R-(-)-deprenyl and parkinsonism.

L-deprenyl is a potent, well tolerated and safe inhibitor agent of MAO-B. Administration in daily dosage of 10 mgs produces an almost complete inhibition of the enzyme. Clinical trials of the use of l-deprenyl in Parkinson's disease have shown the following: l-deprenyl as monotherapy in Parkinson's disease does not control its symptoms. In those on a therapeutic regimen containing levodopa and experiencing fluctuating responses, particularly the "wearing off" type, the addition of l-deprenyl results in their attenuation or control. It is not fully agreed by all investigators whether such as effect is enduring or begins to wane after two or three years, nor that other symptoms of parkinsonism are improved. One investigator has reported that the combined use of these agents has resulted in an increase in life expectancy in Parkinson's disease. They have suggested that these findings indicate that l-deprenyl may be capable of preventing degeneration of the nigro-striatal system and halting progression of the Parkinson's disease process. This has raised the issue of initiating treatment with l-deprenyl during the early phases of Parkinson's disease.