The bioavailability and pharmacokinetics of glucosamine hydrochloride and chondroitin sulfate after oral and intravenous single dose administration in the horse

OBJECTIVE: The purpose of this study was to determine if glucosamine (GL) hydrochloride (FCHG49) and low molecular weight (LMW) chondroitin sulfate (CS) (TRH122) are absorbed after oral administration to horses. The bioavailability of LMWCS was evaluated by quantifying the total disaccharides found in the plasma following chondroitinase ABC digestion. METHODS: Two separate studies were conducted. In study 1, ten adult horses received the following four treatments in a randomized crossover fashion: (1) i.v. LMWCS (3 g of 8 kDa), (2) p.o. LMWCS (3 g of 8 kDa), (3) i.v. LMWCS (3 g of 16.9 kDa) and (4) p.o. LMWCS (3 g of 16.9 kDa). Each group received 9 g GL with LMWCS. In a second study, each horse (n=2) was randomly assigned to receive either i.v. administration of GL HCl (9 g) or p.o. administration of GL HCl (125 mg/kg). Blood samples were collected, assayed and pharmacokinetic parameters were determined. RESULTS: GL was absorbed after oral dosing with a mean C(max) of 10.6 (6.9) microg/ml and a mean T(max) of 2.0 (0.7) h. The extent of absorption of LMWCS after dosing with both the 8.0 and 16.9 kDa provides evidence that LMWCS is absorbed orally. C(max) and AUC were higher (p<0.05) for the 16.9 kDa material compared with 8.0 kDa. However, the 16.9 kDa bioavailability was less than 8.0 kDa, but this difference was not significant. CONCLUSIONS: This study provides the first report of the bioavailability of orally administered GL and LMWCS in the horse.