Apomorphine in the treatment of Parkinson's disease

Apomorphine is a potent, nonselective, direct-acting dopamine-receptor agonist. Given subcutaneously, it has a rapid onset of antiparkinsonian action qualitatively comparable to that of levodopa. Despite its long history, it was not until peripheral dopaminergic side effects could be controlled by oral domperidone that the clinical usefulness of apomorphine in Parkinson's disease began to be investigated thoroughly in the mid-1980s. Although several routes have been tried, subcutaneous administration, either as intermittent injections or continuous infusion, is so far the best and most applied in the treatment of advanced, fluctuating Parkinson's disease. Clinical trials have shown stable efficacy with markedly reduced time spent in "off" phases as well as, for infusion therapy, reduced levodopa requirements. In the most successful cases, motor fluctuations disappear and the need for oral medication is eliminated. Adverse events are usually mild and dominated by cutaneous reactions. Neuropsychiatric side effects occur, but the influence of apomorphine on these remains controversial. Controlled long-term clinical trials are highly warranted to reveal the full potentials of this treatment. Careful patient selection and follow-up, where the specialized movement disorder nurse has a crucial role, are paramount for a successful long-term outcome. Apomorphine warrants a wider application in the treatment of advanced Parkinson's disease and should be tried before more invasive interventions are considered.