Opicapone for Parkinson's disease

Approved indication: Parkinson's disease
Ongentys (Maxx Pharma)
50 mg hard capsules

The mainstay in the drug treatment of Parkinson's disease is a combination of levodopa and a peripheral dopa decarboxylase inhibitor, such as benserazide or carbidopa. Most patients on levodopa therapy eventually develop motor fluctuations, particularly towards the end of the dose interval, due to the effect of levodopa wearing off - known as 'off' time. One approach to managing this problem is to add a catechol-O-methyltransferase (COMT) inhibitor to the treatment regimen. This reduces the peripheral metabolism of levodopa and therefore increases the amount of levodopa available to the brain. Entacapone is a reversible COMT inhibitor, which has been available in Australia for many years. Opicapone is a new long-acting reversible COMT inhibitor. It is approved for adults with Parkinson's disease, as an adjunct to levodopa, for end-of-dose motor fluctuations.

Opicapone is taken at night at least one hour before or after a dose of levodopa. Food reduces absorption. Although the elimination half-life of opicapone is approximately 1-2 hours, a single 50 mg dose will inhibit COMT for over 24 hours. As this will greatly increase levodopa concentrations, the dose of levodopa will need to be reduced or the dose interval extended when opicapone is added to treatment. Opicapone is contraindicated with monoamine oxidase inhibitors such as phenelzine, but it may be possible to use it with one of the monoamine oxidase inhibitors indicated for Parkinson's disease, such as selegiline. No dose adjustment is needed in kidney disease, but opicapone is not recommended for patients with liver disease.

Opicapone was compared to placebo as an adjunct to levodopa therapy in 427 patients who were experiencing at least 1.5 hours of off time each day. There was a double-blind period of 14-15 weeks after which all patients took open-label opicapone for one year. The daily doses of opicapone in the double-blind period were 25 mg (129 patients) and 50 mg (154 patients). At the end of the double-blind phase, these doses had reduced the off time by a mean of 102 minutes and 119 minutes. Only the effect of the 50 mg dose was statistically greater than the reduction of 65 minutes with placebo. The effect was maintained during the open-label period.¹

Another phase III trial enrolled patients with end-of-dose motor fluctuations, but also included treatment arms with entacapone (200 mg with each levodopa dose) and a 5 mg daily dose of opicapone. A total of 600 patients were randomly allocated across the five treatment groups. After a 14-15-week double-blind period, the greatest reduction in off time was in patients who took opicapone 50 mg daily. Their off time fell by a mean of 117 minutes compared with 96 minutes in the entacapone group and 56 minutes in the placebo group. Statistical tests showed that opicapone 50 mg was non-inferior to entacapone.²

Adding opicapone to levodopa increases the risk of dopaminergic adverse effects such as dyskinesia, hallucinations and postural hypotension. Hence the need to adjust the dose of levodopa. Dyskinesia was the most frequent adverse effect during both trials,^1,2 and was more common with opicapone 50 mg (16%) than entacapone 200 mg (8%).² Other adverse effects of opicapone included nausea, constipation and insomnia. In one of the trials, 12% of the patients taking opicapone 50 mg daily discontinued treatment because of adverse events.¹

The clinical trials show that opicapone 50 mg daily decreases off time and increases on time compared to placebo.^1,2 Although off time decreased by about one hour more than with placebo, at baseline patients were experiencing an average of more than six hours of off time. It is unclear how much opicapone improves their quality of life. The effect on disability was similar to placebo and the trials did not include patients with more severe disability. They also excluded patients with psychiatric or cardiovascular disease.^1,2 While the efficacy of opicapone and entacapone appear to be similar, entacapone has to be taken several times a day.

🅃 manufacturer provided the product information

The Transparency Score is explained in New drugs: transparency, Vol 37 No 1, Aust Prescr 2014;37:27.

At the time the comment was prepared, information about this drug was available on the websites of the Food and Drug Administration in the USA, the European Medicines Agency and the Therapeutic Goods Administration.

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