Review Question - QID 105026

Side effects of levodopa/carbidopa can include hallucinations, dizziness, headache, and agitation (which may appear immediately). After several years of therapy, involuntary movement may occur.

Firstline treatment of Parkinson's disease is levodopa/carbidopa. L-dopa increases the level of dopamine in the brain and crosses the blood-brain barrier where it is converted by dopa decarboxylase to dopamine. Carbidopa acts as a peripheral decarboxylase inhibitor, thus increasing the amount of L-dopa that reaches the brain and limiting peripheral side effects. It is best for treating bradykinesia. With long term use, however, it can cause dyskinesia following administration and akinesia between dosages. Other treatments include bromocriptine (a direct dopamine agonist), anticholinergic drugs for tremor, and selegiline, which inhibits breakdown of dopamine in the brain. Amantadine is effective in mild disease.

Rao et al. discuss the diagnosis and treatment of Parkinson's disease. Levodopa is the primary treatment for Parkinson's disease. However, its long-term use is limited by motor complications and drug-induced dyskinesia. Dopamine agonists are options for initial treatment and have been shown to delay the onset of motor complications. However, dopamine agonists are inferior to levodopa in controlling motor symptoms.

Olanow and Schapira discuss therapeutic prospects for Parkinson disease. Dopaminergic therapies such as levodopa have provided benefit for millions of patients with Parkinson's disease and revolutionized the treatment of this disorder. However, patients continue to experience disability despite the best of modern treatment. Dopaminergic and surgical therapies are associated with potentially serious side effects. Major therapeutic unmet needs include a dopaminergic therapy that is not associated with serious side effects, a therapy that addresses the non-motor and non-dopaminergic features of the disease, and a disease-modifying therapy that slows or stops disease progression.

Illustration A depicts the classic shuffling gait observed in Parkinson's disease. Illustration B shows the degeneration of the substantia nigra seen in pathological specimens of patients with Parkinson's disease.

Incorrect Answers:
Answer 1: Agranulocytosis is a potential side effect of carbamazepine, an epilepsy drug.
Answer 2: Coronary vasospasm is a potential side effect of sumatriptan, a drug for acute migraine.
Answer 3: Lupus-like syndrome is a potential side effect of phenytoin, an anti-epileptic.
Answer 5: Stevens-Johnson syndrome is a potential side effect of lamotrigine, an anti-epileptic drug.