The pharmacokinetic evaluation of selegiline ODT for the treatment of Parkinson's disease.

Parkinson's disease affects a growing number of people. Its major treatment, levodopa therapy, however suffers from response fluctuations in the advanced phase of the disease. Adjunctive therapies have thus gained significant importance. The selective monoamine oxidase B inhibitor, selegiline , is widely used in the treatment of Parkinson's disease. However, selegiline's pharmacokinetics has so far been unfavorable due to its extensive first-pass metabolism to its amphetamine metabolites. A new formulation, an orally disintegrating tablet (ODT), has recently been introduced to overcome these pharmacokinetic problems by avoiding its presystemic metabolism. The authors summarize the pharmacokinetic and clinical efficacy data of selegiline ODT and compare them with the more conventional oral selegiline. This evaluation also presents and compares the drug's safety data. Selegiline ODT shows a clear pharmacokinetic advantage over the conventional form. It is characterized by improved bioavailability allowing dose reduction and a lower exposure to amphetamine metabolites. This pharmacokinetic improvement, however, is not accompanied with significant clinical advantage, since its efficacy and safety profile are comparable to those of the conventional formulation. This suggests that the metabolites do not participate significantly in the therapeutic or toxic effects of selegiline. On the basis of the available data, the only well-justified advantage of the ODT formulation is its convenient use in parkinsonian patients who have difficulties in swallowing the regular formulation.