Opicapone for Parkinson’s Disease

Opicapone was added to the Pharmaceutical Benefits Scheme (PBS) on 1 February 2023. Opicapone is indicated as adjunctive therapy to a levodopa-decarboxylase inhibitor combination in adults with Parkinson’s disease who experience end-of-dose motor fluctuations.

Opicapone is an inhibitor of the catechol-O-methyltransferase (COMT) enzyme. When dopa decarboxylase is inhibited (i.e. in patients taking benserazide or carbidopa), COMT becomes a major metabolising enzyme of levodopa. For these patients, opicapone increases levodopa availability in the central nervous system, improving its clinical effect.

A recent meta-analysis compared the safety and efficacy of opicapone (25mg and 50mg orally daily) to placebo in levodopa-treated patients with Parkinson’s disease. Opicapone was associated with reduced time spent in the OFF state and increased time spent in the ON state, including time without troublesome dyskinesia. Patients in the opicapone groups were also more likely to have their levodopa dose reduced. No significant differences were noted between opicapone and placebo regarding serious treatment-emergent adverse events and adverse events leading to study discontinuation.

Entacapone is another COMT inhibitor available in Australia. It requires administration with each levodopa dose, although fixed-dose combination tablets are available with levodopa and carbidopa. In comparison, opicapone has a long duration of action and can be administered once daily. Opicapone capsules should be swallowed whole on an empty stomach at least one hour before or after a levodopa dose.