Glucosamine

Glucosamine is an endogenous substance, a normal constituent of the polysaccharide chains of cartilage matrix and synovial fluid glucosaminoglycans. In vitro and in vivo studies have shown glucosamine stimulates the synthesis of physiological glycosaminoglycans and proteoglycans by chondrocytes and of hyaluronic acid by synoviocytes.

The mechanism of action of glucosamine is unknown.

The period to onset of response cannot be assessed.

Glucosamine is a relatively small molecule (molecular mass 179), which is easily dissolved in water and soluble in hydrophilic organic solvents.

The available information on the pharmacokinetics of glucosamine is limited. The absolute bioavailability is unknown. The distribution volume is approximately 5 litres and the half-life after intravenous administration is approximately 2 hours. Approximately 38% of an intravenous dose is excreted unchanged in the urine.

The ADME (absorption, distribution, metabolism and excretion) profile for glucosamine sulphate in man has not been completely elucidated.

D-glucosamine has low acute toxicity.

Animal experimental data relating to toxicity during repeated administration, reproduction toxicity or carcinogenicity is lacking for glucosamine.

Glucosamine is not mutagenic. Equivocal results concerning the clastogenic effects of glucosamine have been observed in vivo. However, these findings are not deemed clinical relevant for human safety assessment considering that glucosamine is an endogenous substance.

Results from in vitro or in vivo studies in animals have shown that glucosamine reduces insulin secretion and induces insulin resistance, probably via glucokinase inhibition in the beta cells. The clinical relevance is unknown.