Extending levodopa action: COMT inhibition.

P Martínez-Martín, C F O'Brien

Index: Neurology 50(6 Suppl 6) , S27-32; discussion S44-8, (1998)

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Abstract

Degradation of levodopa in the periphery is known to be associated with motor fluctuations and dyskinesia in Parkinson's disease (PD) patients. The enzyme catechol-O-methyltransferase (COMT) is responsible for much of this degradation. Therefore, inhibiting COMT activity is one method of extending the action of levodopa. The new nitrocatechol-type COMT inhibitors entacapone, nitecapone, and tolcapone inhibit COMT in the periphery; tolcapone also inhibits COMT activity centrally. COMT inhibitors increase patients' duration of response to levodopa and reduce response fluctuations. Administration may prolong levodopa-induced dyskinesia, but peak-dose dyskinesia does not appear to increase. To reduce dyskinesia, the total daily dose of levodopa can be reduced.