Monitoring the Level of 14C-Labelled Selegiline Following Oral Administration.

BACKGROUND: Selegiline [(-)-deprenyl] is widely used for the treatment of Parkinson's disease in humans. OBJECTIVE: Time-dependence of tissue distribution of selegiline following per os administration to rats. METHOD: Oral administration of radiolabeled selegiline to rats resulted in a pattern of tissue distribution similar to that following intraperitoneal injection. Analyses were done using both reversed-phase HPLC and also by counting radioactivity in various body compartments of rats. RESULTS: As a consequence of oral administration of 30 mg/kg of selegiline, its level in the stomach was extremely high (179.57 µg/g tissue through 54.67 µg/g at 15 min to 120 min), that is one magnitude higher than that in the serum level. High selegiline concentrations were also detected in the lacrimal glands (7.45 µg/g), kidneys (6.87 µg/g), livers (6.01 µg/g) and lungs (3.47 µg/g) after 30 minutes of application, which were higher than after intraperitoneal injections. CONCLUSION: The relatively high tissue levels remained for 120 min monitoring. Selegiline levels in the brain (1.69 µg/g) and in the testes (1.88 µg/g) were also considerably higher than following intraperitoneal administration during the entire period of observation (15 to 120 min).

Distribution of N-methyl-(14)C-labeled selegiline in the rat.

Tissue distribution of selegiline including N-methyl-(14)C-selegiline was studied with three different techniques. Whole body autoradiography of labeled selegiline in rats completed the former results obtained in mice. Counting radioactivity by liquid scintillation method in various body compartments gave an in-depth numerical estimation of distribution, while RP-HPLC determination of selegiline determined the fate of intact, non-metabolized parent compound. Whole body autoradiography following 15 and 60 min of intraperitoneal application of N-methyl-(14)C-selegiline verified definite and time-dependent blood-brain penetration of selegiline. Quantitative determination of tissue concentrations by liquid scintillation and RP-HPLC methods following 5, 15, 60 and 180 min of intraperitoneal administration of selegiline unanimously verified both blood-brain and blood-testis penetration of the compound through the barrier.