Apomorphine: a powerful ally in Parkinson's disease

Introduction. Apomorphine, a D1-D2 dopamine agonist, is the oldest drug with proven efficacy in the treatment of Parkinson's disease (PD), and the only with similar symptomatic power to levodopa. Its usefulness in the control of motor fluctuations, both as intermittent injections and in continuous subcutaneous infusion, has been demonstrated in open label and placebo controlled trials. Aim. To analyse the role of apomorphine in the varied clinical symptoms and different clinical stages of PD through a narrative review of scientific literature (1951-2020). Development. Beyond on-time increase, off-time decrease, off dystonia and quality of life improvement in advanced PD, there is evidence to support a role of apomorphine in less known clinical areas of PD, such as non motor symptoms, a lower risk of impulse control disorders, potential to ameliorate visual hallucinations, improve neuropsychiatric symptoms and dyskinesia and even axial features. Nevertheless, the optimal timing of apomorphine treatment remains controversial, and its implementation of this valuable drug in clinical practice has been historically hindered by several factors. Conclusions. Apomorphine is a unique drug in the PD treatment scenario, with a number of potential applications beyond motor fluctuations control. Acknowledging these properties, selecting the patient most likely to benefit from it and finding the right timing may be key in the symptomatic control of this complex disease.