Carbidopa is a peripheral dopa-decarboxylase inhibitor that results in significant pharmacological activity only when given in combination with levodopa. Carbidoba inhibits the peripheral decarboxylation of levodopa to dopamine preventing its breakdown before reaching the brain and so increasing its effectiveness. When used with levodopa it allows for a lower dosage of levodopa to be used, a faster response time and a mitigation of adverse reactions. Marketed individual under the name Atamet, caribidopa is also available as a combination drug with levodopa under the brand name Sinemet.
Parkinson’s disease is thought to be strong linked with low levels of dopamine in the key areas of the brain. When levodopa is taken orally, it crosses through this ‘blood-brain barrier’ and then converted into dopamine. The resulting effect is an increase in brain dopamine levels that is thought to improve nerve conduction and mitigate movement disorders in Parkinson’s disease.
There is also some evidence to suggest that carbidopa when used in conjunction with 5-HTP may be useful in the treatment of myoclonus, a neuromuscular disorder.