<prompt> In treatment of Parkinsonism, L-Dopa is combined with carbidopa mainly:To decrease the treatment durationTo decrease central side effects of L-DopaTo decrease effectiveness of L-DopaTo increase crossing of L-Dopa through BBB  <response>: 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 