Efficacy of Intramuscular Chondroitin Sulfate and Compounded Acetyl-d-Glucosamine in a Positive Controlled Study of Equine Carpitis

Abstract

Summary

Thirty healthy lameness-free horses were subjected to the Complete Freund's Adjuvant (CFA) (Sigma, St Louis, Mo) carpitis model, which was allowed to develop for 5 days. The horses were then stratified by model-induced deficit in lameness score, carpal flexion, stride length, and carpal circumference, and they were randomly assigned to 3 groups of 10 horses. The horses were treated with one of 3 treatments beginning on day 5: Group A (positive control) received PSGAG (Adequan, Luitpold Pharmaceuticals, Inc, Shirley, NY); Group B received a compounded solution of acetyl-d-glucosamine (Red Cross Drug, Blanchard, Okla); and Group C received a solution of chondroitin monosulfate (Chondroprotec, Neogen Corp, Lexington, Ky). All horses received the treatments by intramuscular injection every 4 days for 4 weeks and all doses were 500 mg/5 mL. On days 12, 19, 26, and 33, the primary outcome measures were taken for lameness score, carpal flexion, stride length, and carpal circumference. The study was blinded because the clinician evaluating the outcome measures was unaware of the treatment group assignments. The group means for percent recovery of model-induced deficits in these parameters was subjected to statistical analysis.

PSGAG was significantly (P < .05) more effective in the recovery of model-induced deficits in all parameters than were chondroitin and glucosamine injectable solutions, and there was no significant difference between the 2 test drugs. In this test system, these 2 compounds, often sold as “generic” versions of PSGAG, were significantly less effective than PSGAG.

Introduction

Veterinarians, horse owners, and trainers have seen a number of therapies offered in recent years for equine arthritis and traumatic joint diseases. Some of these are supported by solid scientific research and are approved by the Food and Drug Administration for the treatment of equine joint diseases including sodium hyaluronate, polysulfated glycosaminoglycan, nonsteroidal anti-inflammatory drugs, and corticosteroids. The clinical efficacy of these products has been well established.¹ Many other products referred to as nutraceuticals have proliferated and claim to provide chondroprotective benefits in injured equine joints. Most of these products contain chondroitin sulfate and/or glucosamine sometimes combined with other ingredients. Studies of the oral absorption of these products have produced conflicting results in humans and other species.² Studies of the efficacy of these products in equine joint disease have also produced mixed results. Reduction of lameness was reported in an uncontrolled clinical trial.³ No efficacy was seen in a negative controlled study of the same nutraceutical in the CFA carpitis model.⁴ In a recent controlled trial, a different nutraceutical was shown to improve gait symmetry (as measured by kinematic gait analysis) in horses with tarsal degenerative joint disease (DJD).⁵ More controlled clinical studies of these compounds are needed to establish whether they have a useful role in the treatment of equine joint diseases.

Other companies and compounding pharmacists are now selling products claimed to be “generics” of popular drugs such as Adequan and Legend (Luitpold Pharmaceuticals, Inc). These products do not fit the legal definition of a generic drug and are not approved by the FDA. They include a chondroitin monosulfate labeled as a topical wound healing product (Chondroprotec, Neogen Corp) and compounded acetyl-d-glucosamine solutions. Both products are recommended off-label as Adequan substitutes (despite significant chemical differences) with the dose and treatment regimens identical to the approved dose regimen for Adequan. There are no reported studies of the efficacy and safety of these products in horses. The objective of this study was to evaluate the efficacy of parenteral chondroitin monosulfate and compounded acetyl-d-glucosamine by comparing them with an approved product of known efficacy (intramuscular PSGAG) in a well-established model of equine carpal inflammation.