Catechol-O-methyltransferase inhibitors in Parkinson's disease - Guidelines for effective use

Although orally administered levodopa is the mainstay treatment for Parkinson's disease, its use is often complicated by a fluctuating response. This may be improved by strategies that provide more constant dopaminergic stimulation. Catechol-O-methyltransferase (COMT) catalyses the O-methylation of catecholamines and other catechols, including levodopa and dopamine. Potent, selective inhibitors of COMT (entacapone and tolcapone) have been shown to increase the duration of response to levodopa without affecting the time to reach maximum concentration (t(max)) or maximum plasma concentration (C-max) of levodopa. To date, these inhibitors have been well tolerated in clinical trials. COMT inhibitors are a useful adjunct to levodopa in some patients with Parkinson's disease.