Background and purpose: When switching between monoamine oxidase type B (MAO-B) inhibitors, a 15-day suspension period is a precautionary measure to avoid a serotonin syndrome and hypertensive crisis. However, this indication results in a major inconvenience for parkinsonian patients because of the worsening of their clinical condition. In routine clinical practice, neurologists often perform a substitution of these two drugs without solution of continuity (i.e. overnight), to avoid worsening of fluctuations and prolonged OFF periods. Therefore, a safety open label study was performed to investigate the possible risks of switching overnight from rasagiline to safinamide.

Methods: The study population included 20 advanced patients with Parkinson's disease on stable treatment with rasagiline and levodopa (alone or in combination with other anti-parkinsonian medication). The possible occurrence of serotonin syndrome and hypertension was monitored through a strict clinical observation and a 24-h Holter recording (ABPM) performed twice, whilst subjects were on rasagiline and immediately after switching to safinamide.

Results: No cases of serotonin syndrome or hypertensive crisis occurred during the study. Changes that were not significant occurred in the primary end-point: 24-h mean blood pressure (BP) had a mild +4.4% increase in the ABPM2 versus ABPM1 (P = 0.17), 24-h systolic and diastolic BP values were slightly higher at ABPM2 compared to ABPM1 (respectively +3.3%, P = 0.13; and 5.4%, P = 0.08) and 24-h systolic BP variability was unchanged between the two ABPM evaluations (from 8.6 ± 2.9 to 8.9 ± 1.8; P = 0.27).

Conclusion: The results of the present study confirm that the overnight switch from rasagiline to safinamide is safe and well tolerated by patients.