Switching dopamine agonists in advanced Parkinson's disease - Is rapid titration preferable to slow?

Background: New dopamine agonists are available, but no study has examined safe and effective ways to switch from one agonist to another. Objective: T o compare rapid- versus slow-titration schedules for starting a new dopamin e agonist in patients already on chronic agonist therapy for Parkinson's di sease. Methods: Sixteen patients on stable carbidopa/levodopa and st dopami ne agonist (bromocriptine or pergolide) switched to pramipexole using a con version calculation of 1:1 for pergolide dose and 10:1 for bromocriptine do se. Patients were randomized to two titration schedules-either slow titrati on, following the package insert and taking up to 8 weeks to reach their eq uivalent dosage (8 patients), or rapid titration, receiving the full conver ted dose the day after stopping the former agonist (8 patients) with subseq uent weekly dose adjustments. Using a blinded observer, the primary outcome variable was the time required to a Unified Parkinson's Disease Rating Sca le (UPDRS) motor score superior to baseline without increased adverse effec ts. Results: Both groups showed equivalent and statistically significant im provement after switching to the new agonist. The mean time to reach a UPDR S score that was superior to baseline without increased adverse effects was significantly shorter in the rapid-titration group (mean 2.1 weeks versus 5.3 weeks). Furthermore, with slow titration two patients experienced enhan ced parkinsonian serious adverse effects requiring hospitalization (two fal ls with fractures). Conclusion: The switchover from one agonist to another can be safely and successfully accomplished with a rapid titration based on an equivalency dose calculation.