Selegiline in the treatment of Parkinson's disease--long term experience.

L-deprenyl (selegiline) has been reported as a safe effective adjunctive agent to levodopa in the control of Parkinson's symptoms, as well as a means of preventing the progressive nature of the disease process. In an ongoing study, now in its 12th year, L-deprenyl has been administered 1. as monotherapy or 2. in combination with levodopa, to previously untreated patients in the early phases of the disease; 3. added to an existing regimen of levodopa when optimal therapeutic results are not being obtained. This report reviews our experience in each of these three treatment categories. Results obtained to date, indicate that L-deprenyl administered alone does not prevent the occurrence of signs of Parkinson's disease. Its administration with levodopa, as initial therapy, allows for use of lower dosage and less side-effects of the latter agent. When L-deprenyl is added to sub-optimal responders to levodopa, it attenuates fluctuating responses, particularly those of the 'end-of-dose' variety.