Dopaminergic drugs

• e.g. levodopa, dopamine agonists, monoamine oxydase type B inhibitors, and less commonly amantadine

Main indication

• Treatment of Parkinson's - alleviates motor symptoms

Mechanism of action

• All increase dopamine concentration in the brain

Contraindications and cautions

• Dopamine agonists should be avoided in patients with a history of addiction, obsessive-compulsive disorders and impulsive personality

Adverse effects

• Dopamine agonists and levodopa are associated with nausea, daytime somnolence, and oedema (more so in dopamine agonists)
• Postural hypotension
• Impulse control disorders, including pathological gambling, hypersexuality, binge eating, compulsive spending occur much more often with dopamine agonists
• Dopamine agonists are also more commonly associated with hallucinations and should therefore not be prescribed in the elderly, especially those with cognitive impairment
• Levodopa provides the greatest symptomatic benefit, but long-term use is associated with motor complications (dyskinesia and motor fluctuations)

Long-term compliciations

• Motor fluctuations - alterations between periods of good motor symptom control (on time) and periods of reduced motor symptom control (off time)
• Non-motor fluctuations - alterations between periods of good non-motor symptom control and periods of reduced non-motor symptom control
• Dyskinesia - involuntary choreiform or dystonic movements, which occur most frequently when levodopa concentrations are at their maximum (peak-dose), less commonly can occur at the end of a dose
• Drug-induced psychosis

Administration