Treatment of PD with levodopa was begun in 1960. It is still the most effective drug for the control of the symptoms of PD.

Mechanism of action
Because of the way it is metabolized, levodopa is almost always administered in combination with carbidopa. This combination is called Sinemet® and it avoids side effects of peripheral dopamine, i.e., nausea, vomiting, postural hypotension, sinus tachycardia and orange color of urine.

Timing of initiation
It was and still is the gold standard antiparkinsonian agent but the timing of its initiation remains somewhat controversial.7 Once it is absolutely necessary and when it is finally instituted, the lowest possible dose should be given. Higher dose may cause nausea, dizziness, insomnia, nervousness and vague mental symptoms (psychosis).

Side effects/complications
Complications due to levodopa therapy are usually directly proportional to the duration of treatment.

Most common serious adverse reactions are