Usage
Fluvoxamine is primarily prescribed for the treatment of Obsessive-Compulsive Disorder (OCD) in adults and children (8 years and older). It’s also used for Major Depressive Disorder (MDD), although it’s not the first-line treatment. Other off-label uses include social anxiety disorder, panic disorder, bulimia nervosa, and post-traumatic stress disorder (PTSD).
Fluvoxamine is classified as a Selective Serotonin Reuptake Inhibitor (SSRI).
It works by increasing the amount of serotonin, a neurotransmitter, in the brain. Serotonin helps regulate mood, sleep, appetite, and other functions.
Alternate Names
Fluvoxamine maleate is the generic name. Brand names include Luvox, Luvox CR (extended-release), and various others depending on the region.
How It Works
Pharmacodynamics: Fluvoxamine selectively inhibits the reuptake of serotonin in the presynaptic neuron, increasing its concentration in the synaptic cleft. This enhances serotonergic neurotransmission, which is believed to be responsible for its therapeutic effect in OCD and depression. It has minimal affinity for other receptors, including histaminergic, adrenergic, muscarinic, or dopaminergic receptors.
Pharmacokinetics:
- Absorption: Fluvoxamine is well-absorbed orally, even with food.
- Metabolism: Extensively metabolized in the liver, primarily by CYP1A2 and to a lesser extent by CYP2D6 and CYP2C9.
- Elimination: Primarily eliminated via renal excretion of metabolites. The elimination half-life is approximately 13-15 hours for the immediate-release formulation and 17-22 hours for the extended-release formulation.
Mode of Action: At the molecular level, fluvoxamine binds to the serotonin transporter (SERT) on the presynaptic neuron, blocking the reuptake of serotonin. This increases the extracellular serotonin concentration and its effect on postsynaptic receptors.
Elimination Pathways: Primarily renal excretion.
Dosage
Standard Dosage
Adults:
- OCD: Initial dose is 50 mg once daily at bedtime. The dose may be increased in 50 mg increments every 4-7 days as tolerated, up to a maximum of 300 mg/day. Doses above 100 mg/day should be divided and given twice daily.
- MDD: The recommended starting dose is 50-100mg once daily in the evening. This can be increased gradually up to a maximum of 300 mg/day, based on individual response.
- Other Conditions: Dosing varies depending on the specific condition.
Children:
- OCD (8-11 years): Initial dose is 25 mg once daily at bedtime. The dose may be increased in 25 mg increments every 4-7 days as tolerated, up to a maximum of 200 mg/day.
- OCD (12-17 years): Initial dose is 25 mg once daily at bedtime. The dose may be increased in 25 mg increments every 4-7 days, as tolerated, up to a maximum of 300 mg/day.
- Doses above 50 mg/day should be divided and given twice daily.
Special Cases:
- Elderly Patients: Start with a lower dose and titrate slowly, monitoring closely for side effects.
- Patients with Renal Impairment: For moderate to severe impairment (GFR < 50 mL/min), start with a lower dose and titrate cautiously.
- Patients with Hepatic Dysfunction: Start with a low dose and increase slowly with careful monitoring.
- Patients with Comorbid Conditions: Dosage adjustments may be needed depending on the specific comorbidity.
Clinical Use Cases
Fluvoxamine is not typically used for intubation, surgical procedures, mechanical ventilation, ICU use, or emergency situations.
Dosage Adjustments
Dose adjustments may be required for patients with hepatic or renal impairment, based on individual patient response and tolerability.
Side Effects
Common Side Effects
Nausea, insomnia, headache, dizziness, drowsiness, anxiety, sexual dysfunction, dry mouth, sweating, tremor, anorexia, diarrhea, constipation.
Rare but Serious Side Effects
Serotonin syndrome, seizures, hyponatremia, bleeding disorders, suicidal ideation (especially in younger patients), mania/hypomania, angle-closure glaucoma, neuroleptic malignant syndrome-like reactions.
Long-Term Effects
Potential long-term effects are not well-established, but may include sexual dysfunction, weight changes, and sleep disturbances.
Adverse Drug Reactions (ADR)
Clinically significant ADRs include serotonin syndrome, seizures, and severe hyponatremia, requiring immediate medical intervention.
Contraindications
Hypersensitivity to fluvoxamine, concurrent use of MAOIs (or within 14 days of stopping MAOIs), concurrent use of tizanidine, thioridazine, pimozide, or alosetron.
Drug Interactions
MAOIs, tizanidine, thioridazine, pimozide, alosetron, tricyclic antidepressants, other SSRIs, SNRIs, lithium, warfarin, benzodiazepines (e.g., alprazolam, diazepam), theophylline, clozapine, and drugs metabolized by CYP1A2, CYP2C9, and CYP2D6. Alcohol should be avoided.
Pregnancy and Breastfeeding
Fluvoxamine is Pregnancy Category C. It’s generally not recommended during pregnancy unless the benefits outweigh the risks. It’s present in breast milk, so its use during breastfeeding should be carefully considered.
Drug Profile Summary
- Mechanism of Action: Selective serotonin reuptake inhibitor.
- Side Effects: Nausea, insomnia, headache, dizziness, sexual dysfunction, serotonin syndrome (rare).
- Contraindications: Hypersensitivity, concurrent MAOI use, tizanidine, thioridazine, pimozide, alosetron.
- Drug Interactions: MAOIs, TCAs, SSRIs, SNRIs, lithium, warfarin, certain antipsychotics.
- Pregnancy & Breastfeeding: Category C; use with caution.
- Dosage: Adults: 50-300 mg/day; Children: 25-200/300 mg/day (depending on age).
- Monitoring Parameters: Monitor for mood changes, suicidal ideation, and side effects. Periodic liver function tests may be considered.
Popular Combinations
Fluvoxamine is sometimes used in combination with other antidepressants or other psychiatric medications. However, these combinations should be used with caution and close monitoring.
Precautions
General precautions include screening for medical conditions, assessing for suicidal risk, and monitoring for drug interactions. Precautions for specific populations include careful monitoring of elderly patients and those with hepatic or renal impairment. Patients should avoid alcohol and be cautious when operating machinery.
FAQs
Q1: What is the recommended dosage for Fluvoxamine?
A: Adults: Initial 50 mg at bedtime, increasing as needed to a maximum of 300 mg/day. Children: 25 mg at bedtime, increasing as needed to a maximum of 200 mg/day (8-11 years) or 300 mg/day (12-17 years).
Q2: What are the common side effects of Fluvoxamine?
A: Nausea, insomnia, headache, dizziness, drowsiness, dry mouth, sexual dysfunction.
Q3: Is Fluvoxamine safe during pregnancy?
A: Pregnancy Category C; generally not recommended unless benefits outweigh risks.
Q4: What are the serious side effects of Fluvoxamine?
A: Serotonin syndrome, seizures, hyponatremia, suicidal ideation, mania/hypomania.
Q5: How does Fluvoxamine interact with other medications?
A: Interacts with MAOIs, tizanidine, thioridazine, pimozide, alosetron, some antidepressants, lithium, warfarin, and other drugs metabolized by certain CYP enzymes.
Q6: What is the mechanism of action of Fluvoxamine?
A: Selectively inhibits serotonin reuptake.
Q7: Can Fluvoxamine be used in children?
A: Yes, for OCD in children 8 years and older.
Q8: What should be monitored in patients taking Fluvoxamine?
A: Mood changes, suicidal thoughts, adverse reactions, and potential drug interactions. Consider monitoring liver function.
Q9: How long does it take for Fluvoxamine to work?
A: It can take several weeks (4-6 weeks or longer) for Fluvoxamine to reach full therapeutic effect.
Q10: What should patients do if they miss a dose of Fluvoxamine?
A: Take the missed dose as soon as remembered, unless it’s close to the next dose. Do not double the dose.
