A Randomized, double-blind, placebo-controlled study comparing the efficacy, safety and tolerability of levodopa-carbidopa versus placebo in patients with X-linked dystonia-parkinsonism (XDP).

BACKGROUND: XDP is an X-linked recessive disorder characterized by parkinsonism and dystonia described among Filipinos. Oral medications are frequently ineffective. Lately, DBS have been promising. However these are not generally available or affordable for the vast majority of patients. We then decided to evaluate the effectiveness of levodopa-carbidopa for XDP.
OBJECTIVE: To compare the efficacy, safety and tolerability of levodopa-carbidopa vs. placebo in XDP patients.
METHODS: After informed consent and randomization, the BFM and the UPDRS parts III and IV were performed at baseline and monthly up to 6 months. Patients were randomized to receive either levodopa-carbidopa at a starting dose of 125 mg levodopa/ day in 2 divided doses or corresponding placebo. Gradual uptitration was done to a maximum of 1000 mg levodopa/ day or until side effects appeared.
Homogeneity of the characteristics of patients in the 2 groups was determined using Independent t-test and Chi-square test. To determine the significance of changes in the efficacy parameters within each group, Wilcoxon Matched Pairs Signed Ranks Test was used. To compare the scores of the different efficacy parameters of the 2 groups, Mann Whitney U Test was applied to the data. A p≤0.050 was considered significant.
RESULTS: A total of 107 patients were recruited. There were 13 screen failures, and 94 were subsequently enrolled. The baseline characteristics (age, duration of illness, baseline BFM and UPDRS (motor) scores were not significant between levodopa and placebo (age in years: 47 + 9.35 vs. 50 + 9.51; duration of illness in years 6.3 + 7 vs. 6.2 + 5.2; BFM score: 32.8 + 24.5 vs. 28.4 + 26.5; UPDRS score 29.9 + 20.7 vs. 34.8 + 26.8).
There was a decrease in BFM scores from baseline to all follow-up periods in patients given levodopa but were statistically significant only on visit 2 and visit 9. In the placebo group, decrease in scores was also observed in some observation periods but no statistical significance was shown. A comparison of the 2 groups showed that the magnitude of decrease in the levodopa group was statistically greater than the placebo group on the second visit. There were no significant differences observed in all other follow-up periods. Both groups showed a decrease in UPDRS scores but significant decrease was observed in visits 2, 5, 6, 7, 9 of the levodopa group. While in the placebo group, a significant decrease was observed only on visit 2. Comparison of the 2 groups did not show any significant differences.
There were 17 patients from the levodopa group who reported adverse events (most common: increased involuntary movements, nausea/ vomiting/ dizziness, headache, and generalized weakness. In the placebo group, there were 11 patients (most common: increased involuntary movements, abdominal pain). There were 9 patients who dropped out (levodopa: 4, placebo: 5).
CONCLUSION: There was a significant decrease in the BFM and UPDRS scores in XDP patients given levodopa compared to placebo. Levodopa is a safe and effective drug that may be considered in patients with XDP.
NOTE: This study was supported by an unrestricted grant by Torrent Pharma Philippines, Inc.