Onsior/robenacoxib

[silverfish]

This is a fairly new drug for osteoarthritis here in the UK. It's an NSAID and supposedly better tolerated by the oldies.

 

Anyone heard of it? Have any input/experiences?

[kudzu]

Very interesting. Had not heard of it. Looks like it has already been approved in USA for use in cats, perhaps only for post op pain. Think they've started the process for dogs. What I found most interesting is the statement, "All dosages of robenacoxib produced significant dose-related inhibition of COX-2 (estimated ED(50) was 0.52 mg/kg) but no inhibition of COX-1." I know little of medicine, human or animal, but I thought all the NSAIDs currently sold here did suppress COX-1 to at least some extent even if small. The suppression of COX-1 is one of the reasons for adverse GI effects, isn't it?

 

If you find out more about how dogs being prescribed this are reacting to it, good or bad, please let us know.

[Batmom]

It actually sounds quite a lot like Rimadyl -- very similar mode of operation, similar range of side effects -- but maybe a bit more kidney-toxic.

[kudzu]

Except that carprofen does still have some Cox-1 inhibition IIRC.

[Batmom]

Wouldn't be surprised if they both did to some extent. But AFAIK, Rimadyl is pretty COX-2 selective. That's why it was developed in the first place .

[kudzu]

Batmom, what makes you say it maybe more kidney-toxic? No saying it wouldn't be. Just trying to get info.

 

Did go do some looking, hardly comprehensive though. Short story is the bits I found seem to support what is in the Merck Vet Manual which lists:

"The exact mechanism of action of carprofen is unclear. Although it has greater selectivity for COX-2 over COX-1, carprofen is considered a weak COX inhibitor. In vitro canine cell line assays indicate that it is 129-fold selective for COX-2, whereas in vitro canine whole blood assays indicate it is 7- to 17-fold selective for COX-2, equine whole blood assays indicate it is 1.6-fold selective for COX-2, and feline whole blood assays indicate it is 5.5-fold selective for COX-2."

 

I did find robexacoxib study abstracts for horses, cats & dogs. For cats it states, "Based on a clinically recommended dosage regimen of 2 mg/kg, it was predicted that the corresponding mean robenacoxib blood concentration over the first 12 h after drug administration corresponded to 5% inhibition of COX-1 and 90% inhibition of COX-2." http://www.ncbi.nlm.nih.gov/pubmed/19161453 That does appear to be significantly more selective for Cox 2 over Cox 1 in comparison to carprofen. (But what do I know? ) The horse study doesn't seem to show the serum levels of Cox 1 & 2 so I can't really compare.

 

The dog study on robenacoxib said, "Pharmacokinetic–pharmacodynamic simulations indicated that all dosages of robenacoxib were associated with marked inhibition of COX-2 (median Emax 74–99% inhibition). For the highest dosage of robenacoxib (40 mg/kg in Study 1), the upper limit of the 90% tolerance interval was associated with 71% inhibition of COX-1 at Emax, but 50% inhibition persisted for only 3.5 h. This level of inhibition of COX-1 with robenacoxib was not associated with any detectable toxicity, suggesting that the high safety index of robenacoxib in dogs is a function of both its high COX-2 selectivity and short residence time in the central compartment." http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2885.2010.01209.x/abstract That doesn't really give an equivalent basis for comparison, for me at least. It doesn't appear to entirely back up the "no inhibition of COX-1" but 40 mg/kg is 20-40x higher than the recommended 1-2 mg/kg.

 

Just sharing. Though I know the level of Cox 2 selectivity isn't the only thing that determines safety & effectiveness, it is a major component that determines adverse effects. Carprofen is a good product with a good safety record even compared to some newer drugs. Still, I really like the idea of a drug with even less Cox 1 inhibition. So it will be interesting to see what happens in real life with this new drug.

[Batmom]

Take a look at the product inserts and adverse effects lists for each drug .

 

 

ETA: It's possible that this drug might work better for pets who don't get along with one or the next other NSAID, but I wouldn't expect it to offer significantly better pain relief and I would expect it to offer @ the same or worse side effects.

Edited December 11, 2011 by Batmom

[silverfish]

Well, that's pretty much what I suspected I would hear. Not a miracle drug, may possibly be a little easier on the older/more sensitive ones, but still carrying the usual NSAID side effects to some extent.

 

Thanks for all the input! I knew I could count on you.

[Batmom]

Could be my opinion will change when there's more experience with the drug. And, you never know but what an individual dog will do better with that one than the others.

[silverfish]

True - my Jack did a LOT better on Metacam than Rimadyl, even though to all intents and purposes they are pretty much the same thing.

[GreyTzu]

Sounds like Robaxin. No experience in our household, either canine or personal.

[kudzu]

Sounds like Robaxin. No experience in our household, either canine or personal.

Yeah, sounds the same & yet it isn't. Gets darned confusing & leads to situations like this one when I was working late & called BF to tell him which med to give a foster dog, "No honey, it enalapril not anipryl. No, no look behind the anipryl for a different bottle that starts with an E." "Well," comes the tired & frustrated voice. Here's one that starts with an E, Eckerd."

[Guest budsmom]

I would be surprised if it's recommended for cats. NSAIDs are very hard on cats, and are generally used very sparingly if at all. Most cats are given narcotics for pain because NSAIDs are so hard on their livers. I think my vet gives a shot of an NSAID post op for cats, but sends a narcotic or some other pain med home for use. When my kitty had his leg amputated this fall, they sent him home with Buprenex.