Glucosamine Sulfate in Osteoarthritis: The Jury Is Still Out

Treatment in osteoarthritis has 3 goals: relief of symptoms (pain), preservation of function (daily activities in life), and delay of joint damage (cartilage and bone) (1). Millions of patients with osteoarthritis use glucosamine. However, despite more than 4 decades of use and many controlled and uncontrolled trials, the effects of glucosamine on these outcomes are still unproven (2). One possible explanation is the lack of a standard preparation. The U.S. Food and Drug Administration classifies glucosamine as a dietary supplement and does not require standardization of its content and purity. An Italian company, Rottapharm, produces a standardized preparation that is the only one approved as a prescription drug for osteoarthritis (in the European Union).

The Cochrane Collaboration recently updated its review of glucosamine therapy in osteoarthritis; the body of evidence included 20 studies with 2570 patients (3). Eighty percent of the evaluated studies dealt exclusively with the effects of glucosamine on knee osteoarthritis; only 10% evaluated the effects on osteoarthritis at multiple sites (hip, knee, and others), and the investigators did not analyze glucosamine effects at different sites of osteoarthritis. The Cochrane authors analyzed trials of the Rottapharm preparation separately and found that it reduced joint pain and increased function more than placebo. Pooled results from studies of non-Rottapharm preparations did not demonstrate that glucosamine alleviated pain or improved physical function. The same was true of studies that adequately concealed the order of random assignment. Concerns about the body of evidence have focused on inadequate allocation concealment and the potential for industry bias in the studies of the Rottapharm product, but the specific properties of that preparation have been stressed as well (4, 5). The reported effect sizes are small; …