High-dose versus low-dose inhaled levodopa (CVT-301) in patients with Parkinson disease for the treatment of OFF episodes: a meta-analysis of randomized controlled trials.

BACKGROUND: Levodopa is the most commonly used first-line drug for Parkinson's disease. However, during the period of medication, the generation of motor fluctuations affects the life quality of patients. CVT-301, as an inhaled levodopa for the treatment of OFF episodes, rose in response to this condition. METHODS: We systematically searched Medline, EMBASE, Cochrane Library, and Clinicaltrials.gov for relevant randomized controlled trials, from the earliest available date to February 12, 2022, to evaluate the efficacy of high and low dose of inhaled levodopa in patients with Parkinson's disease. RESULTS: A total of six multicenter, randomized controlled trials with 1166 patients were included. Compared with placebo, CVT-301 has a statistically significant effect on the treatment of Parkinson's patients with OFF episodes of medication interval. The UPDRS Part III score decreased more significantly in the high-dose group 30 minutes after administration than the low-dose group (WMD = - 4.51; 95% CI, - 7.34 to - 1.68; p = 0.002). More patients in the high-dose group achieved and maintained an on state up to 60 min after receiving study medication (RR = 1.17; 95% CI, 1.08 to 1.27; p < 0.001). And more patients were proved with improved PGIC scores in the high-dose group (RR = 1.13; 95% CI, 1.05 to 1.21; p = 0.001). CONCLUSIONS: High doses CVT-301 can improve the motor function of the patient to some extent. There seems no risk of increasing adverse reactions.