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Glucosamine

By Melissa G. Marko, PhD, Ara DerMarderosian, PhD

Glucosamine is a precursor of multiple cartilage constituents. It is extracted from chitin (in shells of crabs, oysters, and shrimp) and is taken in tablet or capsule form, usually as glucosamine sulfate, but sometimes as glucosamine hydrochloride. Efforts are being made to find alternative biorenewable sources including metabolically engineered fungi and E. coli (1). Glucosamine is often taken with chondroitin sulfate.

Claims

Glucosamine is claimed to relieve pain due to osteoarthritis, possibly with both analgesic and disease-modifying effects. Mechanism is unknown. Mechanism for glucosamine sulfate may be related to improved glycosaminoglycan synthesis as a result of the sulfate moiety. Dosage of glucosamine in all its forms is 500 mg po tid.

Evidence

Evidence supports use of glucosamine sulfate from Rotta Research Laboratorium for treatment of mild-to-moderate osteoarthritis of the knee when given for at least 6 mo (2-3). Other formulations still need to be rigorously evaluated. The role of glucosamine sulfate in the treatment of more severe knee osteoarthritis and osteoarthritis in other locations is less well-defined. The Glucosamine/Chondroitin Arthritis Intervention Trial (GAIT), a randomized, double-blinded, placebo-controlled, multicenter clinical trial of 1583 patients with symptomatic osteoarthritis of the knee reported that, alone and in combination with chondroitin sulfate (400 mg tid), glucosamine hydrochloride (500 mg tid) did not reduce pain effectively in the all-patient group. However, an exploratory analysis found pain relief with combination therapy in a subgroup of patients with moderate-to-severe knee pain (4).

A recent review of randomized control trials evaluating the effect of glucosamine on chronic low back pain concluded that data were insufficient to demonstrate or exclude benefits of glucosamine (5).

Adverse effects

Allergy (in patients who have shellfish allergy and take forms extracted from shellfish), dyspepsia, fatigue, insomnia, headache, photosensitivity, and nail changes may occur.Patients with chronic liver disease should also avoid glucosamine if possible, because of potential hepatotoxicity when taking glucosamine with or without chondroitin (6).

Drug interactions

No definitive interactions are known.

Glucosamine references

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