Comparative Pharmacology
Head-to-head clinical analysis: PAXIL CR versus SARAFEM.
Peer-Reviewed Evidence
Head-to-head clinical analysis: PAXIL CR versus SARAFEM.
PAXIL CR vs SARAFEM
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Paroxetine is a selective serotonin reuptake inhibitor (SSRI). It potentiates serotonergic activity in the CNS by inhibiting the reuptake of serotonin at the presynaptic neuronal membrane, resulting in increased serotonin concentrations in the synaptic cleft.
SARAFEM (fluoxetine) is a selective serotonin reuptake inhibitor (SSRI). It potentiates serotonergic activity in the CNS by inhibiting the reuptake of serotonin at the presynaptic neuronal membrane, enhancing serotonin effects in the synaptic cleft.
12.5-37.5 mg orally once daily in the morning; initial dose 12.5 mg/day, titrate by 12.5 mg/day at intervals of at least 1 week to maximum 50 mg/day.
10-20 mg orally once daily initially, may increase to 40 mg/day after 3 weeks if needed; maximum 80 mg/day
None Documented
None Documented
The terminal elimination half-life of paroxetine (PAXIL CR) is approximately 15-20 hours. This supports once-daily dosing and requires about 5-7 days to reach steady-state concentration.
Fluoxetine: 4-6 days after single dose, 4-16 days after chronic dosing; norfluoxetine: 4-16 days after single dose, up to 16-20 days after chronic dosing. The long half-life minimizes withdrawal symptoms and allows for once-weekly dosing.
Renal excretion accounts for approximately 64% of the administered dose, with 2% as unchanged parent drug and the remainder as metabolites. Fecal excretion accounts for about 36%, mostly as metabolites. Less than 1% is excreted in bile.
Primarily renal excretion of fluoxetine (10%) and its active metabolite norfluoxetine (7.5%) as unchanged drug; the remainder is excreted as conjugates and other metabolites. Approximately 2.5% is excreted in feces.
Category C
Category C
SSRI Antidepressant
SSRI Antidepressant