Levodopa is converted to dopamine in the brain to treat Parkinson's Disease.
Commonly combined with decarboxylation inhibitors such as benserazide (Prolopa) and carbidopa (Sinemet) to increase penetration into the blood-brain barrier
Dosing:
-multiple times daily (due to short half-life)
-best absorption is empty stomach, but may be taken with food if nausea occurs
-high protein meals may reduce absorption
-domperidone may be added to manage nausea or hypotension
-controlled-release versions can be given at bedtime
Adverse Effects:
-dizziness (hypotension)
-nausea
-hallucinations
-dyskinesia/wearing off, depending on high/low dose
-increased libido
-nightmares/insomnia
-psychosis
-neuroleptic malignant syndrome
-impulse behaviours
Drug Interactions:
-iron and protein reduce levodopa absorption
-antipsychotics may reduce levodopa action through dopamine blockade
-increased dizziness with antihypertensive medications
-isoniazid may reduce levodopa effect
-increased risk of hypertensive crisis with non-selective MAO inhibitors such as tranylcypromine and phenelzine