Comparative Pharmacology
Head-to-head clinical analysis: DOSTINEX versus REQUIP XL.
Peer-Reviewed Evidence
Head-to-head clinical analysis: DOSTINEX versus REQUIP XL.
DOSTINEX vs REQUIP XL
Comparing the clinical profiles, pharmacokinetic behaviors, and safety indices of these two therapeutic agents.
Cabergoline is a long-acting dopamine D2 receptor agonist that inhibits prolactin secretion by binding to D2 receptors on lactotroph cells in the anterior pituitary.
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.
0.25 mg orally twice weekly, with a minimum of 2 days between doses; may increase by 0.25 mg twice weekly every 4 weeks up to a maximum of 1 mg twice weekly.
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
The terminal elimination half-life is 63–69 hours in healthy volunteers and 79–115 hours in patients with hyperprolactinemia, allowing once- or twice-weekly dosing. The long half-life reflects slow dissociation from D2 receptors and enterohepatic recirculation.
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.
Cabergoline is extensively metabolized in the liver, primarily via CYP3A4. Elimination is predominantly fecal (60%) and renal (20%) as metabolites, with <4% as unchanged drug. Biliary excretion contributes to fecal elimination.
Renal: 60% (mainly metabolites, <10% unchanged); fecal/biliary: 20%; total excretion accounts for >80% of dose.
Category C
Category C
Dopamine Agonist
Dopamine Agonist