Quality of glucosamine products: Is it a potential reason for inconsistent clinical outcomes in osteoarthritis?

Background: Clinical studies have reported inconsistent outcomes of glucosamine therapy in osteoarthritis patients. One possible reason could be the use of glucosamine products of varying quality. Hence, this study aimed to assess the quality of glucosamine products marketed in Australia and India. This is the first study to investigate both the content and dissolution profiles of glucosamine products.

Methods: The content and dissolution analysis of Australian (n=25 brands) and Indian (n=21 brands) glucosamine products was performed according to the criteria specified in the United States Pharmacopoeia (USP). Results: The quality analysis revealed that 16 and 18% of Australian brands, as well as 24 and 19% of Indian brands, did not fulfil the USP content and dissolution criteria, respectively. In approximately half of these cases, the glucosamine content was only slightly below (<3%) that specified by the USP and dissolution was achieved within 15 min after the duration specified by the USP.

Conclusions: The majority of the brands did meet both the content and dissolution analysis criteria of the USP. The extent of deviation from the specified criteria for the other brands was probably insufficient to account for the significant variability in clinical effects. Hence, the study proposed that inter-patient pharmacokinetic variations in glucosamine could be another potential reason for inconsistent therapeutic effects.