Apomorphine monotherapy in the treatment of refractory motor complications of Parkinson's disease: long-term follow-up study of 64 patients.

Continuous subcutaneous infusion of apomorphine is now increasingly recognized as an effective treatment for refractory off periods and peak-dose dyskinesias in Parkinson's disease. We have reviewed our experience with apomorphine infusions, after a strategy decision in 1995 based on emerging preclinical data, to treat all patients with steady-state plasma levels of apomorphine throughout the waking day, minimizing additional pulsatile stimulation either by oral dopaminergic medication or bolus parenteral injections of apomorphine. Sixty-four patients have been treated with apomorphine pumps and 45 of these successfully converted to monotherapy, managing to discontinue all other forms of dopaminergic stimulation during the daytime treatment period with apomorphine. Patients were followed up for a mean of 33.8 months (range, 4-108 months) and clinical data analyzed retrospectively. The mean maintenance dose of apomorphine was 98 mg per 24 hours (monotherapy group: 103 mg/24 hours; polytherapy group: 93 mg/24 hours), which did not significantly increase at final follow-up. There was a mean maximum dyskinesia reduction of 64% (S.D. = 20) in the monotherapy group, compared to 30% (S.D. = 33) in those continuing on polytherapy (P < 0.001), despite a maintained increase in on time (monotherapy group: 55%, P < 0.005; polytherapy group: 50%, P = 0.05). Fifteen patients failed to successfully convert to monotherapy but benefited nonetheless, and only 3 failed apomorphine infusional therapy altogether. Reasons for failure were mixed, including difficulty with compliance and adverse effects such as daytime somnolence, skin complications, and painful dystonias. There was a significantly higher success rate in patients able to manage the treatment either independently or with the help of their caregiver. These results confirm that subcutaneous apomorphine monotherapy can reset peak-dose dyskinesia threshold in levodopa-treated patients and further reduce off-period disability after all available forms of oral medication, including long-acting dopamine agonists, have been tried.