After oral administration, levodopa is rapidly decarboxylated in both cerebral and extracerebral tissues to form dopamine. For this reason, most of the levodopa administered does not reach the basal ganglia, and peripheral dopamine often causes side effects. That is why it is necessary to block extracerebral decarboxylation of levodopa. This is achieved by the simultaneous use of levodopa and benserazide, an inhibitor of peripheral decarboxylase. The drug is a combination of these substances in a 4: 1 ratio and therefore has, with significantly better tolerability, the same effectiveness as levodopa used in higher doses.