Inter- and intra-individual variation in L-dopa pharmacokinetics in the treatment of Parkinson's disease.

Parkinson's disease is a neurodegenerative, slowly progressive, age-related disorder. Numerous medications have been developed for its treatment and the prognosis of the disorder has improved greatly over recent years. However, the effects of medicines are variable among patients, and there are also daily fluctuations in the effects of medications in the same person. The factors that cause individual variations in the effects of medicines, the causes, and strategies to cope with these fluctuations are reviewed.