Dosing Patterns during Conversion to IPX066, Extended-Release Carbidopa-Levodopa (ER CD-LD), in Parkinson's Disease with Motor Fluctuations

Background. IPX066 is an extended-release (ER) oral formulation of carbidopa-levodopa (CD-LD). Following an initial peak at about one hour, plasma LD concentrations are maintained for about 4-5 hours. Objective. To present dosing factors that may affect the successful conversion to ER CD-LD from other LD formulations. Methods. Two-phase 3 studies of ER CD-LD vs. immediate release (IR) CD-LD (ADVANCE-PD) and vs. CD-LD entacapone (CLE; ASCEND-PD) in subjects with advanced PD included a 6-week, open-label conversion to ER CD-LD prior to treatment randomization. The "converted" daily LD dose ratio and dose frequency for ER CD-LD were compared to the prior LD treatment regimens at study entry. Results. The average daily LD dose ratio at the end of dose conversion to ER CD LD was approximately 2.1 for IR CD-LD and 2.8 for CLE. The final dose ratios tended to be slightly higher for participants taking lower LD doses at study entry but independent of dose frequency. ER CD-LD dose frequency increased with increasing LD dose and dose frequency at study entry. Participants on higher baseline LD doses >= 800 mg and dose frequencies >= 6 tended to have higher rates of discontinuation during conversion to F;I:( CD-I,D. Conclusions. Converting participants from other LD formulations to ER CD-LD is based on their current LD regimen. For the most common daily doses (<= 1250 mg) and dose frequencies (<7) of ID, final mean dose ratios were within tight ranges of 2.1 to 2.4 for IR CD-LD (ADVANCE-PD) and 2.4 to 2.8 for CLE (ASCEND-PD) and were generally independent of the LD dosing frequency at study entry. These trials are registered with NCT00974974, NCT01130493.