What is Fluvoxamine?

Introduction

Fluvoxamine, sold under the brand name Luvox among others, is an antidepressant of the selective serotonin reuptake inhibitor (SSRI) class which is used primarily for the treatment of depression disorder and obsessive-compulsive disorder (OCD). It is also used to treat anxiety disorders, such as panic disorder, social anxiety disorder, and post-traumatic stress disorder.

Fluvoxamine’s side-effect profile is very similar to other SSRIs: constipation, gastrointestinal problems, headache, anxiety, irritation, sexual problems, dry mouth, sleep problems and a risk of suicide at the start of treatment by lifting the psychomotor inhibition, but these effects appear to be significantly weaker than with other SSRIs (except gastrointestinal side-effects). The tolerance profile also appears to be quite superior than other SSRIs, despite its age.

Anti-inflammatory effects of fluvoxamine are being researched to determine if it can be used to treat COVID-19. It is not approved by the US Federal Drug Administration (FDA) for treatment of any infection.

Brief History

Fluvoxamine was developed by Kali-Duphar, part of Solvay Pharmaceuticals, Belgium, now Abbott Laboratories, and introduced as Floxyfral in Switzerland in 1983. It was approved by the FDA in 1994, and introduced as Luvox in the US. In India, it is available, among several other brands, as Uvox by Abbott. It was one of the first SSRI antidepressants to be launched, and is prescribed in many countries to patients with major depression. It was the first SSRI, a non-TCA drug, approved by the FDA specifically for the treatment of OCD. At the end of 1995, more than ten million patients worldwide had been treated with fluvoxamine. Fluvoxamine was the first SSRI to be registered for the treatment of obsessive compulsive disorder in children by the FDA in 1997. In Japan, fluvoxamine was the first SSRI to be approved for the treatment of depression in 1999 and was later in 2005 the first drug to be approved for the treatment of social anxiety disorder. Fluvoxamine was the first SSRI approved for clinical use in the United Kingdom.

Medical Uses

In many countries (e.g. Australia, the UK, and Russia) it is commonly used for major depressive disorder. Fluvoxamine is also approved in the United States for OCD, and social anxiety disorder. In Japan it is also approved to treat OCD, social anxiety disorder (SAD) and major depressive disorder (MDD). Fluvoxamine is indicated for children and adolescents with OCD. The drug works long-term, and retains its therapeutic efficacy for at least one year. It has also been found to possess some analgesic properties in line with other SSRIs and tricyclic antidepressants.

There is tentative evidence that fluvoxamine is effective for social phobia in adults. Fluvoxamine is also effective for generalised anxiety disorder (GAD), SAD, panic disorder and separation anxiety disorder in children and adolescents. There is tentative evidence that fluvoxamine may help some people with negative symptoms of chronic schizophrenia.

Adverse Effects

Gastrointestinal side effects are more common in those receiving fluvoxamine than with other SSRIs. Otherwise, fluvoxamine’s side-effect profile is very similar to other SSRIs.

Common (1-10% Incidence) Adverse Effects

  • Nausea.
  • Vomiting.
  • Weight loss.
  • Yawning.
  • Loss of appetite.
  • Agitation.
  • Nervousness.
  • Anxiety.
  • Insomnia.
  • Somnolence (drowsiness).
  • Tremor.
  • Restlessness.
  • Headache.
  • Dizziness.
  • Palpitations.
  • Tachycardia (high heart rate).
  • Abdominal pain.
  • Dyspepsia (indigestion).
  • Diarrhoea.
  • Constipation.
  • Hyperhidrosis (excess sweating).
  • Asthenia (weakness).
  • Malaise.
  • Sexual dysfunction (including delayed ejaculation, erectile dysfunction, decreased libido, etc.).
  • Xerostomia (dry mouth).

Uncommon (0.1-1% Incidence) Adverse Effects

  • Arthralgia.
  • Hallucination.
  • Confusional state.
  • Extrapyramidal side effects (e.g. dystonia, parkinsonism, tremor, etc.).
  • Orthostatic hypotension.
  • Cutaneous hypersensitivity reactions (e.g. oedema [buildup of fluid in the tissues], rash, pruritus).

Rare (0.01-0.1% Incidence) Adverse Effects

  • Mania.
  • Seizures.
  • Abnormal hepatic (liver) function.
  • Photosensitivity (being abnormally sensitive to light).
  • Galactorrhoea (expulsion of breast milk unrelated to pregnancy or breastfeeding).

Unknown Frequency Adverse Effects

  • Hyperprolactinaemia (elevated plasma prolactin levels leading to galactorrhoea, amenorrhoea [cessation of menstrual cycles], etc.).
  • Bone fractures.
  • Glaucoma.
  • Mydriasis.
  • Urinary incontinence.
  • Urinary retention.
  • Bed-wetting.
  • Serotonin syndrome: A potentially fatal condition characterised by abrupt onset muscle rigidity, hyperthermia (elevated body temperature), rhabdomyolysis, mental status changes (e.g. coma, hallucinations, agitation), etc.
  • Neuroleptic malignant syndrome – practically identical presentation to serotonin syndrome except with a more prolonged onset.
  • Akathisia – a sense of inner restlessness that presents itself with the inability to stay still.
  • Paraesthesia.
  • Dysgeusia.
  • Haemorrhage.
  • Withdrawal symptoms.
  • Weight changes.
  • Suicidal ideation and behaviour.
  • Violence towards others.
  • Hyponatraemia.
  • Syndrome of inappropriate antidiuretic hormone secretion.
  • Ecchymoses.

Interactions

Fluvoxamine inhibits the following cytochrome P450 enzymes:

  • CYP1A2 (strongly) which metabolises agomelatine, amitriptyline, caffeine, clomipramine, clozapine, duloxetine, haloperidol, imipramine, phenacetin, tacrine, tamoxifen, theophylline, olanzapine, etc.
  • CYP3A4 (moderately) which metabolises alprazolam, aripiprazole, clozapine, haloperidol, quetiapine, pimozide, ziprasidone, etc.
  • CYP2D6 (weakly) which metabolises aripiprazole, chlorpromazine, clozapine, codeine, fluoxetine, haloperidol, olanzapine, oxycodone, paroxetine, perphenazine, pethidine, risperidone, sertraline, thioridazine, zuclopenthixol, etc.[43]
  • CYP2C9 (moderately) which metabolises nonsteroidal anti-inflammatory drugs, phenytoin, sulfonylureas, etc.
  • CYP2C19 (strongly) which metabolises clonazepam, diazepam, phenytoin, etc.
  • CYP2B6 (weakly) which metabolises bupropion, cyclophosphamide, sertraline, tamoxifen, valproate, etc.

By so doing, fluvoxamine can increase serum concentration of the substrates of these enzymes.

The plasma levels of oxidatively metabolised benzodiazepines (e.g. triazolam, midazolam, alprazolam and diazepam) are likely to be increased when co-administered with fluvoxamine. However the clearance of benzodiazepines metabolised by glucuronidation (e.g. lorazepam, oxazepam, temazepam) is unlikely to be affected by fluvoxamine. It appears that benzodiazepines metabolised by nitro-reduction (clonazepam, nitrazepam) are unlikely to be affected by fluvoxamine. Using fluvoxamine and alprazolam together can increase alprazolam plasma concentrations. If alprazolam is co-administered with fluvoxamine, the initial alprazolam dose should be reduced to the lowest effective dose.

Fluvoxamine and ramelteon co-administration is not indicated.

Fluvoxamine has been observed to increase serum concentrations of mirtazapine, which is mainly metabolised by CYP1A2, CYP2D6, and CYP3A4, by three- to four-fold in humans. Caution and adjustment of dosage as necessary are warranted when combining fluvoxamine and mirtazapine.

Fluvoxamine seriously affects the pharmacokinetics of tizanidine and increases the intensity and duration of its effects. Because of the potentially hazardous consequences, the concomitant use of tizanidine with fluvoxamine, or other potent inhibitors of CYP1A2, should be avoided.

Fluvoxamine’s interaction with St John’s wort can lead to increased serotonin levels and potentially lead to serotonin syndrome.

Pharmacology

Fluvoxamine is a potent selective serotonin reuptake inhibitor with around 100-fold affinity for the serotonin transporter over the norepinephrine transporter. It has negligible affinity for the dopamine transporter or any other site, with the sole exception of the σ1 receptor. It behaves as a potent agonist at this receptor and has the highest affinity (36 nM) of any SSRI for doing so. This may contribute to its antidepressant and anxiolytic effects and may also afford it some efficacy in treating the cognitive symptoms of depression. Unlike some other SSRI, fluvoxamine’s metabolites are pharmacologically neutral.

Society and Culture

Manufacturers include BayPharma, Synthon, and Teva, among others. Luvox was notably used by Eric Harris, one of the Columbine shooters.

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