Faculties of Pharmacy and Medicine, University of Alberta, Edmonton, Alberta, Canada.
OBJECTIVE: To assess the content of active ingredient in over-the-counter (OTC) glucosamine sulfate (GLS) preparations. METHODS: We analyzed in a coded, blind manner 14 commercially available capsules or tablets of GLS, plus one herbal mixture as a control. We used a high performance liquid chromatography system as described. RESULTS: The amount of free base varied from 41 to 108% of the mg content stated on the label; the amount of glucosamine varied from 59 to 138% even when expressed as sulfate. CONCLUSION: If GLS is used as a therapeutic agent, it is important that the products conform to a standard in their description. The content is probably best expressed in terms of free base.