Chemical Difference: Palosein v. Pentosan v. Adequan
OK, I have done some basic research to try to figure out what the actual difference between these 3 drugs is/are. Why one would be used over another or with conjunction and so forth. I want to get the information of systematic equine arthritis drugs all in one place. I'm going to be really technical and then try to make a summary for each drug in layman's terms, please feel free to educate and correct when necessary.
I'm not looking for anecdotal stories, there are plenty of threads of those, so please refrain.
It has been stated before on this forum that Palosein is the old form of Pentosan. What I've found (sourcing using NCBI and PubMed mostly) is that they are not chemically the same. My research is saying that Palosein(aka Orgotein) is a "super oxide dismutase," it inhibits free-radicals in the the synovial fluid which would cause reduced viscosity of the synovial fluid. OK, that sounds like it would help arthritis in horses by improving the quality of the synovial fluid in the joints. However, this would not seem do a lot for already damaged joint surfaces IMO. IIRC, Reed didn't you say that this was no longer available for veterinary use in the US? I did find this from the FDA, looks like its still available through veterinarians. http://www.accessdata.fda.gov/script...cfm?dn=045-863
Pentosan Polysufate (Elmiron and Pentosan) is a derivative of heparin(blood thinner) without the anti-coagulant properties. In humans, it's prescribed to alleviate irritation of the bladder walls for those that suffer from institial cystitis. There are papers about using PPS as a disease modifying osteoarthritis drug in humans (http://www.biomedcentral.com/1472-6904/10/7) with favorable results. Another study looked at PPS and its effect on MPCs (cells that can differentiate into cartilage cells, or make more cartilage) http://arthritis-research.com/content/12/1/R28 . This is only one study, but it had also favorable results in that MPC proliferation was significant after 3 days of treatment with PPS. This information sounds like not only does PPS have pain relieving qualities, it also aids in the process of rebuilding cartilage. As this has been hashed out before, this is available in the US by vet Rx requiring it to be compounded for veterinary use.
Polysulfated glycosaminoglycan (Adequan, PSGAG) is also an analog of heparin and is similar to mucopolysaccharides that naturally occur in cartilaginous tissue. PSGAG inhibits proteolytic enzymes that degrade proteoglycans(eat up cartilage tissue). This prevents or reduces decreased connective tissue flexibility, resistance to compression and resiliency.There have also been claims that PSGAG can also increase synthesis of new proteoglycans and reduce inflammation by reducing concentrations of prostaglandin-2 and increase hyaluronate concentrations in the joint, however newer studies are showing that this is unfounded. So, PSGAG inhibits the breakdown of cartilage and possibly assists in making new cartilage and has anti-inflammatory action as well. Adequan is available by vet Rx in the US.
So roughly outlined, it looks like PPS is the only one with "proven" anti-inflammatory properties. Palosein looks like with would help in combination with an anti-inflammatory since its main process is to improve the viscosity of synovial fluid. PSGAG is mainly seen in reducing injury or severity of injury(stops or slows down the athritis process). PPS seems like it has the most proven effects of rebuilding connective tissue/cartilage as opposed to PSGAG.
Comments? I haven't touched on Hyaluronic Acid for the only reason that it's usually used in conjuction with one of the above drugs, though it looks like Palosein has a similar effect through a different means of chemistry (inhibiting v. adding more lubricant).
Where am I and what am I doing in this handbasket?
As far as I know, while palosein is still approved for use in horses in the US, but nobody manufactures or distributes it, that's the real issue.
More's the pity because I never saw a bigger difference in soundness than with palosein, although it has not ever been used as a drug for joint issues in my limited experience. I believe it is approved in Europe (people and humans) as an anti-inflammatory type treatment for muscle injuries? It's been 12 years since I saw it used so forgive me if my recollection is wrong, but I swear, that's what I recall.
We used it on my horse injected into the digital cushion. The vet I worked with said it didn't always have much effect, however on some horses it was absolutely amazing, like Lazarus from the dead sort of amazing. My horse fell into the latter category. He went from itty bitty short strided footsore horse with all sorts of corrective shoeing insanely sound overnight that I sat there on the end of the lunge line watching this horse who never misbehaved on the lunge line and was now ripping around (both egg bars went flying) and bucking because for the first time in months he felt awesome. I think I left him barefoot for another 3 weeks because he was sound and then just had the farrier go back to basic shoes on our next regular appointment and we never looked back. But I did have another palosein injection done a few months later and it wasn't the same radical improvement (although he wasn't lame either).