What strikes me about this report of a new formulation of L/C is that the ratio of carbidopa to levodopa, is not fixed:
- For low levodopa doses (500mg/day) the ratio is 1:5 (cf 1:4 which is nowadays the norm).
- For high doses (1000mg/day) the ratio is 1:10.
Perhaps carbidopa levels are something that we should consider?

Intecpharma write:

[1] "The AP-CD/LD doses tested were 50/250 mg for 7 days (Group 1), 50/375 mg for 7 days (Group 3), 50/375 mg for 21 days (Group 4), and 50/500 mg for 21 days (Group 6) administered BID (twice a day).

The primary end-point of the study was to evaluate the change in the Total daily OFF Time between AP-CD/LD and current optimized LD treatment. Total OFF Time was decreased, with the AP-CD/LD, by 44% and 45% in groups 4 and 6 respectively.

The reduction in total OFF Time was achieved without increasing the ON Time with Troublesome (TS) Dyskinesia in group 4 and with decreasing Total ON Time with Troublesome Dyskinesia in group 6, resulting in an increase of Total Good On Time of 2.1h and 2.7h, respectively, in comparison to current optimized LD treatment."

[2] "The results demonstrated that plasma concentrations of carbidopa and levodopa were similar, with no statistically significant differences in all PK parameters measured, when AP-CDLD was taken with various food compositions. This suggests that the treatment with AP-CDLD, intended to be taken b.i.d (two times a day) or t.i.d (three times a day) with food, is independent of the food content."

References:

[1] AP – CD/LD - IntecPharma

[2] Topline Results of a Food Effect, Pharmacokinetic Study of AP-CDLD 5/5mg for the Treatment of Parkinson's Disease Symptoms - IntecPharma

John