Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
PROZAC WEEKLY vs LUVOX
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Selective serotonin reuptake inhibitor (SSRI); potentiates serotonergic activity by blocking reuptake of serotonin at the presynaptic neuronal membrane.
Selective serotonin reuptake inhibitor (SSRI); increases serotonergic activity by blocking reuptake of serotonin into presynaptic neurons.
Major depressive disorder,Obsessive-compulsive disorder,Bulimia nervosa,Panic disorder
Obsessive-compulsive disorder (OCD),Social anxiety disorder,Panic disorder,Premenstrual dysphoric disorder (PMDD),Bulimia nervosa,Post-traumatic stress disorder (PTSD)
90 mg orally once weekly
Initial dose 50 mg orally once daily at bedtime, titrated by 50 mg increments every 4-7 days to effective dose; usual therapeutic range 100-300 mg/day divided once daily (at bedtime) or twice daily if tolerated. Maximum dose 300 mg/day.
Fluoxetine: 4-6 days after single dose, 4-6 days (extended to 7-9 days with chronic dosing due to autoinhibition of CYP2D6); norfluoxetine: 9-31 days. Steady state achieved after 2-4 weeks.
The terminal elimination half-life is approximately 15-20 hours but may be prolonged in patients with hepatic impairment or with advanced age. Steady-state is typically achieved within 7-10 days of chronic dosing.
Hepatic via CYP2D6, CYP2C9, and CYP3A4; active metabolite norfluoxetine.
Primarily hepatic via CYP1A2; minor pathways via CYP2D6; active metabolites minimal.
Renal excretion of metabolites (primarily fluoxetine glucuronide and norfluoxetine glucuronide) accounts for approximately 80% of elimination; fecal excretion accounts for approximately 15%.
Approximately 94% of a dose is excreted in urine, mostly as conjugated and oxidized metabolites, with 2% as unchanged drug. Fecal excretion accounts for less than 4%.
Approximately 94.5% bound to plasma proteins, including albumin and alpha-1-acid glycoprotein.
Approximately 80% bound to plasma proteins, primarily albumin and alpha-1-acid glycoprotein.
12-43 L/kg (average ~25 L/kg). Large Vd indicates extensive tissue distribution, including brain and fat; contributes to prolonged elimination.
The apparent volume of distribution is about 4.7 L/kg, indicating extensive extravascular distribution and tissue binding, which contributes to its long half-life.
Oral: ~90% (not significantly affected by food). Weekly formulation: same bioavailability as daily dosing.
Oral bioavailability is approximately 53% after a single dose, with no significant food effect. Bioavailability may be higher under steady-state conditions due to saturation of first-pass metabolism.
No dose adjustment required for GFR ≥15 m L/min; insufficient data for GFR <15 m L/min, use with caution.
No dose adjustment required for mild to moderate renal impairment (Cr Cl ≥20 m L/min). Avoid use in severe renal impairment (Cr Cl <20 m L/min) due to lack of data.
Child-Pugh Class A: no adjustment; Class B: initiate at 20 mg/day (immediate-release) or use alternative; Class C: contraindicated or use with extreme caution.
Child-Pugh Class A: no dose adjustment; Child-Pugh Class B: reduce dose by 50% (start 25 mg/day, titrate cautiously); Child-Pugh Class C: contraindicated.
Not approved for use in pediatric patients; safety and efficacy not established.
Children (8-17 years): start 25 mg orally once daily at bedtime; increase by 25 mg increments every 4-7 days to target dose; for OCD: 25-200 mg/day; maximum 200 mg/day. Weight not routinely used; dosing based on age and response.
Initiate with 20 mg/day (immediate-release) and increase cautiously; monitor for hyponatremia and SIADH; PROZAC WEEKLY not recommended due to limited data.
Start 25 mg orally once daily at bedtime; titrate slowly (increases of 25 mg every 1-2 weeks); usual maximum 200 mg/day due to increased sensitivity and risk of hyponatremia.
Increased risk of suicidal thinking and behavior in children, adolescents, and young adults with major depressive disorder and other psychiatric disorders.
Increased risk of suicidal thinking and behavior in children, adolescents, and young adults with major depressive disorder and other psychiatric disorders.
Clinical worsening and suicide risk,Serotonin syndrome,Mania/hypomania,Seizures,Altered platelet function,Angle-closure glaucoma,Hyponatremia,QT prolongation,Sexual dysfunction
Suicidality risk in young patients,Serotonin syndrome,Activation of mania/hypomania,Seizure risk,Abnormal bleeding,Angle-closure glaucoma,Hyponatremia,QT prolongation,Sexual dysfunction,Discontinuation syndrome
Concomitant use with MAOIs,Concomitant use with pimozide or thioridazine,Known hypersensitivity to fluoxetine
Concomitant use with MAOIs,Concomitant use with triptans,Hypersensitivity to fluvoxamine or any excipient,Pregnancy (relative)
Grapefruit and grapefruit juice may increase fluoxetine levels; avoid large amounts. No specific dietary restrictions, but take with food if GI upset occurs.
Avoid grapefruit juice as it inhibits CYP1A2 and can increase fluvoxamine serum concentrations, leading to toxicity. No other significant food interactions; however, taking with food may reduce GI upset.
First trimester: Crosses placenta; risk of major congenital malformations based on some studies (e.g., cardiovascular defects approx. 1.8% vs 1% baseline). Third trimester: Risk of persistent pulmonary hypertension of the newborn (PPHN) approx. 0.3% vs 0.1% baseline. Late trimester: Neonatal adaptation syndrome (irritability, feeding difficulties, respiratory distress) in ~30% exposed neonates.
First trimester: Increased risk of congenital malformations, particularly cardiac defects (RR ~1.5-2) based on observational studies; also associated with persistent pulmonary hypertension of the newborn (PPHN) (OR 2.1). Second/third trimester: Late pregnancy exposure may increase risk of preterm birth, low birth weight, and neonatal adaptation syndrome (e.g., respiratory distress, feeding difficulties, irritability).
Fluoxetine and norfluoxetine are excreted in breast milk. Infant serum concentrations are typically low (<10% maternal weight-adjusted dose). M/P ratio for fluoxetine ~0.8; norfluoxetine ~0.2. Cases of adverse effects (fussiness, poor feeding) are rare. Benefits may outweigh risks in moderate-severe depression.
Fluvoxamine is excreted into breast milk; M/P ratio ranges from 0.29 to 0.59. Relative infant dose is approximately 1.7% of maternal weight-adjusted dose. Low risk of adverse effects in breastfed infants; monitor for drowsiness, poor feeding, and weight gain. AAP classifies as compatible with breastfeeding.
No dose adjustment required based on PK studies in pregnancy. However, due to increased volume of distribution and clearance late in pregnancy, some patients may require a dose increase to maintain efficacy; monitor clinical response and adjust dose as needed.
Plasma levels of fluvoxamine may decrease during pregnancy due to increased volume of distribution and enhanced hepatic metabolism. Dose adjustment may be necessary; consider therapeutic drug monitoring to maintain efficacy. Usually, dose can be increased by 50-100% in third trimester, with gradual reduction postpartum to pre-pregnancy levels.
Fluoxetine has a long half-life (4-6 days; active metabolite norfluoxetine 4-16 days) allowing weekly dosing, but requires daily loading for 13 weeks before switching to weekly. Monitor for serotonin syndrome if co-prescribed with other serotonergic drugs. Abrupt discontinuation may cause withdrawal symptoms despite long half-life.
Luvox (fluvoxamine) is a selective serotonin reuptake inhibitor (SSRI) approved for obsessive-compulsive disorder (OCD) and social anxiety disorder. It has a short half-life (15-22 hours) and no active metabolites, making it suitable for patients with hepatic impairment. Monitor for serotonin syndrome, especially when co-prescribed with other serotonergic agents. Luvox is a potent inhibitor of CYP1A2, affecting metabolism of drugs like clozapine, olanzapine, theophylline, and tizanidine. Titrate slowly; start at 50 mg nightly and increase by 50 mg every 4-7 days to a max of 300 mg daily (divided for doses >100 mg). Discontinuation syndrome is common; taper gradually.
Take once weekly on the same day, typically 90 mg capsule. Do not crush or chew.,May take 4-8 weeks for full therapeutic effect.,Common side effects include nausea, insomnia, drowsiness, sweating, and sexual dysfunction.,Avoid alcohol as it may worsen side effects.,Contact doctor if rash, suicidal thoughts, or serotonin syndrome symptoms occur.,Do not stop abruptly; withdrawal effects possible.
Take Luvox exactly as prescribed, usually once daily at bedtime to minimize daytime drowsiness.,It may take several weeks to feel the full effect; do not stop abruptly without consulting your doctor.,Avoid grapefruit juice, which can increase Luvox levels and side effects.,Report any signs of serotonin syndrome (hallucinations, agitation, rapid heart rate, fever, muscle stiffness) immediately.,Do not drive or operate heavy machinery until you know how Luvox affects you, as it can cause drowsiness or dizziness.,Limit alcohol consumption; alcohol can worsen sedation and increase risk of side effects.,Store at room temperature, away from moisture and heat.
No interactions on record
"Tetracycline may inhibit the metabolism of Fluvoxamine via cytochrome P450 enzyme interference, leading to increased Fluvoxamine plasma concentrations. This elevation potentiates serotonergic effects and may precipitate serotonin syndrome, characterized by hyperthermia, autonomic instability, and neuromuscular abnormalities. Concurrent use requires careful monitoring for signs of toxicity such as agitation, confusion, and tachycardia."
"Dexlansoprazole, a proton pump inhibitor (PPI), may inhibit CYP1A2, the primary enzyme responsible for metabolizing fluvoxamine, a selective serotonin reuptake inhibitor (SSRI). This interaction can lead to increased plasma concentrations of fluvoxamine, potentiating its serotonergic effects and risk of dose-dependent adverse events such as nausea, somnolence, and serotonin syndrome. Clinicians should monitor for signs of fluvoxamine toxicity and consider dose adjustment when initiating or discontinuing dexlansoprazole."
"Afatinib, an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, and fluvoxamine, a selective serotonin reuptake inhibitor (SSRI), both undergo metabolism via CYP450 enzymes. Afatinib is a moderate inhibitor of CYP2D6 and may also inhibit CYP1A2 and CYP3A4, while fluvoxamine is a known inhibitor of CYP1A2 and CYP2C19. Coadministration can lead to increased fluvoxamine concentrations due to inhibition of its metabolism, potentially resulting in enhanced serotonergic effects such as serotonin syndrome, as well as increased adverse effects like nausea, dizziness, or QT prolongation."
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about PROZAC WEEKLY vs LUVOX, answered by our medical review team.
PROZAC WEEKLY is a SSRI Antidepressant that works by Selective serotonin reuptake inhibitor (SSRI); potentiates serotonergic activity by blocking reuptake of serotonin at the presynaptic neuronal membrane.. LUVOX is a SSRI Antidepressant that works by Selective serotonin reuptake inhibitor (SSRI); increases serotonergic activity by blocking reuptake of serotonin into presynaptic neurons.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between PROZAC WEEKLY and LUVOX depend on the specific clinical indication. These are both SSRI Antidepressant agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of PROZAC WEEKLY is: 90 mg orally once weekly. The standard adult dose of LUVOX is: Initial dose 50 mg orally once daily at bedtime, titrated by 50 mg increments every 4-7 days to effective dose; usual therapeutic range 100-300 mg/day divided once daily (at bedtime) or twice daily if tolerated. Maximum dose 300 mg/day.. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between PROZAC WEEKLY and LUVOX in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. PROZAC WEEKLY is classified as Category C. First trimester: Crosses placenta; risk of major congenital malformations based on some studies (e.g., cardiovascular defects approx. 1.8% vs 1% baseline). Third trimester: Risk of. LUVOX is classified as Category C. First trimester: Increased risk of congenital malformations, particularly cardiac defects (RR ~1.5-2) based on observational studies; also associated with persistent pulmonary hype. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.