Effect of MK-458 (HPMC) in Parkinson's disease previously untreated with dopaminergic drugs. A double-blind, placebo-controlled multicenter study

Ninety-four patients with early Parkinson's disease were investigated in a double-blind, placebo-controlled evaluation of MK-458 [hydroxypropyl methylcellulose/lactose matrix (HPMC)], a sustained release formulation of a novel naphthoxazine compound with selective D-2 dopamine receptor agonism. Patients were previously untreated with dopaminergic drugs. Efficacy was assessed by clinical rating scales and by patient self-evaluation. MK-458 (HPMC) caused a significant decrease in most parkinsonian symptoms. Though disability rating scores were lowered by the drug, the scores did not differ significantly from placebo. However, statistically significant improvement occurred with MK-458 (HPMC) on both the physician and the patient global assessments. Adverse reactions such as nausea and vomiting, sedation, confusion, and hallucinations occurred more with MK-458 (HPMC) than with placebo. MK-458 (HPMC) possesses antiparkinsonian efficacy in early Parkinson's disease; however, side-effects are frequently associated with its use. Selective D-2 receptor agonists, such as MK-458 (HPMC), may not be the ideal treatment as monotherapy for Parkinson's disease.