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Drugs, Supplies and Delivery
Fluoxetine
Fluoxetine is a selective serotonin reuptake inhibitor (SSRI) and one of the most widely prescribed antidepressants. Known by its brand name Prozac, fluoxetine is used to treat depression, anxiety disorders, and other psychiatric conditions. Its long half-life and active metabolite make it a unique option among SSRIs. This article synthesizes information from the British National Formulary (BNF), Lippincott Textbook of Pharmacology, and Lange Basic & Clinical Pharmacology to provide a detailed overview of fluoxetine, including its mechanism of action, therapeutic uses, dosing, side effects, precautions, drug interactions, and availability.
Fluoxetine selectively inhibits the reuptake of serotonin (5-HT) at the presynaptic neuronal membrane, increasing serotonin availability in the synaptic cleft. This enhances serotonergic neurotransmission, which is associated with improved mood and emotional regulation (Lippincott Textbook of Pharmacology). Fluoxetine also has a long half-life (~4–6 days) due to its active metabolite, norfluoxetine, which prolongs its therapeutic effects (Lange Basic & Clinical Pharmacology).
- Major Depressive Disorder (MDD):
- First-line treatment for acute episodes and maintenance therapy to prevent relapse (BNF).
- Obsessive-Compulsive Disorder (OCD):
- Reduces intrusive thoughts and compulsive behaviors.
- Bulimia Nervosa:
- Helps reduce binge-eating and purging behaviors.
- Panic Disorder:
- Effective in reducing the frequency and severity of panic attacks.
- Premenstrual Dysphoric Disorder (PMDD):
- Alleviates mood swings, irritability, and physical symptoms (Lange Basic & Clinical Pharmacology).
- Adults:
- Initial Dose: 20 mg once daily, preferably in the morning.
- Maintenance Dose: 20–60 mg daily; maximum 80 mg/day (rarely needed).
- Elderly or Hepatically Impaired Patients:
- Lower Initial Dose: 10 mg/day, adjusted based on response (BNF).
- Children (≥8 years):
- OCD: 10 mg/day, increased to 20 mg/day after 1–2 weeks (Lippincott).
Administration:
- Can be taken with or without food.
- Avoid abrupt discontinuation; taper gradually over weeks to prevent withdrawal symptoms (Lange Basic & Clinical Pharmacology).
- Common: Nausea, headache, insomnia, and dry mouth (BNF).
- Serious:
- Serotonin Syndrome: Agitation, hyperthermia, and autonomic instability (rare but life-threatening).
- QT Prolongation: Risk of arrhythmias, particularly at high doses.
- Hyponatremia: Especially in elderly patients (Lippincott).
- Suicidal Ideation: Increased risk in adolescents and young adults (Lange Basic & Clinical Pharmacology).
- Contraindications:
- Concurrent use of MAO inhibitors (risk of serotonin syndrome).
- Known hypersensitivity to fluoxetine or other SSRIs (BNF).
- Monitoring:
- Monitor for suicidal thoughts, especially during the initial weeks of treatment.
- Serum sodium levels in elderly patients (Lippincott).
- Pregnancy/Lactation:
- Use with caution; potential neonatal withdrawal or persistent pulmonary hypertension (PPHN) (Lange Basic & Clinical Pharmacology).
- MAO Inhibitors: Risk of serotonin syndrome; allow a 5-week washout period after stopping fluoxetine (BNF).
- QT-Prolonging Drugs (e.g., amiodarone, antipsychotics): Synergistic risk of arrhythmias.
- CYP2D6 Inhibitors (e.g., paroxetine): Increase fluoxetine levels; monitor for toxicity.
- NSAIDs/Anticoagulants: Elevated bleeding risk due to SSRI-induced platelet dysfunction (Lippincott).
Fluoxetine is the generic name. It is marketed under the brand name Prozac® in some regions. Generic formulations are widely available as:
- Tablets: 10 mg, 20 mg, 60 mg.
- Capsules: 10 mg, 20 mg, 40 mg.
- Oral Solution: 20 mg/5 mL (BNF).
