FLUOCET
Clinical safety rating: caution
Comprehensive clinical and safety monograph for FLUOCET (FLUOCET).
Fluoxetine is a selective serotonin reuptake inhibitor (SSRI) that potentiates serotonergic activity in the CNS by blocking the reuptake of serotonin into presynaptic neurons.
| Metabolism | Primarily hepatic, via CYP2D6 and CYP2C9 isoenzymes; active metabolite norfluoxetine. |
| Excretion | Renal: 80% as fluoxetine and its metabolites (60% as glucuronide conjugates, 20% as parent and norfluoxetine). Fecal: 15% (biliary). |
| Half-life | Fluoxetine: 4-6 days (single dose), 4-6 days (chronic); Norfluoxetine: 16 days. Clinical context: Steady state achieved after 4-5 weeks; extended half-life reduces withdrawal risk but prolongs washout. |
| Protein binding | 94.5% bound to albumin and alpha-1-acid glycoprotein. |
| Volume of Distribution | Vd: 12-42 L/kg (mean 27 L/kg). Clinical meaning: Extensive tissue distribution (CNS, lungs, liver). |
| Bioavailability | Oral: 60-80% (mean 72% due to first-pass metabolism). Food does not affect bioavailability significantly. |
| Onset of Action | Oral: 2-4 weeks for antidepressant effect; 4-8 weeks for full therapeutic response. IV: Not applicable. |
| Duration of Action | Oral: Effects persist for 2-3 weeks after discontinuation due to long half-life. Clinical notes: 5-week washout required before MAOI initiation. |
| Molecular Weight | 345.79 |
20 mg orally once daily in the morning.
| Dosage form | CREAM |
| Renal impairment | No dose adjustment required for GFR 15-50 mL/min; not recommended for GFR <15 mL/min. |
| Liver impairment | Child-Pugh A: 20 mg daily; Child-Pugh B: 10 mg daily; Child-Pugh C: not recommended. |
| Pediatric use | Children 8-18 years: 10 mg orally once daily; may increase to 20 mg after 2 weeks if needed. |
| Geriatric use | Initial dose 10 mg orally once daily; increase to 20 mg with caution. |
| 1st trimester | Not recommended; associated with increased risk of congenital malformations, particularly cardiovascular defects and neural tube defects. Risk of spontaneous abortion may be increased. |
| 2nd trimester | Avoid; may cause fetal renal impairment, oligohydramnios, and potential for premature closure of ductus arteriosus. |
| 3rd trimester | Avoid; high risk of premature closure of ductus arteriosus, persistent pulmonary hypertension of the newborn, and oligohydramnios. May prolong labor and increase risk of maternal hemorrhage. |
Clinical note
Comprehensive clinical and safety monograph for FLUOCET (FLUOCET).
| Placental transfer | Crosses placenta extensively; fetal concentrations reach 70-100% of maternal serum levels. |
| Breastfeeding | Fluocet (fluoxetine) is excreted into breast milk in low levels; however, due to the long half-life of its active metabolite, norfluoxetine, accumulation and adverse effects in the breastfed infant, such as irritability, poor feeding, and colic, are possible. Use only if clearly needed and monitor infant for signs of toxicity. |
■ FDA Black Box Warning
Increased risk of suicidal thinking and behavior in children, adolescents, and young adults with major depressive disorder and other psychiatric disorders.
| Serious Effects |
Hypersensitivity to fluoxetine or any excipientConcurrent use with MAOIs (including linezolid or methylene blue) within 14 daysConcurrent use with pimozide or thioridazineQT interval prolongation or congenital long QT syndrome
| Precautions | Serotonin syndrome, Suicidality in pediatric patients, Bleeding risk (especially with NSAIDs/aspirin), Activation of mania/hypomania, QT prolongation (caution in electrolyte disturbances, bradycardia), Seizures, Angle-closure glaucoma, Hyponatremia, Sexual dysfunction, Discontinuation syndrome |
| Food/Dietary | No significant food interactions are reported for fluoxetine. However, grapefruit juice may increase fluoxetine concentrations via CYP3A4 inhibition; avoid excessive consumption. Alcohol may potentiate CNS depression; advise avoidance. |
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| Lactation Rating | L3 (Moderately Safe) - use with caution |
| Teratogenic Risk | Fluoxetine use in the first trimester is associated with a small increased risk of congenital cardiac malformations (odds ratio ~1.2). Exposure in the third trimester may cause persistent pulmonary hypertension of the newborn (PPHN) and neonatal adaptation syndrome (irritability, feeding difficulties, respiratory distress). Late pregnancy exposure also increases risk of preterm birth and lower birth weight. |
| Fetal Monitoring | Maternal: Monitor for mood stabilisation, side effects (nausea, insomnia, anxiety), serotonin syndrome, and signs of hyponatremia. Fetal/Neonatal: Ultrasound for fetal growth and anatomy; neonatal assessment for PPHN and withdrawal symptoms (temperature, respiratory rate, feeding). |
| Fertility Effects | Fluoxetine may cause sexual dysfunction (decreased libido, delayed ejaculation, anorgasmia) in both men and women, potentially impairing fertility. In animal studies, high doses have shown reduced fertility, but human data are limited. No evidence of permanent infertility. |
| Clinical Pearls | FLUOCET is a brand name for fluoxetine, a selective serotonin reuptake inhibitor (SSRI). Monitor for serotonin syndrome when coadministered with other serotonergic agents. Use with caution in patients with hepatic impairment; dose reduction may be necessary. Due to its long half-life (4-6 days, with active metabolite norfluoxetine), washout periods of at least 5 weeks are needed before initiating MAOIs. Abrupt discontinuation may cause withdrawal symptoms; taper gradually. |
| Patient Advice | Take fluoxetine exactly as prescribed; do not stop suddenly without consulting your doctor. · It may take several weeks to feel the full benefit; do not get discouraged if you do not notice improvement immediately. · Avoid alcohol while taking this medication. · Contact your doctor immediately if you experience suicidal thoughts, worsening depression, or unusual changes in behavior. · Report any signs of serotonin syndrome: agitation, hallucinations, fast heart rate, fever, muscle stiffness, twitching, or diarrhea. · If you miss a dose, take it as soon as you remember unless it is close to your next dose; do not double up. · Notify your doctor if you are pregnant, planning to become pregnant, or breastfeeding. |