Comparative Pharmacology
Head-to-head clinical analysis: PARLODEL versus REQUIP XL.
Peer-Reviewed Evidence
Head-to-head clinical analysis: PARLODEL versus REQUIP XL.
PARLODEL vs REQUIP XL
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Dopamine D2 receptor agonist; inhibits prolactin secretion by binding to pituitary and hypothalamic D2 receptors.
Ropinirole is a non-ergoline dopamine agonist with high relative in vitro specificity and full intrinsic activity at the D2 subfamily of dopamine receptors, binding with higher affinity to D3 than to D2 or D4 receptor subtypes. The relevance of D3 receptor binding in Parkinson's disease is unknown.
Parkinson disease: initial 1.25 mg orally twice daily, increase by 2.5 mg/day every 2-4 weeks; usual range 15-30 mg/day. Hyperprolactinemia: initial 1.25-2.5 mg orally once daily, titrate to 2.5 mg twice daily; maintenance 2.5-15 mg/day.
Initial: 2 mg orally once daily for weeks 1-2, then titrate as needed; maintenance: 8-24 mg orally once daily.
None Documented
None Documented
Terminal elimination half-life: 12-14 hours (biphasic, initial half-life 6-8 hours); clinical context: steady-state achieved in 2-3 days.
Approximately 6 hours (range 4-8 hours) for ropinirole; terminal half-life in elderly or hepatic impairment may be prolonged up to 10-12 hours. Clinically, steady-state achieved within 2 days of dosing.
Renal: approximately 60% as metabolites, 6% as unchanged drug; biliary/fecal: approximately 40% as metabolites and unchanged drug.
Renal: 60% (mainly metabolites, <10% unchanged); fecal/biliary: 20%; total excretion accounts for >80% of dose.
Category C
Category C
Dopamine Agonist
Dopamine Agonist