Comparative Pharmacology
Head-to-head clinical analysis: RISPERDAL versus ZYPREXA.
Peer-Reviewed Evidence
Head-to-head clinical analysis: RISPERDAL versus ZYPREXA.
RISPERDAL vs ZYPREXA
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Risperidone is a benzisoxazole atypical antipsychotic that antagonizes dopamine D2 and serotonin 5-HT2A receptors. It also blocks alpha1-adrenergic, alpha2-adrenergic, and histamine H1 receptors.
Olanzapine is an atypical antipsychotic that antagonizes dopamine D2 and serotonin 5-HT2A receptors, with higher affinity for 5-HT2A than D2. It also blocks histamine H1, alpha-1 adrenergic, and muscarinic M1 receptors.
2-8 mg orally once daily or divided twice daily; maximum 16 mg/day
5-10 mg orally once daily; may increase by 5 mg/day at intervals of at least 1 week; maximum 20 mg/day.
None Documented
None Documented
20 hours (parent drug), 23 hours (active metabolite 9-hydroxyrisperidone). Steady state reached in 5-6 days. Extended in elderly and hepatic/renal impairment.
Terminal elimination half-life ~30 hours (range 21–54 h) in adults, allowing once-daily dosing; steady-state reached in ~5–7 days. Half-life prolonged in elderly, females, and hepatic impairment.
Renal: 70% (30% as unchanged drug, 40% as metabolites), Fecal/Biliary: 14%
Primarily hepatic metabolism via CYP1A2 and CYP2D6; ~7% excreted unchanged in urine, ~57% in urine as metabolites, ~30% in feces (mostly metabolites).
Category C
Category C
Atypical Antipsychotic
Atypical Antipsychotic