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Objectives Clinical trial data for the efficacy of glucosamine in OA are conflicting. Reportedly, Rotta-manufactured glucosamine products are more likely to be effective, and a possible explanation is greater bioavailability than other brands. Specifically, the aim was to compare the steady-state pharmacokinetics of Rotta- and non-Rotta-manufactured glucosamine products in healthy volunteers and examine the interindividual variability. Methods In a crossover design, healthy adult participants ingested 1500 mg/day of a Rotta (DONA powder sachets; imported by Mylan Health, Carole Park, QLD, Australia) and a non-Rotta (glucosamine sulphate 1500 mg one-a-day tablet; Blackmores, Warriewood, NSW, Australia) glucosamine product/brand individually for 6 days. Blood samples were collected immediately before and for 12 h after the ingestion of the last dose of each brand and analysed to determine plasma levels of glucosamine. The pharmacokinetic parameters at steady state [including the minimum (Css min) and maximum (Css max) plasma concentration of glucosamine, time to reach Css max post-dosing (Tss max) and area under the plasma concentration vs time curve (AUCss 0–12)] for each brand were calculated and statistically compared. Results Fourteen participants [mean age 35.5 years (s. d. 8.8)] were recruited (64.2% males). No significant differences were observed in the pharmacokinetic parameters between the two brands. However, for both brands, the coefficient of variation for Css min, Tss max and AUCss 0–12 exceeded 20%, indicating considerable differences in the parameters between participants. No significant association of the pharmacokinetic parameters was observed with various dosing- and participant-related variables. Conclusion Substantial interindividual differences in the absorption and elimination of glucosamine could be a cause of variable clinical outcomes in OA. Trial registration The study was registered with the Australian New Zealand Clinical Trials Registry (http://www.ANZCTR.org.au/ACTRN12618000699268p.aspx) , number ACTRN12618000699268p. [ABSTRACT FROM AUTHOR]

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. Objective: 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. Method: The content and dissolution analysis of Australian (n¼25 brands) and Indian (n¼21 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 15min 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. Highlights: • Glucosamine is widely used in osteoarthritis, despite variable outcomes in trials. • Quality analysis was performed to test Australian and Indian brands of glucosamine. • The majority fulfilled content and dissolution criteria. • The quality of products is unlikely to explain variable outcomes with glucosamine. [ABSTRACT FROM AUTHOR]