Pharmacology: Mechanism of Action: Glucosamine is a natural substance found in chitin, mucoproteins, and mucopolysaccharides. It is involved in the manufacture of glycosaminoglycan, which forms cartilage tissue in the body, glucosamine is also present in tendons and ligaments. Glucosamine must be synthesized by the body but the ability to do this decline with age. Glucosamine and its salts have therefore been advocated in the treatment of rheumatic disorders including osteoarthritis. Glucosamine also acts to improve the viscosity of synovial fluid by increasing synovial fluid production, thereby providing lubricant activity. Chondroitin sulphate, as a vital component of aggrecan, helps to maintain the structural integrity of cartilage tissue. Loss of chondroitin sulphate from joint cartilage leads to loss of cartilage resilience and shock-absorbing properties. Orally administered chondroitin sulphate leads to increase in hyaluronic acid production and viscosity of synovial fluid. Chondroitin sulphate also inhibits the enzymes involved in degradation of cartilage. Combination therapy with glucosamine and chondroitin helps to protect joint cartilage from damage (chondroprotection), reduces joint pain and improves joint function and mobility. Glucosamine and chondroitin combination is effective in all forms of degenerative joint diseases such as osteoarthritis and arthrosis, both acute and chronic, bringing relief or reduction of joint pains, improvement in joint function, and inhibition or reversal of the degenerative disease process.
Pharmacokinetics: Following oral administration, glucosamine sulphate is well absorbed from the gastrointestinal tract. The absolute bioavailability is 26% due to first-pass effect in the liver. The gastrointestinal absorption is close to 90%. Glucosamine is not protein bound, but rather incorporates into plasma protein (primarily globulins). The volume of distribution is 2.5 liters. Plasma levels of glucosamine reach a peak after 8-10 hours and then decline, exhibiting a half-life of 68 hours. The first-pass effect in the liver in which more than 70% of glucosamine is metabolized. About 10% is excreted in the urine, with about 11% found in the faeces. Part of the dose of glucosamine sulphate is eliminated as carbon dioxide via expired air. After oral administration, chondroitin sulphate is absorbed from the gastrointestinal tract and is distributed into the joint space.