Joint Supplement Research

The role of glucosamine and chondroitin sulfate in treatment for and prevention of osteoarthritis in animals- PDF

June 01 2000, Article # 3097

Researchers from the University of Maryland’s Department of Pharmaceutical Sciences, School of Pharmacy, recently published a report that showed some over-the-counter human products claiming to contain glucosamine and chondroitin did not have the amounts claimed on the label. In fact, deviation from label claims ranged from 0% to more than 115%.

The objective of the re- search, published in the Journal of the American Nutraceutical Association, was “to evaluate the results of analysis of actual contents of several products in the marketplace containing glucosamine and/or chondroitin sulfate and to determine if they significantly deviate from label claim.” The researchers took 14 products containing glucosamine hydrochloride or glucosamine sulfate and 11 products containing chondroitin sulfate to evaluate using one method (UV-HPLC). They also took 32 products containing only chondroitin sulfate to test with another method (titration). This analysis was “an attempt to evaluate whether different suppliers of glucosamine or chondroitin sulfate use different grades of material.”

What the researchers found was that some products didn’t contain any of the labeled materials, and some contained more than was labeled. “Our results suggest that there is a significant deviation between the content of the active ingredients (glucosamine or chondroitin sulfate) and what is stated by the manufacturers on the label.” They also discovered that products with a retail price “of less than or equal to one dollar per 1,200 mg of chondroitin sulfate were found to be seriously deficient in meeting label claim (less than 10% of label claim).”

The study also examined the intestinal transport (an indirect method to evaluate intestinal absorption) of several marketed sources of chondroitin sulfate to determine if these products could be absorbed in the GI tract. The researchers assessed permeability of various marketed sources of raw materials of chondroitin sulfate across Caco-2 cell monolayers.

The research report noted that the permeability of the different molecular weight chondroitin sulfates was “found to be significantly different, with the permeability coefficient increasing with decreasing molecular weight. This suggests that molecular weight of chondroitin sulfate could be a possible predictor of permeability.” (In other words, low molecular weight chondroitin sulfate is better than high molecular weight chondroitin sulfate. For you scientists out there, they reported “significant” permeability differences with the coefficient increasing with decreasing molecular weight of 16.9, 8.0, and 4.0 x 103 Daltons.)

Problem is, if a consumer can’t trust what is in a product by the label claim for human products, what can a horse owner do? The same as is recommended to humans by the Arthritis Foundation: 1) consult with your physician (veterinarian); 2) health care professionals (vets) should become knowledgeable about these products; 3) consumers should not purchase through the mail or Internet unless they know the vendor; and 4) consumers should buy from companies that use USP material (neither chondroitin sulfate nor glucosamine have a monograph yet). (United States Pharmacopeia, or USP, is the book that contains standards and regulations for human and vet drugs.)

The group also said that “the implications of these results are significant and support the need for regulatory intervention of dietary supplements.”


Byron CR, Benson BM, Stewart AA, Pondenis HC.
Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois, Urbana-Champaign, IL 61801, USA.

To evaluate the effects of methylprednisolone acetate (MPA) on proteoglycan production by equine chondrocytes and to investigate whether glucosamine hydrochloride modulates these effects at clinically relevant concentrations. SAMPLE POPULATION:
Articular cartilage with normal gross appearance from metacarpophalangeal and metatarsophalangeal joints of 8 horses (1 to 10 years of age).
PROCEDURES: In vitro chondrocyte pellets were pretreated with glucosamine (0, 1, 10, and 100 microg/mL) for 48 hours and exposed to MPA (0, 0.05, and 0.5 mg/mL) for 24 hours. Pellets and media were assayed for proteoglycan production (Alcian blue precipitation) and proteoglycan content (dimethylmethylene blue assay), and pellets were assayed for DNA content. RESULTS:
Methylprednisolone decreased production of proteoglycan by equine chondrocytes at both concentrations studied. Glucosamine protected proteoglycan production at all 3 concentrations studied. CONCLUSIONS AND CLINICAL RELEVANCE:
Methylprednisolone, under noninflammatory conditions present in this study, decreased production of proteoglycan by equine chondrocytes. Glucosamine had a protective effect against inhibition of proteoglycan production at all 3 concentrations studied. This suggested that glucosamine may be useful as an adjunct treatment when an intra-articular injection of a corticosteroid is indicated and that it may be efficacious at concentrations relevant to clinical use.

Research Ongoing

by: Stacey Oke, DVM, MSc
March 26 2008, Article # 11549

Canadian researchers recently compared the pharmacologic properties of two different forms of glucosamine–hydrochloride and sulphate. They measured significantly higher levels of glucosamine in synovial fluid samples from horses receiving the oral glucosamine sulphate formulation as compared to synovial fluid levels in horses receiving oral glucosamine hydrochloride.

Glucosamine is a common ingredient in oral joint health supplements that are widely administered to horses with osteoarthritis. Glucosamine is available in a number of different forms including hydrochloride, sulphate, and N-acetyl-D-glucosamine. To date, there is conflicting evidence surrounding the use of glucosamine for the management of osteoarthritis, regardless of species.

“It has been proposed that the type of glucosamine used may impact efficacy,” explained Sheila Laverty, MVB, Dipl. ACVS, professor and specialist in equine surgery in the University of Montreal’s Veterinary School. Laverty is also a member of the Canadian Arthritis Network.

A recent review article suggests that the most favorable clinical trial results of osteoarthritis in humans were associated with the use of glucosamine sulphate, which is currently available for human use by prescription only in European countries.

In the study by Laverty and colleagues, horses were administered clinically relevant doses of glucosamine hydrochloride or glucosamine sulphate (20 mg/kg) via nasogastric intubation. They administered the preparation of glucosamine sulphate reported to be beneficial in Europe. Both types of glucosamine were absorbed and were measurable in synovial fluid at one, six, and 12 hours after administration.

“Following administration, synovial levels of glucosamine were significantly higher at one and six hours post-administration of glucosamine sulphate compared to glucosamine hydrochloride,” summarized Laverty. Pure glucosamine hydrochloride was employed, but the investigators were unable to obtain commercially available pure glucosamine sulphate for their study.

Laverty pointed out that there were substances to improve palatability included with the glucosamine sulphate preparation they studied. She suggested that these substances might have enhanced the absorption of the glucosamine molecule. In addition, it is not clear whether these differences in synovial fluid levels will have a real, clinical impact on horses with osteoarthritis. Further research is required.

The study, “Comparison of pharmacokinetics of glucosamine and synovial fluid levels following administration of glucosamine sulfate or glucosamine hydrochloride,” will be published in an upcoming edition of the journal Osteoarthritis and Cartilage.