, heart attack, and stroke) and the medical use of methylphenidate or other ADHD stimulants.

Because some adverse effects may only emerge during chronic use of methylphenidate, a constant watch for adverse effects is recommended.

A 2018 Cochrane review found that methylphenidate might be associated with serious side effects such as heart problems, psychosis, and death. The certainty of the evidence was stated as very low.

The same review found tentative evidence that it may cause both serious and non-serious adverse effects in children.

Overdose

The symptoms of a moderate acute overdose on methylphenidate primarily arise from central nervous system overstimulation; these symptoms include: vomiting, nausea, agitation, tremors, hyperreflexia, muscle twitching, euphoria, confusion, hallucinations, delirium, hyperthermia, sweating, flushing, headache, tachycardia, heart palpitations, cardiac arrhythmias, hypertension, mydriasis, and dryness of mucous membranes. A severe overdose may involve symptoms such as hyperpyrexia, sympathomimetic toxidrome, convulsions, paranoia, stereotypy (a repetitive movement disorder), rhabdomyolysis, coma, and circulatory collapse. A methylphenidate overdose is rarely fatal with appropriate care. Following injection of methylphenidate tablets into an artery, severe toxic reactions involving abscess formation and necrosis have been reported.

Treatment of a methylphenidate overdose typically involves the administration of benzodiazepines, with antipsychotics, α-adrenoceptor agonists and propofol serving as second-line therapies.

Addiction and Dependence

Methylphenidate is a stimulant with an addiction liability and dependence liability similar to amphetamine. It has moderate liability among addictive drugs; accordingly, addiction and psychological dependence are possible and likely when methylphenidate is used at high doses as a recreational drug. When used above the medical dose range, stimulants are associated with the development of stimulant psychosis.

Biomolecular Mechanisms

Methylphenidate has the potential to induce euphoria due to its pharmacodynamic effect (i.e. dopamine reuptake inhibition) in the brain’s reward system. At therapeutic doses, ADHD stimulants do not sufficiently activate the reward system; consequently, when taken as directed in doses that are commonly prescribed for the treatment of ADHD, methylphenidate use lacks the capacity to cause an addiction.

Interactions

Methylphenidate may inhibit the metabolism of vitamin K anticoagulants, certain anticonvulsants, and some antidepressants (tricyclic antidepressants, and selective serotonin reuptake inhibitors). Concomitant administration may require dose adjustments, possibly assisted by monitoring of plasma drug concentrations. There are several case reports of methylphenidate inducing serotonin syndrome with concomitant administration of antidepressants.

When methylphenidate is coingested with ethanol, a metabolite called ethylphenidate is formed via hepatic transesterification, not unlike the hepatic formation of cocaethylene from cocaine and ethanol. The reduced potency of ethylphenidate and its minor formation means it does not contribute to the pharmacological profile at therapeutic doses and even in overdose cases ethylphenidate concentrations remain negligible.

Coingestion of alcohol (ethanol) also increases the blood plasma levels of d-methylphenidate by up to 40%.

Liver toxicity from methylphenidate is extremely rare, but limited evidence suggests that intake of β-adrenergic agonists with methylphenidate may increase the risk of liver toxicity.

Mode of Activity

Methylphenidate is a catecholamine reuptake inhibitor that indirectly increases catecholaminergic neurotransmission by inhibiting the dopamine transporter (DAT) and norepinephrine transporter (NET), which are responsible for clearing catecholamines from the synapse, particularly in the striatum and meso-limbic system. Moreover, it is thought to “increase the release of these monoamines into the extraneuronal space.”

Although four stereoisomers of methylphenidate (MPH) are possible, only the threo diastereoisomers are used in modern practice. There is a high eudysmic ratio between the SS and RR enantiomers of MPH. Dexmethylphenidate (d-threo-methylphenidate) is a preparation of the RR enantiomer of methylphenidate. In theory, D-TMP (d-threo-methylphenidate) can be anticipated to be twice the strength of the racemic product

Pharmacology

Dexmethylphenidate has a 4–6 hour duration of effect. A long-acting formulation, Focalin XR, which spans 12 hours is also available and has been shown to be as effective as DL (dextro-, levo-)-TMP (threo-methylphenidate) XR (extended release) (Concerta, Ritalin LA), with flexible dosing and good tolerability. It has also been demonstrated to reduce ADHD symptoms in both children and adults. d-MPH has a similar side-effect profile to MPH and can be administered without regard to food intake.

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What is Desoxypipradrol?

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Introduction

Desoxypipradrol, also known as 2-⁠diphenylmethylpiperidine (2-DPMP), is a drug developed by Ciba in the 1950s which acts as a norepinephrine-dopamine reuptake inhibitor (NDRI).

Brief History

Desoxypipradrol was developed by the pharmaceutical company CIBA (now called Novartis) in the 1950s, and researched for applications such as the treatment of narcolepsy and ADHD; however, it was dropped from development after the related drug methylphenidate was developed by the same company. Methylphenidate was felt to be the superior drug for treating ADHD due to its shorter duration of action and more predictable pharmacokinetics, and while desoxypipradrol was researched for other applications (such as facilitation of rapid recovery from anaesthesia), its development was not continued. The hydroxylated derivative pipradrol was, however, introduced as a clinical drug indicated for depression, narcolepsy and cognitive enhancement in organic dementia.

Chemistry

Desoxypipradrol is closely related on a structural level to the compounds methylphenidate and pipradrol, all three of which share a similar pharmacological action. Of these three piperidines, desoxypipradrol has the longest elimination half-life, as it is a highly lipophilic molecule lacking polar functional groups that are typically targeted by metabolic enzymes, giving it an extremely long duration of action when compared to most psychostimulants. Methylphenidate, on the other hand, is a short-acting compound, as it possesses a methyl-ester moiety that is easily cleaved, forming a highly polar acid group, while pipradrol is intermediate in duration, possessing a hydroxyl group which can be conjugated (e.g. with glucuronide) to increase its hydrophilicity and facilitate excretion, but no easily metabolised groups.

Detection in Biological Specimens

Desoxypipradrol may be quantitated in blood, plasma or urine by liquid chromatography-mass spectrometry to confirm a diagnosis of poisoning in hospitalised patients or to provide evidence in a medicolegal death investigation. Blood or plasma desoxypipradrol concentrations are expected to be in a range of 10–50 μg/L in persons using the drug recreationally, >100 μg/L in intoxicated patients and >600 μg/L in victims of acute overdosage

Legal Status

Desoxypipradrol’s structural similarity to pipradrol makes it possible that it would be considered a controlled substance analogue in several countries such as Australia and New Zealand.

China

As of October 2015 2-DPMP is a controlled substance in China.

United Kingdom

As of 04 November 2010, the UK Home Office announced a ban on the importation of 2-DPMP, following a recommendation from the Advisory Council on the Misuse of Drugs (ACMD).

Prior to the import ban, desoxypipradrol was sold as a ‘legal high’ in several products, most notably “Ivory wave”. Its use lead to several Emergency Department visits which prompted the UK government to commission a review from the ACMD. One man had ingested nearly 1 gram of the drug which may have been fatal without sedation with an anaesthetic dose of a benzodiazepine administered in accident and emergency.

The Advisory Council on the Misuse of Drugs stated in their report that:

“there are serious harms associated with 2-DPMP… typically prolonged agitation (lasting up to 5 days after drug use which is sometimes severe, requiring physical restraint), paranoia, hallucinations and myoclonus (muscle spasms/twitches).”

2-DPMP was due to become a class B drug on 28 March 2012, but the bill was scrapped as two steroids deemed not to be abusable were included in the bill but were later recommended to remain uncontrolled. There was a new discussion about its fate on 23 April 2012, where it was decided that the bill would be rewritten and 2-DPMP would still be banned. It was also decided that the bill would be a blanket ban of related chemicals.

Desoxypipradrol was eventually made a class B drug and placed in Schedule I on 13 June 2012. There were no recorded deaths from the drug between the banning of its import and the banning of its possession. “Esters and ethers of pipradrol” were controlled with the same amendment as class C drugs.

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What is Buspirone?

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Introduction

Buspirone, sold under the brand name Buspar, among others, is a medication primarily used to treat anxiety disorders, particularly generalised anxiety disorder. Benefits support its short-term use. It is taken orally (by mouth), and takes two to six weeks to be fully effective.

Refer to Azapirone.

Common side effects of buspirone include nausea, headaches, dizziness, and difficulty concentrating. Serious side effects may include movement disorders, serotonin syndrome, and seizures. Its use in pregnancy appears to be safe but has not been well studied, and use during breastfeeding has not been well studied. It is a serotonin 5-HT1A receptor agonist.

Buspirone was first made in 1968 and approved for medical use in the United States in 1986. It is available as a generic medication. In 2020, it was the 55th most-commonly prescribed medication in the United States, with more than 12 million prescriptions.

Brief History

Buspirone was first synthesized by a team at Mead Johnson in 1968 but was not patented until 1980. It was initially developed as an antipsychotic acting on the D2 receptor but was found to be ineffective in the treatment of psychosis; it was then used as an anxiolytic instead. In 1986, Bristol-Myers Squibb gained FDA approval for buspirone in the treatment of GAD. The patent expired in 2001, and buspirone is now available as a generic drug.

Medical Uses

Anxiety

Buspirone is used for the short-term and long-term treatment of anxiety disorders or symptoms of anxiety. It is generally preferred over benzodiazepines because it does not activate the receptors that make drugs like alprazolam addictive.

Buspirone has no immediate anxiolytic effects, and hence has a delayed onset of action; its full clinical effectiveness may require 2–4 weeks to manifest itself. The drug has been shown to be similarly effective in the treatment of generalised anxiety disorder (GAD) to benzodiazepines including diazepam, alprazolam, lorazepam, and clorazepate. Buspirone is not known to be effective in the treatment of other anxiety disorders besides GAD, although there is some limited evidence that it may be useful in the treatment of social phobia as an adjunct to selective serotonin reuptake inhibitors (SSRIs).

Other Uses

Sexual Dysfunction

There is some evidence that buspirone on its own may be useful in the treatment of hypoactive sexual desire disorder (HSDD) in women. Buspirone may also be effective in treating antidepressant-induced sexual dysfunction.

Miscellaneous

Buspirone is not effective as a treatment for benzodiazepine withdrawal, barbiturate withdrawal, or alcohol withdrawal/delirium tremens.

SSRI and SNRI antidepressants such as paroxetine and venlafaxine may cause jaw pain/jaw spasm reversible syndrome (although it is not common), and buspirone appears to be successful in treating bruxism on SSRI/SNRI-induced jaw clenching.

Contraindications

Buspirone has these contraindications:

  • Hypersensitivity to buspirone
  • Metabolic acidosis, as in diabetes
  • Should not be used with MAO inhibitors
  • Severely compromised liver and/or kidney function

Side Effects

Known side effects associated with buspirone include dizziness, headaches, nausea, tinnitus, and paraesthesia. Buspirone is relatively well tolerated, and is not associated with sedation, cognitive and psychomotor impairment, muscle relaxation, physical dependence, or anticonvulsant effects. In addition, buspirone does not produce euphoria and is not a drug of abuse. Dyskinesia, akathisia, myoclonus, parkinsonism, and dystonia were reported associated with buspirone. It is unclear if there is a risk of tardive dyskinesia or other movement disorders with buspirone.

Overdose

Buspirone appears to be relatively benign in cases of single-drug overdose, although no definitive data on this subject appear to be available. In one clinical trial, buspirone was administered to healthy male volunteers at a dosage of 375 mg/day, and produced side effects including nausea, vomiting, dizziness, drowsiness, miosis, and gastric distress. In early clinical trials, buspirone was given at dosages even as high as 2,400 mg/day, with akathisia, tremor, and muscle rigidity observed. Deliberate overdoses with 250 mg and up to 300 mg buspirone have resulted in drowsiness in about 50% of individuals. One death has been reported in a co-ingestion of 450 mg buspirone with alprazolam, diltiazem, alcohol, cocaine.

Interactions

Buspirone has been shown in vitro to be metabolized by the enzyme CYP3A4. This finding is consistent with the in vivo interactions observed between buspirone and these inhibitors or inducers of cytochrome P450 3A4 (CYP3A4), among others:

  • Itraconazole: Increased plasma level of buspirone
  • Rifampicin: Decreased plasma levels of buspirone
  • Nefazodone: Increased plasma levels of buspirone
  • Haloperidol: Increased plasma levels of buspirone
  • Carbamazepine: Decreased plasma levels of buspirone
  • Grapefruit: Significantly increases the plasma levels of buspirone.
  • Fluvoxamine: Moderately increase plasma levels of buspirone.
  • Elevated blood pressure has been reported when buspirone has been administered to patients taking monoamine oxidase inhibitors (MAOIs).

Pharmacology

Pharmacodynamics

Buspirone acts as an agonist of the serotonin 5-HT1A receptor with high affinity. It is a partial agonist of both presynaptic 5-HT1A receptors, which are inhibitory autoreceptors, and postsynaptic 5-HT1A receptors. It is thought that the main effects of buspirone are mediated via its interaction with the presynaptic 5-HT1A receptor, thus reducing the firing of serotonin-producing neurons. Buspirone also has lower affinities for the serotonin 5-HT2A, 5-HT2B, 5-HT2C, 5-HT6, and 5-HT7 receptors.

In addition to binding to serotonin receptors, buspirone is an antagonist of the dopamine D2 receptor with weak affinity. It preferentially blocks inhibitory presynaptic D2 autoreceptors, and antagonises postsynaptic D2 receptors only at higher doses. In accordance, buspirone has been found to increase dopaminergic neurotransmission in the nigrostriatal pathway at low doses, whereas at higher doses, postsynaptic D2 receptors are blocked and antidopaminergic effects such as hypoactivity and reduced stereotypy, though notably not catalepsy, are observed in animals. Buspirone has also been found to bind with much higher affinity to the dopamine D3 and D4 receptors, where it is similarly an antagonist.

A major metabolite of buspirone, 1-(2-pyrimidinyl)piperazine (1-PP), occurs at higher circulating levels than buspirone itself and is known to act as a potent α2-adrenergic receptor antagonist. This metabolite may be responsible for the increased noradrenergic and dopaminergic activity observed with buspirone in animals. In addition, 1-PP may play an important role in the antidepressant effects of buspirone. Buspirone also has very weak and probably clinically unimportant affinity for the α1-adrenergic receptor. However, buspirone has been reported to have shown “significant and selective intrinsic efficacy” at the α1-adrenergic receptor expressed in a “tissue- and species-dependent manner”.

Unlike benzodiazepines, buspirone does not interact with the GABAA receptor complex.

Pharmacokinetics

Buspirone has a low oral bioavailability of 3.9% relative to intravenous injection due to extensive first-pass metabolism. The time to peak plasma levels following ingestion is 0.9 to 1.5 hours. It is reported to have an elimination half-life of 2.8 hours, although a review of 14 studies found that the mean terminal half-life ranged between 2 and 11 hours, and one study even reported a terminal half-life of 33 hours. Buspirone is metabolised primarily by CYP3A4, and prominent drug interactions with inhibitors and inducers of this enzyme have been observed. Major metabolites of buspirone include 5-hydroxybuspirone, 6-hydroxybuspirone, 8-hydroxybuspirone, and 1-PP. 6-Hydroxybuspirone has been identified as the predominant hepatic metabolite of buspirone, with plasma levels that are 40-fold greater than those of buspirone after oral administration of buspirone to humans. The metabolite is a high-affinity partial agonist of the 5-HT1A receptor (Ki = 25 nM) similarly to buspirone, and has demonstrated occupancy of the 5-HT1A receptor in vivo. As such, it is likely to play an important role in the therapeutic effects of buspirone. 1-PP has also been found to circulate at higher levels than those of buspirone itself and may similarly play a significant role in the clinical effects of buspirone.

Chemistry

Buspirone is a member of the azapirone chemical class, and consists of azaspirodecanedione and pyrimidinylpiperazine components linked together by a butyl chain.

Analogues

Structural analogues of buspirone include other azapirones like gepirone, ipsapirone, perospirone, and tandospirone.

A number of analogues are recorded.

Synthesis

A number of more modern methods of synthesis have also been reported (list not exhaustive).

Alkylation of 1-(2-pyrimidyl)piperazine 20980-22-7 with 3-chloro-1-cyanopropane (4-chlorobutyronitrile) 628-20-6 gives 33386-14-0. the reduction of the nitrile group is performed either by catalytic hydrogenation or with LAH giving 33386-20-8. The primary amine is then reacted with 3,3-tetramethyleneglutaric anhydride 5662-95-3 in order to yield Buspirone (6).

Society and Culture

Generic names

Buspirone is the INNTooltip International Nonproprietary Name, BANTooltip British Approved Name, DCFTooltip Dénomination Commune Française, and DCITTooltip Denominazione Comune Italiana of buspirone, while buspirone hydrochloride is its USANTooltip United States Adopted Name, BANMTooltip British Approved Name, and JANTooltip Japanese Accepted Name.

Brand Name

Buspirone was primarily sold under the brand name Buspar. Buspar is currently listed as discontinued by the US Food and Drug Administration (FDA). In 2010, in response to a citizen petition, the FDA determined that Buspar was not withdrawn from sale for reasons of safety or effectiveness.

2019 Shortage

Due to interrupted production at a Mylan Pharmaceuticals plant in Morgantown, West Virginia, the US experienced a shortage of buspirone in 2019.

Research

Some tentative research supports other uses such as the treatment of depression and behavioural problems following brain damage.

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What is Brexpiprazole?

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Introduction

Brexpiprazole, sold under the brand name Rexulti among others, is a medication used for the treatment of major depressive disorder, schizophrenia, and agitation associated with dementia due to Alzheimer’s disease. It is an atypical antipsychotic.

The most common side effects include akathisia (a constant urge to move) and weight gain. The most common side effects among people with agitation associated with dementia due to Alzheimer’s disease include headache, dizziness, urinary tract infection, nasopharyngitis, and sleep disturbances (both somnolence and insomnia).

Brexpiprazole was developed by Otsuka and Lundbeck, and is considered to be a successor to aripiprazole (Abilify). It was approved for medical use in the United States in July 2015. A generic version was approved in August 2022. Brexpiprazole is the first treatment approved by the US Food and Drug Administration (FDA) for agitation associated with dementia due to Alzheimer’s disease.

Medical Uses

In the United States and Canada, brexpiprazole is indicated as an adjunctive therapy to antidepressants for the treatment of major depressive disorder and for the treatment of schizophrenia. In May 2023, the indication for brexpiprazole was expanded in the US to include the treatment of agitation associated with dementia due to Alzheimer’s disease.

In Australia and the European Union, brexpiprazole is indicated for the treatment of schizophrenia.

In 2020, it was approved in Brazil only as an adjunctive to the treatment of major depressive disorder.

Side Effects

The most common adverse events associated with brexpiprazole (all doses of brexpiprazole cumulatively greater than or equal to 5% vs. placebo) were upper respiratory tract infection (6.9% vs. 4.8%), akathisia (6.6% vs. 3.2%), weight gain (6.3% vs. 0.8%), and nasopharyngitis (5.0% vs. 1.6%). Brexpiprazole can cause impulse control disorders.

Pharmacology

Pharmacodynamics

Brexpiprazole acts as a partial agonist of the serotonin 5-HT1A receptor and the dopamine D2 and D3 receptors. Partial agonists have both blocking properties and stimulating properties at the receptor they bind to. The ratio of blocking activity to stimulating activity determines a portion of its clinical effects. Brexpiprazole has more blocking and less stimulating activity at the dopamine receptors than its predecessor, aripiprazole, which may decrease its risk for agitation and restlessness. Specifically, where aripiprazole has an intrinsic activity or agonist effect at the D2 receptor of 60%+, brexpiprazole has an intrinsic activity at the same receptor of about 45%. For aripiprazole, this means more dopamine receptor activation at lower doses, with blockade being reached at higher doses, while brexpiprazole has the inverse effect because a partial agonist competes with dopamine. Brexpiprazole has a high affinity for the 5-HT1A receptor, acting as a potent antagonist at 5-HT2A receptors, and a potent partial agonist at dopamine D2 receptors with lower intrinsic activity compared to aripiprazole. In vivo characterisation of brexpiprazole shows that it may act as a near-full agonist of the 5-HT1A receptor. This may further underlie a lower potential than aripiprazole to cause treatment-emergent, movement-related disorders such as akathisia due to the downstream dopamine release that is triggered by 5-HT1A receptor agonism. It is also an antagonist of the serotonin 5-HT2A, 5-HT2B, and 5-HT7 receptors, which may contribute to antidepressant effect. It also binds to and blocks the α1A-, α1B-, α1D-, and α2C-adrenergic receptors. The drug has negligible affinity for the muscarinic acetylcholine receptors, and hence has no anticholinergic effects. Although brexpiprazole has less affinity for H1 compared to aripiprazole, weight gain can occur.

Brief History

Clinical Trials

Brexpiprazole was in clinical trials for adjunctive treatment of major depressive disorder, adult attention deficit hyperactivity disorder, bipolar disorder, schizophrenia, and agitation associated with dementia due to Alzheimer’s disease.

Major Depressive Disorder

Phase II

The phase II multicenter, double-blind, placebo-controlled study randomized 429 adult MDD patients who exhibited an inadequate response to one to three approved antidepressant treatments (ADTs) in the current episode. The study was designed to assess the efficacy and safety of brexpiprazole as an adjunctive treatment to standard antidepressant treatment. The antidepressants included in the study were desvenlafaxine, escitalopram, fluoxetine, paroxetine, sertraline, and venlafaxine.

Phase III

A phase III study was in the recruiting stage: “Study of the Safety and Efficacy of Two Fixed Doses of OPC-34712 as Adjunctive Therapy in the Treatment of Adults With Major Depressive Disorder (the Polaris Trial)”. Its goal is “to compare the effect of brexpiprazole to the effect of placebo (an inactive substance) as add on treatment to an assigned FDA approved antidepressant treatment (ADT) in patients with major depressive disorder who demonstrate an incomplete response to a prospective trial of the same assigned FDA approved ADT”. Estimated enrolment was 1,250 volunteers.

Adult Attention Deficit Hyperactivity Disorder

  • Attention Deficit/Hyperactivity Disorder (STEP-A)

Schizophrenia

Phase I

  • Trial to Evaluate the Effects of OPC-34712 (brexpiprazole) on QT/QTc in Subjects With Schizophrenia or Schizoaffective Disorder

Phase II

  • A Dose-finding Trial of OPC-34712 in Patients With Schizophrenia

Phase III

  • Efficacy Study of OPC-34712 in Adults With Acute Schizophrenia (BEACON)
  • Study of the Effectiveness of Three Different Doses of OPC-34712 in the Treatment of Adults With Acute Schizophrenia (VECTOR)
  • A Long-term Trial of OPC-34712 in Patients With Schizophrenia

Agitation Associated with Dementia due to Alzheimer’s Disease

The effectiveness of brexpiprazole for the treatment of agitation associated with dementia due to Alzheimer’s disease was determined through two 12-week, randomized, double-blind, placebo-controlled, fixed-dose studies. In these studies, participants were required to have a probable diagnosis of Alzheimer’s dementia; have a score between 5 and 22 on the Mini-Mental State Examination, a test that detects whether a person is experiencing cognitive impairment; and exhibit the type, frequency, and severity of agitation behaviours that require medication. Trial participants ranged between 51 and 90 years of age.

Society and Culture

Legal Status

In January 2018, it was approved for the treatment of schizophrenia in Japan.

Economics

In November 2011, Otsuka Pharmaceutical and Lundbeck announced a global alliance. Lundbeck gave Otsuka an upfront payment of $200 million, and the deal includes development, regulatory and sales payments, for a potential total of $1.8 billion. Specifically for OPC-34712, Lundbeck will obtain 50% of net sales in Europe and Canada and 45% of net sales in the US from Otsuka.

Patents

  • US Patent 8,071,600
  • WIPO PCT/JP2006/317704
  • Canadian patent: 2620688

Research

Brexpiprazole was under development for the treatment of attention deficit hyperactivity disorder (ADHD) as an adjunct to stimulants, but was discontinued for this indication. It reached phase II clinical trials for this use prior to discontinuation.

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What is Setiptiline?

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Introduction

Setiptiline (brand name Tecipul), also known as teciptiline, is a tetracyclic antidepressant (TeCA) that acts as a noradrenergic and specific serotonergic antidepressant (NaSSA). It was launched in 1989 for the treatment of depression in Japan by Mochida.

Pharmacology

Pharmacodynamics

Setiptiline acts as a norepinephrine reuptake inhibitor, α2-adrenergic receptor antagonist, and serotonin receptor antagonist, likely at the 5-HT2 subtypes, as well as an H1 receptor inverse agonist/antihistamine.

Chemistry

Setiptiline has a tetracyclic structure and is a close analogue of mianserin and mirtazapine, with setiptiline being delta(13b,4a),4a-carba-mianserin, and mirtazapine being 6-azamianserin.

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What is Esmirtazapine?

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Introduction

Esmirtazapine (ORG-50,081) is a tetracyclic antidepressant drug which was under development by Organon for the treatment of insomnia and vasomotor symptoms (e.g. hot flashes) associated with menopause.

Outline

Esmirtazapine is the (S)-(+)-enantiomer of mirtazapine and possesses similar overall pharmacology, including inverse agonist actions at H1 and 5-HT2 receptors and antagonist actions at α2-adrenergic receptors.

Notably, esmirtazapine has a shorter half life of around 10 hours, compared to R-mirtazapine and racemic mixture, which has a half-life of 18-40 hours. Merck has run several studies on low dose (3 – 4.5 mg) esmirtazapine for the treatment of insomnia. It is attractive for treating insomnia since it is a potent H1-inhibitor and a 5-HT2A antagonist. Unlike low-dose mirtazapine, the half life (10 hours) is short enough that next-day sedation may be manageable, however, for people with CYP2D6 polymorphisms, which constitute a sizable fraction of the population, the half-life is expected to be quite a bit longer. Merck researchers claimed that the incidence of next-day sedation was not a problem in one of their studies, but this claim has been challenged (15% of patients complained of daytime sleepiness vs 3.5% in the placebo group).

In March 2010, Merck terminated its internal clinical development programme for esmirtazapine for hot flashes and insomnia, “for strategic reasons”.

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What is Aptazapine?

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Introduction

Aptazapine (developmental code name CGS-7525A) is a tetracyclic antidepressant (TeCA) that was assayed in clinical trials for the treatment of depression in the 1980s but was never marketed.

Outline

It is a potent α2-adrenergic receptor antagonist with ~10x the strength of the related compound mianserin and has also been shown to act as a 5-HT2 receptor antagonist and H1 receptor inverse agonist, while having no significant effects on the reuptake of serotonin or norepinephrine.

Based on its pharmacological profile, aptazapine may be classified as a noradrenergic and specific serotonergic antidepressant (NaSSA).

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What is Norepineprhine (Medication)?

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Introduction

Norepinephrine, also known as noradrenaline, is a medication used to treat people with very low blood pressure. It is the typical medication used in sepsis if low blood pressure does not improve following intravenous fluids. It is the same molecule as the hormone and neurotransmitter norepinephrine. It is given by slow injection into a vein.

Common side effects include headache, slow heart rate, and anxiety. Other side effects include an irregular heartbeat. If it leaks out of the vein at the site it is being given, norepinephrine can result in limb ischemia. If leakage occurs the use of phentolamine in the area affected may improve outcomes. Norepinephrine works by binding and activating alpha adrenergic receptors.

Norepinephrine was discovered in 1946 and was approved for medical use in the United States in 1950. It is available as a generic medication.

Medical Uses

Norepinephrine is used mainly as a sympathomimetic drug to treat people in vasodilatory shock states such as septic shock and neurogenic shock, while showing fewer adverse side-effects compared to dopamine treatment.

Mechanism of Action

It stimulates α1 and α2 adrenergic receptors to cause blood vessel contraction, thus increases peripheral vascular resistance and resulted in increased blood pressure. This effect also reduces the blood supply to gastrointestinal tract and kidneys. Norepinephrine acts on beta-1 adrenergic receptors, causing increase in heart rate and cardiac output. However, the elevation in heart rate is only transient, as baroreceptor response to the rise in blood pressure as well as enhanced vagal tone ultimately result in a sustained decrease in heart rate. Norepinephrine acts more on alpha receptors than the beta receptors.

Names

Norepinephrine is the INN (or International Nonproprietary Name) while noradrenaline is the BAN (British Approved Name).

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