Single dose pharmacokinetics and bioavailability of glucosamine in the rat.

PURPOSE To study pharmacokinetics of glucosamine following various routes of administration of the hydrochloride salt to rats and locate the site of its first-pass metabolism. METHODS Rat were cannulated in the jugular vein and single intravenous, oral and intra peritoneal doses of 350 mg/kg were administered. Serial blood samples were collected and plasma glucosamine concentrations were determined using HPLC. RESULTS After intravenous administration, the apparent terminal half-life (1.09 +/- 0.98 h), apparent steady state volume of distribution (2.1 +/- 1.1 L.kg(-1)) and total body clearance (2.61 +/- 0.81 L.kg(-1.h-1)) were calculated. The peak plasma concentration, after oral administration, occurred approximately 30 min post-dose and the absolute bioavailability was 0.19. Glucosamine was completely bioavailable after intraperitoneal administration. CONCLUSION Orally administered glucosamine is rapidly absorbed, highly distributed and efficiently cleared. The gut rather than liver is mainly responsible for the first pass metabolism since reduced bioavailability is observed after oral but not intraperitoneal doses.