Adequan has been studied extensively in both in vitro scientific experiements and in vivo clinical studies. In vitro studies have found PSGAG to

• inhibits proteolytic enzymes that can degrade the chemicals in the joint
• increases the synthesis of proteoglycans.
• reduce concentrations of prostaglandin E 2 (released in response to joint injury)
• increases hyaluronate concentrations in the joint

If it works in the horse as well as the petre dish this should result is less inflammation and a better joint environment. Whether PSGAG actually slows the progress of DJD is less clear and the experimental data contradictory.

Studies with horses with experimentally induced arthritis have supported the use of 250 mg PSGAG administered intraarticularly into the equine joint disease. In these studies the joint cartilage was considerably healthier with the use of PSGAG when compared with controls though there was no effect on preexiting lesions of the joints. However when PSGAG is used intramuscularly (500mg) no effect was found and currently experimental and clinical evidence for its use is lacking for this use. One of the reasons the use of PSGAG has moved to primarily IM use is the fear of inducing infection in the joint. However the concomitant administration of 125mg amikacin largely eliminates this complication.

The only reports of the use of PPS in horses are anecdotal and the drug only approved in Australia for use in horses. PPS is a heparinoid compound that is derived from beechwood hemicellulose instead of animal sources. Commercial products available include Cartrophen Vet (for canines) and recently Pentosan Equine Injection (PPS sodium 250 mg/ml), both licensed in Australia. In studies with sheep (3 mg/kg body weight once weekly for 4 wk.) IA injections of PPS for 4 wk improved joint function including lameness, flexion, and improved the radiographic and histologic appearance of articular cartilage of the stifle.

Chondroprotec has been advertised as a generic Adequan (a polysulfated GAG) but laboratory analysis of this compound has shown that it is actually chondroitin sulfate (a mono-sulfated GAG) with a molecular weight of 16,000 - 33,000 k Daltons which is also different than Adequan. In studies against Adequan it was not as useful at curbing acute joint inflammation.

Acetyl-d-glucosamine is another product marketed as a generic Adequan but is not chemically the same as PSGAG. It is an aminomonosaccharide with a molecular weight of 1000 k Daltons. In studies like the Chondroprotec above, it was not as good at treating acute joint inflammation as Adequan.