Effect of glucosamine hydrochloride in the treatment of pain of osteoarthritis of the knee

Objective. Glucosamine products have been used extensively for the manageme nt of pain in osteoarthritis (OA). We investigated the efficacy of the hydr ochloride salt of glucosamine on pain and disability in knee OA. Methods. At Week -2, subjects were examined, randomized, and instructed to take only prescribed acetaminophen for pain. At Week 0 patients were examin ed, prescribed acetaminophen, and either placebo or glucosamine hydrochlori de (glucosamine). At Week 4 the prescriptions for acetaminophen and placebo or glucosamine were renewed. At Weeks 4 and 8, patients returned diaries a nd unused medications, and were examined. The WOMAC questionnaire was admin istered at Weeks -2, 0, and 8. After completing the randomized 8 week trial , subjects were offered known glucosamine hydrochloride capsules in an 8 we ek open label trial, with followup telephone survey after the 8 week open l abel trial. Results. The primary endpoint (statistically significant difference in WOMA C pain score between Week 0 and Week 8) was not met. However, positive tren ds were noted for the glucosamine group in 23 of 24 WOMAC questions. A sign ificant difference was noted from Week 5 through Week 8 in the knee examina tion (p = 0.026) and in the response to a daily diary pain question (p = 0. 018). However, responding to the question, "Are you better than at the star t of the trial?", 40% of placebo and only 49% of glucosamine subjects answe red in the affirmative (p = 0.58). At the end of the randomized trial, 34% of placebo and 47% of glucosamine subjects believed that they had been give n glucosamine. After the end of the 8 week open label trial, 77% of the sub jects were still taking glucosamine, although now obliged to pay for commer cially available products. Conclusion. There was no significant difference in pain reduction between t he glucosamine hydrochloride and placebo groups as measured by WOMAC. Howev er, the secondary endpoints of cumulative pain reduction as measured by dai ly diary and knee examination were favorable, suggesting that glucosamine h ydrochloride benefits some patients with knee OA.