In a double-blind study, researchers investigated the efficacy of a medicine that delivered both glucosamine and chondroitin sulfate. The 164 participants all had osteoarthritis and moderate to severe knee pain.
Half the participants were randomly assigned to receive the experimental drug (1,200 mg chondroitin sulfate plus 1,500 mg glucosamine sulfate) and the other half received a placebo. Each participant reported their global pain levels and used a questionnaire to report on osteoarthritis-related pain.
The study was intended to consist of two steps: a six-month initial phase and a second phase that would be initiated if initial patient response was strong. Unexpectedly, the results were so strongly skewed toward the placebo that the study was discontinued.
“Intriguingly,” the authors report, the combination pill was inferior to placebo in reduction of joint pain on a visual analog scale for the modified intention-to-treat population (19% vs. 33%; P<0.03), but there was no difference between groups in the per-protocol cohort. Among patients who completed the entire six-month trial, 13.6% who took the drug reported reduced pain levels compared to 20.1% of those who took the placebo (P=0.07).
Nor were there any differences in secondary outcomes (i.e., total score on WOMAC [Western Ontario and McMaster Universities Arthritis Index]), and pain and function subscales, the proportion of OMERACT-OARSI (Outcome Measures in Rheumatology-Osteoarthritis Research Society International) responders, and use of rescue medication.
The study is the latest in a line of clinical trials that show little to no benefit for glucosamine or chondroitin in the treatment of osteoarthritis or knee pain.
Jorge Roman-Blas of Madrid’s Fundacion Jimenez Diaz Hospital, the study’s first author, tells Reuters Health via email that adverse effects, such as diarrhea and abdominal pain, were more common in those who took the glucosamine-chondroitin sulfate drug.
He acknowledged that the small sample size and the fact that patients were allowed to occasionally use acetaminophen as a rescue drug could have influenced the outcome.
“Maybe more strict statistical criteria could be required for (future) clinical trials based on health questionnaires,” he adds.
“This study adds to a growing body of literature which (has) failed to demonstrate that these supplements offer relief from osteoarthritis,” Kate Lapane of the University of Massachusetts Medical School tells Reuters Health via email.
In 2015, Lapane reported similar findings from a four-year follow-up analysis on glucosamine and chondroitin using data from the National Institutes of Health’s Osteoarthritis Initiative.
“These supplements can be costly and are not covered by health insurance,” notes Lapane. “Patients should consider the fact that they have not been proven to be efficacious before spending money on glucosamine/chondroitin supplements for osteoarthritis.”
The trial, which was funded by Spanish pharmaceutical company Tedec Meiji Farma SA, was the first to evaluate the efficacy of a combination of both drugs and include a data safety monitoring board to ensure bias-free data. Tedec Meiji did not participate in the study’s design or administration.