Glucosamine occurs naturally in all human tissues. It stimulates the synthesis of glycosaminoglycan, proteoglycan and hyaluronic acid, although the precise mechanism of action remains to be established. Formulated as glucosamine sulphate (Dona) and various others), glucosamine has been evaluated for its efficacy in relieving the symptoms of osteoarthritis and its disease-modifying potential. In two large randomised, double-blind, multicentre studies in patients with osteoarthritis, oral or intramuscular glucosamine for 4-6 weeks was associated with a greater decrease in symptom severity (as assessed by the Lequesne index) than placebo. In addition, there was a greater proportion of responders (defined as patients with a >or=3-point reduction in the Lequesne index, along with a positive overall assessment by the investigator) at the end of the treatment period with glucosamine than with placebo. In two large 4-week trials, oral glucosamine produced similar improvements to ibuprofen in the Lequesne index in one study and in articular pain scores in the other study. In a smaller 8-week comparative trial, oral glucosamine therapy achieved a significantly greater improvement in articular pain score than ibuprofen, and the investigators rated treatment efficacy as 'good' in a significantly greater proportion of glucosamine than ibuprofen recipients. In comparison with piroxicam, glucosamine significantly improved arthritic symptoms after 12 weeks of therapy and remained effective 8 weeks after treatment was discontinued. Beneficial effects of long-term oral glucosamine therapy in preventing joint space narrowing and improving symptoms were shown in two 3-year placebo-controlled trials in a total of 414 patients with osteoarthritis. Statistically significant differences favouring glucosamine were noted in the per-protocol and intention-to-treat analyses for the primary endpoints for both joint structural changes and symptom modification. Glucosamine has a tolerability profile similar to that of placebo and is better tolerated than ibuprofen or piroxicam. In particular, glucosamine recipients had a markedly lower incidence of gastrointestinal disturbances than those receiving ibuprofen. Other adverse events reported in both glucosamine and ibuprofen recipients were pruritus or skin reactions, flushing and fatigue. In general, a lower incidence of withdrawal from clinical trials was reported for glucosamine recipients than either ibuprofen or piroxicam recipients.
In short-term clinical trials, glucosamine provided effective symptomatic relief for patients with osteoarthritis of the knee. In addition, glucosamine has shown promising results in modifying the progression of arthritis over a 3-year period. Glucosamine may therefore prove to be a useful treatment option for osteoarthritis.