Antiparkinsonian Drugs

Parkinson’s disease is a degenerative disease of the nervous system.

Sign & symptom:
Involuntary tremulous movement (rigidity)
Pill-rolling motion of hands

Dopamine does not cross Blood Brain Barrier. Therefore, we use levodopa which is a dopamine precursor and levodopa can pass BBB. Levodopa is metabolized to dopamine by dopa-decarboxylase enzyme. In order to prevent peripheral side effect from increasing level of dopamine, we use carbidopa. Carbidopa inhibits peripheral decarboxylation of levodopa and carbidopa cannot pass BBB. Hence, level of levodopa in blood stream will increase and absorb through BBB. The combination of levodopa and carbidopa is available in tablet known as Sinemet.

Pramipexole or Mirapex is a selective dopamine receptor agonist (D2).

Ropinirole or Requip is also selective dopamine agonist (D2).