Drug Monograph
Full clinical overview, indications, dosage references & safety notes.
Drug Monograph
Full clinical overview, indications, dosage references & safety notes.
Overview
Fluvoxamine (Luvox®) is a selective serotonin reuptake inhibitor (SSRI) that is uncommonly used in veterinary medicine compared with more established agents such as fluoxetine. It may be used in dogs and cats for behavioral disorders, although published veterinary data supporting its use are limited.
Fluvoxamine has a relatively slow onset of action, and several weeks (often up to 6–8 weeks) may be required before full therapeutic effects are observed. Because of limited clinical experience and evidence in animals, it is generally considered an alternative rather than a first-line SSRI.
Mechanism of Action (MOA): Fluvoxamine selectively inhibits the reuptake of serotonin in the central nervous system, increasing serotonin availability and enhancing its effects. It has minimal influence on dopamine or norepinephrine systems.
Indications
Fluvoxamine may be considered as an adjunctive treatment for behavioral disorders in dogs and cats, particularly when other SSRIs are not suitable or effective.
- Behavioral disorders: Used for management of anxiety-related conditions, including generalized anxiety and stress-related behaviors.
- Aggression: May be used in cases of inappropriate or pathologic aggression as part of a behavioral modification plan.
- Obsessive-compulsive disorders: Helps reduce stereotypic or repetitive behaviors (e.g., compulsive licking, tail chasing).
- Adjunct to behavior modification: Most effective when combined with environmental management and training strategies.
Dosage (Reference)
Dog
In dogs, fluvoxamine is used extra-label for behavioral conditions. Clinical response may take several weeks, and gradual dose adjustment is recommended based on response and tolerance.
| Clinical use | Route | Dose | Notes |
|---|---|---|---|
| Behavioral disorders (adjunct) | PO | 1–2 mg/kg once daily | Evaluate response after 3–8 weeks; taper gradually when discontinuing. |
• Full therapeutic effect may require several weeks (up to 8 weeks).
• Do not discontinue abruptly—gradual tapering is recommended.
• Adjust dose in patients with hepatic or renal impairment.
Cat
In cats, fluvoxamine is used cautiously due to limited available data. Lower doses are recommended, and monitoring for behavioral and gastrointestinal effects is important.
| Clinical use | Route | Dose | Notes |
|---|---|---|---|
| Behavioral disorders (adjunct) | PO | 0.25–0.5 mg/kg once daily | Small tablet sizes may limit accurate dosing without compounding. |
• Limited pharmacokinetic data available—use cautiously.
• Monitor closely for sedation, appetite changes, and GI signs.
• Gradual dose tapering required when discontinuing therapy.
Warnings & Precautions
Fluvoxamine should be used cautiously in veterinary patients due to limited clinical data and the potential for significant drug interactions.
- Contraindications: Do not use in patients with hypersensitivity to SSRIs or those receiving monoamine oxidase inhibitors (MAOIs).
- Serotonin syndrome: Risk increases when combined with other serotonergic drugs; avoid concurrent use.
- Hepatic and renal disease: Dose reduction may be required in patients with impaired organ function.
- Cardiac disease: Use cautiously in patients with severe cardiovascular disease.
- Delayed onset: Clinical improvement may take several weeks; not suitable for immediate effect.
- Withdrawal effects: Abrupt discontinuation may result in relapse or adverse effects; taper gradually.
Drug Interactions
Fluvoxamine has numerous clinically relevant drug interactions, primarily due to its effects on serotonin pathways and hepatic metabolism.
- MAO inhibitors (e.g., selegiline): Contraindicated due to high risk of serotonin syndrome.
- Serotonergic drugs (e.g., tramadol, trazodone, mirtazapine): Increased risk of serotonin syndrome.
- Benzodiazepines: May increase sedative effects and drug concentrations.
- Beta-blockers (e.g., propranolol, metoprolol): Increased plasma concentrations and enhanced effects.
- Tricyclic antidepressants: Increased risk of toxicity and serotonin syndrome.
- Theophylline: Increased plasma concentrations and risk of toxicity.
- Warfarin: Increased risk of bleeding.
Side Effects & Overdose
Side Effects
The adverse effect profile in dogs and cats is not fully established but is generally consistent with other SSRIs.
- Dogs: Anorexia, lethargy, gastrointestinal upset, anxiety, irritability, insomnia, hyperactivity, panting, or aggression.
- Cats: Sedation, decreased appetite, vomiting, diarrhea, behavioral changes, and altered elimination patterns.
Overdose
Overdose can result in significant neurologic and cardiovascular effects and requires prompt supportive care.
- CNS effects: Lethargy, tremors, ataxia, seizures, or coma.
- Gastrointestinal signs: Vomiting, diarrhea, hypersalivation.
- Cardiovascular effects: Hypotension, bradycardia or tachycardia.
- Serotonin syndrome: Hyperthermia, agitation, neuromuscular abnormalities.
- Management: Supportive care, decontamination if appropriate, and symptomatic treatment.
Key Notes
Practical clinical considerations for the use of fluvoxamine in dogs and cats:
- Limited use: Less commonly prescribed than other SSRIs due to limited veterinary evidence.
- Slow onset: May take several weeks before improvement is observed.
- Behavioral therapy: Should always be combined with behavior modification for best results.
- Dosing limitations: Tablet sizes may limit accurate dosing, especially in small cats.
- Monitoring: Regularly assess appetite, behavior, and signs of serotonin syndrome.
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