A review of glucosamine for knee osteoarthritis: why patented crystalline glucosamine sulfate should be differentiated from other glucosamines to maximize clinical outcomes.

The European Society for Clinical and Economic Aspects of Osteoporosis and Osteoarthritis (ESCEO) treatment algorithm for knee osteoarthritis (OA) recommends symptomatic slow-acting drugs for osteoarthritis (SYSADOAs) first line for the medium to long term management of OA, due to their ability to control pain, improve function, and delay joint structural changes. Among SYSADOAs, glucosamine is probably the most widely used intervention. In the present review of glucosamine for knee OA, we have investigated whether the evidence is greater for the patented crystalline glucosamine sulfate (pCGS) preparation (Rottapharm/Meda) than for other glucosamine formulations. Glucosamine is actually widely available in many forms, as the prescription-grade pCGS preparation, generic and over-the-counter formulations of glucosamine sulfate (GS) and food supplements containing glucosamine hydrochloride (GH), which vary substantially in molecular form, pharmaceutical formulation and dose regimens. Only pCGS is given as a highly bioavailable once daily dose (1500 mg) with a proven pharmacological effect. pCGS consistently reaches the plasma levels of around 10 μM required to inhibit interleukin-1 induced expression of genes involved in the pathophysiology of joint inflammation and tissue destruction, compared with sub-therapeutic levels achieved with GH. It is evident, from careful consideration of the evidence base, that only the pCGS formulation of glucosamine reliably provides an effect size on pain that is higher than that of paracetamol and equivalent to that provided by non-steroidal anti-inflammatory drugs. In comparison, the effect size on pain of non-crystalline GS preparations and GH from randomized controlled trials is repeatedly demonstrated to be zero. In addition, there is evidence that chronic administration of pCGS has disease-modifying effects, with a reduction in the need for total joint replacement surgery lasting for at least 5 years after treatment cessation. Consequently, the pCGS preparation (Rottapharm/Meda) is the logical choice, with demonstrated medium-term control of pain and lasting impact on disease progression.