Objective: To evaluate the effect of opicapone (OPC) 50 mg versus an additional levodopa (L-DOPA) dose of 100 mg in patients with Parkinson’s disease (PD) and early motor fluctuations receiving treatment regimens containing different daily L-DOPA doses.

Background: The L-DOPA equivalent daily dose (LEDD) conversion formulae are tools used to compare the equivalence of anti-PD medications.

Method: In the Korean ADOPTION study, patients with PD and early motor fluctuations treated with up to 600 mg of L-DOPA given 3–4 times daily were randomised to receive OPC 50 mg or an additional 100 mg L-DOPA dose for 4 weeks. The main endpoint was change from baseline in OFF-time. In this post-hoc analysis, patients’ home diaries were used to evaluate changes in OFF-time in the subgroup of patients receiving 300–400 mg/day L-DOPA at baseline plus OPC 50 mg and in the subgroup receiving >300 mg/day L-DOPA at baseline plus an additional dose of L-DOPA 100 mg.

Results: Of the 86 patients included in this subgroup analysis, 39 received OPC 50 mg and 47 L-DOPA 100 mg. At baseline, both L-DOPA total daily dose and LEDD were lower in the L-DOPA 300–400 mg/day plus OPC 50 mg group than in the L-DOPA >300 mg/day plus L-DOPA 100 mg. However, at Week 4, LEDD was similar between the two groups [Table 1]. The mean (±standard error) reduction in OFF-time was approximately three-fold greater for the OPC 50 mg than for the L-DOPA 100 mg group [Table 2; Figure 1], being -63.0 (14.6) minutes for patients treated with L-DOPA 300–400 mg/day plus OPC 50 mg, versus -22.1 (9.3) minutes for those receiving L-DOPA >300 mg/day plus L-DOPA 100 mg.

Conclusion: Despite similar LEDD, OPC demonstrated a significantly greater reduction in OFF-time when compared to an additional 100 mg L-DOPA dose. The effect of OPC appears to be LEDD independent, suggesting that caution should be exercised when employing LEDD to guide treatment decisions as this does not take into account the timing of each dose, onset, duration of therapeutic effect and individual responsiveness.

Table 1

Table 2

Figure 1

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MDS Abstracts - https://www.mdsabstracts.org/abstract/efficacy-of-opicapone-and-levodopa-with-different-levodopa-daily-doses-in-parkinsons-disease-patients-with-early-motor-fluctuations-findings-from-the-korean-adoption-study/