The alternative treatment on my radar, from before I heard about...

The alternative treatment on my radar, from before I heard about pentosan, is regenosine. This is pre-clinical, so a long way from market, if it ever gets there. Not part of the competitive landscape for PAR for many years. However, it shows dramatic results in restoration of cartilage from complete loss, in mouse models.

Regenosine is an intra-articular injection of liposomal adenosine. Adenosine is a particularly unstable molecule, and encapsulating it in liposomes, which are onion-skin like bundles of lipid bilayers (cell wall material) helps protect it. Adenosine acts at the cell surface adenosine receptor and suppresses NF-kB (ie suppresses initiation of inflammation). So it works by a different mechanism to pentosan, but probably induces some common downstream effects.

It has not yet been put into humans, and is not in Phase I. The startup company has spun out a company Vetosine to treat OA in dogs, but there's no published work on dogs yet as far as I can see.

So its a long way off, but if it ever becomes available I will be heading to my nearest horse doctor in the hope of regenerating my lost cartilage.

http://regenosine.com/technology

https://www.nature.com/articles/ncomms15019