What is osteoarthritis?
More than 20 million adults in the United States live with osteoarthritis--the most common type of arthritis. Osteoarthritis, also called degenerative joint disease, is caused by the breakdown of cartilage, which is the connective tissue that cushions the ends of bones within the joint. Osteoarthritis is characterized by pain, joint damage, and limited motion. The disease generally occurs late in life, and most commonly affects the hands and large weight-bearing joints, such as the knees. Age, female gender, and obesity are risk factors for this condition.
What are glucosamine and chondroitin sulfate?
Glucosamine and chondroitin sulfate are natural substances found in and around the cells of cartilage. Glucosamine is an amino sugar that the body produces and distributes in cartilage and other connective tissue, and chondroitin sulfate is a complex carbohydrate that helps cartilage retain water. In the United States, glucosamine and chondroitin sulfate are sold as dietary supplements, which are regulated as foods rather than drugs.
What is celecoxib?
Celecoxib (brand name Celebrex) is a type of nonsteroidal anti-inflammatory drug (NSAID), called a COX-2 inhibitor. Like traditional NSAIDs, celecoxib blocks the COX-2 enzyme in the body that stimulates inflammation. Unlike traditional NSAIDs, however, celecoxib does not block the action of COX-1 enzyme, which is known to protect the stomach lining. As a result, celecoxib reduces joint pain and inflammation with reduced risk of gastrointestinal ulceration and bleeding. Recent reports have linked possible cardiovascular side effects to COX-2 inhibitors. Although GAIT was not designed to study the safety of celecoxib, participants were monitored for adverse events and no increase in such side effects was observed.
What doses were used for the various treatments?
The doses used in GAIT were based on the doses seen in the prevailing scientific literature.
- Glucosaminen alone: 1500 mg daily given as 500 mg three times a day
- Chondroitin sulfate alone: 1200 mg daily given as 400 mg three times a day
- Glucosamine plus chondroitin sulfate combined: same doses-1500 mg and 1200 mg daily
- Celecoxib: 200 mg daily
- Acetaminophen: participants were allowed to take up to 4000 mg (500 mg tablets) per day to control pain, except for the 24 hours before pain was assessed.
Who provided the source materials for making the glucosamine and chondroitin sulfate products used in GAIT?
Glucosamine was donated in part by Ferro Pfanstiehl Laboratories, Inc., Waukegan, IL, through Wilke Resources. Chondroitin sulfate was donated by Bioiberica, S.A., Barcelona, Spain. The study agents were manufactured by Albuquerque Veterans Affairs (VA) Cooperative Studies Program Clinical Research Pharmacy.
Where did the other study products come from?
Acetaminophen was donated by McNeil Consumer and Specialty Pharmaceuticals, Fort Washington, PA.Celecoxib was purchased from Pfizer.
What did GAIT cost?
The primary GAIT study cost just over $12.5 million.
Consumer Information and Next Steps
Should people with osteoarthritis use glucosamine and chondroitin sulfate?
People with osteoarthritis should work with their health care provider to develop a comprehensive plan for managing their arthritis pain: eat right, exercise, lose excess weight, and use proven pain medications. If people have moderate-to-severe pain, they should talk with their health care provider about whether glucosamine plus chondroitin sulfate is an appropriate treatment option.
Can U.S. consumers get the glucosamine and chondroitin sulfate products used in GAIT?
Identical products may not be commercially available. GAIT was conducted under an Investigational New Drug application filed with the U.S. Food and Drug Administration (FDA). All of the products used in the study were developed for the study and subject to the FDA's pharmaceutical regulations. The products were evaluated and manufactured by the VA Cooperative Studies Program Clinical Research Pharmacy, an FDA-licensed clinical research pharmacy center. The glucosamine and chondroitin sulfate used were tested for purity, potency, quality, and consistency among batches. Products were retested for stability throughout the study.
Will the GAIT team continue to do research on glucosamine and chondroitin sulfate?
GAIT includes an ancillary study, which is still ongoing, that will assess whether glucosamine and chondroitin sulfate can reduce or halt the progression of knee osteoarthritis following additional treatment. About one-half of the participants enrolled in GAIT will be treated for an additional 18 months. As in the primary study, participants will not know to which treatment group they belong. Researchers will compare x-rays taken at the beginning of the study and after 1 and 2 years of treatment to identify changes in the knee joints as a result of treatment. Results are expected in about a year.