DrMKZ

• e.g. Bromocriptine, ropinirole, cabergoline, apomorphine
• ergot-derived dopamine receptor agonists (bromocriptine, cabergoline, pergolide*) have been associated with pulmonary, retroperitoneal and cardiac fibrosis. The Committee on Safety of Medicines advice that an echocardiogram, ESR, creatinine and chest x-ray should be obtained prior to treatment and patients should be closely monitored
• patients should be warned about the potential for dopamine receptor agonists to cause impulse control disorders and excessive daytime somnolence
• nasal congestion and postural hypotension are also seen in some patients

Levodopa

• usually combined with a decarboxylase inhibitor (e.g. Carbidopa or benserazide) to prevent peripheral metabolism of levodopa to dopamine
• reduced effectiveness with time (usually by 2 years)
• unwanted effects: dyskinesia (involuntary writhing movements), ‘on-off’ effect, dry mouth, anorexia, palpitations, postural hypotension, psychosis
• no use in neuroleptic induced parkinsonism

MAO-B (Monoamine Oxidase-B) inhibitors

• e.g. Selegiline
• inhibits the breakdown of dopamine secreted by the dopaminergic neurons

Amantadine

• mechanism is not fully understood, probably increases dopamine release and inhibits its uptake at dopaminergic synapses

COMT (Catechol-O-Methyl Transferase) inhibitors

• e.g. Entacapone
• COMT is an enzyme involved in the breakdown of dopamine, and hence may be used as an adjunct to levodopa therapy
• used in established PD

Antimuscarinics

• block cholinergic receptors
• now used more to treat drug-induced parkinsonism rather than idiopathic Parkinson’s disease
• help tremor and rigidity
• e.g. Procyclidine, benzotropine, trihexyphenidyl (benzhexol)

*pergolide was withdrawn from the US market in March 2007 due to concern regarding increased incidence of valvular dysfunction