Pharmacokinetics of glucosamine in the dog and in man
Setnikar, I.; Giacchetti, C.; Zanolo, G.
Arzneimittel-Forschung 36(4): 729-735
1986
ISSN/ISBN: 0004-4172 PMID: 3718596 Document Number: 495
The pharmacokinetics, organ distribution, metabolism and excretion of glucosamine were studied in the dog giving uniformly labelled [14C]-glucosamine (sulfate), i.v. or orally, in single doses. Immediately after i.v. administration, the radioactivity in plasma is due to glucosamine, and freely diffuses into organs and tissues. This radioactivity disappears quickly from plasma (initial t1/2=13 min, terminal t1/2=118 min). After 30-60 min the radioactivity in plasma is no longer due to glucosamine, but is incorporated into .alpha.- and .beta.-globulins. The protein-incorporated radioactivity is found already 20-30 min after i.v. administration, reaches a peak after 8 h and then slowly disappears, with a t1/2=2.9 days. Of the administered radioactivity, more than 34% is excreted in the urine, mainly as glucosamine, and 1.7% is excreted in the feces. Radioactivity is excreted also as [14C]-CO2 in the expired air. The radioactivity, after i.v. administration, diffuses rapidly from blood into the body. Some organs show an active uptake of radioactivity, e.g. the liver and the kidney. Other tissues, such as the articular cartilage, also have an active uptake. In most other organs the radioactivity found can be explained by passive diffusion processes from plasma. After oral administration of a single dose of [14C]-glucosamine the radioactivity is quickly and almost completely absorbed from the gastrointestinal tract. The pattern of disappearance, metabolic transformation, tissue distribution and excretion of the radioactivity are consistent with those found after i.v. administration. In man unlabelled glucosamine sulfate (Dona 200-S) was given i.v. and orally and glucosamine was measured in plasma and urine with a glucosamine-specific ion-exchange chromatographic method. The results show that the bioavailability, pharmacokinetics and excretion pattern of glucosamine are consistent with those found in the dog with radiolabelled glucosamine, and with those reported in a previous study in the rat.
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