Concomitant Medication Usage with Levodopa-Carbidopa Intestinal Gel: Results from the COSMOS Study

Background: Levodopa-carbidopa intestinal gel (LCIG) is administered directly to the small intestine of patients with advanced Parkinson's disease (APD) to help maintain stable plasma levodopa levels. Objective: The objective of this study was to investigate the effect of LCIG in reducing polypharmacy for the treatment of APD. Methods: The COmedication Study assessing Mono- and cOmbination therapy with levodopa-carbidopa inteStinal gel (COSMOS) is a large, real-world, multinational observational study investigating comedication use with LCIG. All enrolled patients had used LCIG for ≥12 months and data were collected cross-sectionally (study visit) and retrospectively. The primary endpoint was the percentage of patients using LCIG as monotherapy (without add-on PD medications) at initiation and at 3, 6, 9, and 12 months thereafter. Results: Overall, 409 patients were enrolled from 14 countries and were treated with LCIG for a mean of 35.8 ± 23.2 months. A total of 15.2% of patients initiated LCIG as monotherapy and 31.7% were receiving monotherapy at 12 months after initiation. The mean duration of LCIG monotherapy was 39.3 ± 25.6 months. Use of add-on medications decreased over time with all LCIG regimens. From LCIG initiation to the patient visit, mean off time decreased by 3.8, 4.6, and 3.9 hours/day for LCIG monotherapy, LCIG daytime monotherapy, and LCIG polytherapy groups, respectively, while duration of dyskinesia decreased by 1.7, 2.0, and 1.9 hours/day, respectively. Adverse events likely related to study treatment occurred in 112 patients (27.4%) during LCIG treatment. Conclusions: LCIG is an effective long-term monotherapy option with a positive risk–benefit profile and contributes to reduced polypharmacy for patients with APD.