In treatment of Parkinsonism, L-Dopa is combined with carbidopa mainly:
Administered along with levodopa, they increase its W2 ir. :periphery and make more of it available to cross blood-brain barrier to reach its site of action REF: KD TRIPATHI ESSENTIALS OF MEDICAL PHARMACOLOGY
To decrease the treatment duration
To decrease central side effects of L-Dopa
To decrease effectiveness of L-Dopa
To increase crossing of L-Dopa through BBB
Central Nervous system