Effect of subcutaneous apomorphine on tremor in idiopathic Parkinson's disease

Among the cardinal symptoms of Parkinson's disease (PD) rest tremor is the least responsive to dopaminergic treatment, raising the assumption that it may not be directly related to the loss of dopaminergic neurons. Apomorphine is a potent short-acting dopamine agonist that rapidly ameliorates symptoms of PD. The aim of this study was to evaluate the extent to which apomorphine can suppress tremor in patients with idiopathic PD compared to other symptoms. The study group included 18 patients with Parkinson's disease. Increasing doses of 1 mg, 2 mg, and 4 mg of subcutaneous apomorphine were used. Treatment response was assessed with the motor section of the unified Parkinson's disease rating scale (UPDRS). Tremor, rigidity and bradykinesia were scored using specific items of the UPDRS. UPDRS motor score improved from 31.5 ± 9 at baseline to 20.0 ± 6.4 after treatment. The scores for tremor, bradykinesia and rigidity improved after administration of apomorphine. The improvement in each of these scores for each individual patient was not significantly different, i.e., the magnitude of improvement was similar for all symptoms. These results indicate that subcutaneous apomorphine appears to be as effective in the treatment of tremor in Parkinson's disease as compared to the other symptoms.