Pharmacokinetics and effect of food after oral administration of prolonged-release tablets of ropinirole hydrochloride in Japanese patients with Parkinson's disease.

Ropinirole hydrochloride, a dopamine receptor agonist with a non-ergot alkaloid structure, is highly selective for the dopamine D(2) /D(3) receptors. This study was conducted to evaluate the steady-state pharmacokinetics, safety and efficacy after repeated oral administration of prolonged-release tablets of ropinirole hydrochloride in the absence of L-dopa preparations in Japanese patients with Parkinson's disease (PD). This was a multicenter, open-label, uncontrolled study. The total duration of participation in the study ranged from 56 to 63 weeks. In the study, the plasma concentrations of ropinirole, its major metabolite SK&F104557 (N-depropyl ropinirole) and another metabolite SK&F89124 (ropinirole hydroxylated at the seventh position of the indole ring) were assessed. Safety based on adverse events, haematology, biochemistry, urinalysis and electrocardiography (ECG) (standard 12-lead ECG) were evaluated, and vital signs (blood pressure/pulse rate) were measured. Efficacy based on the Japanese version of Unified Parkinson's Disease Rating Scale (UPDRS) Parts III (motor) and II [activities of daily living (ADL)] as well as tolerability was evaluated. After repeated oral administration of prolonged-release tablets of ropinirole hydrochloride in Japanese patients with PD, ropinirole, SK&F104557 and low levels of SK&F89124 were detected in plasma. The trough concentrations of ropinirole and the two metabolites increased in proportion to the dose when ropinirole hydrochloride prolonged-release tablets were administered at doses ranging from 2 to 16 mg/day. The plasma exposure to ropinirole and its two metabolites after intake of normal diet was comparable to that in the fasting state. The most common adverse events (10% or more) were somnolence, nausea, constipation, hallucination and nasopharyngitis. Most adverse events were mild or moderate in severity, and with no death. During the treatment period, serious adverse events were reported in five patients. Efficacy analysis (LOCF) at the final endpoint up to week 16 demonstrated a mean (SD) change from baseline in the Japanese UPDRS III (motor) and II (ADL) scores of -11·3 (8·21) and -3·9 (3·22), respectively, and thereafter remained at similar levels until week 52. After administration of prolonged-release tablets of ropinirole hydrochloride in the absence of L-dopa preparations in Japanese patients with PD, the plasma pharmacokinetics of ropinirole and its metabolites was linear and not affected by food. Compared with the immediate-release (IR) tablet, the prolonged-release tablet can be administered to Japanese patients with PD at a reduced daily dose frequency and adjusted to the maintenance dose after fewer dose changes with a smaller diurnal variation in the plasma ropinirole concentration.