Vioxx Withdrawn

[Guest]

Vioxx was voluntarily withdrawn from the market by Merck today. They found that there was an excess of heart attacks and strokes among people who took it.

The website www.vioxx.com has been overwhelmed so I cannot find out what the procedure is for getting refunds etc. It would be best to call the pharmacy where you got it to find out what to do.

It seems to me that the mechanism of action is something like this. Aspirin irritates the lining of the stomach and inhibits platelets. So does ibuprofen. Therefore, there must be something similar in the sites where these drugs work. Vioxx was designed to be non-irritating to the stomach. It did that. It also did not inhibit platelets. Without platelet inhibition, there was an increase in heart attacks and strokes.

 

[JimChicago]

Without platelet inhibition, there was an increase in heart attacks and strokes.

Did it increase the risk of stroke relative to NSAID's or would it have increased the risk on its own not just in comparsion to NSAID's but also in comparison to people who did not take any aspirin or NSAID's?

I still find it a little confusing the difference between inhibiting paltelet aggregation to decrease the liklihood of strokes and warfarin/anti-coagulation to decrease the liklihood of strokes. I guess I'm just wondering if there's some overlap where platelet aggregation inhibition and warfarin together could minimize stroke probability versus warfarin alone?

 

[tobagotwo]

One of the things that was pointed out was that the effect was only observed over long-term use (I believe 18 months was mentioned, but I read it this morning, and it is almost midnight).

If someone has a prescription for short-term use, such as a few weeks, there was no data to support increased risk.

I have some left from the operation, and I would still use them if I felt they were relevant to a situation. There are not enough to go for more than a week or so.

Best wishes,

 

[Guest]

I have had to had time to read more about it now. They were conducting a study to see if Vioxx could reduce the risk of colon polyps. Since no drug has ever been shown to do this, the study was comparing Vioxx with placebo. Evidently the rate of MI and stroke did not differ until 18 months on Vioxx. There were some earlier suspicions that there were more MIs and strokes with Vioxx but nothing concrete. This was considered proof since it was a randomized double-blind controlled study. Once Merck found this out, they would have been liable for suppressing evidence had they not at least announced this. They must have figured that once they announced the findings that sales would drop off to the point where they would not be able to make money after the lawsuits were defended, so they decided to withdraw it.

As for the question about warfarin and antiplatelet agents, my opinion is this. There is no proof that the combination of warfarin and an antiplatelet agent is any more effective than warfarin alone except for people with mechanical mitral valves (and of course 2 mechanical valves.) Mostly strokes are caused by the blood flow past a mechanical valve not being the same as past a natural valve. Thus eddy currents are set up behing the mechanical valve. This leads to stagnation which leads to a clot forming. Warfarin works best in stagnation situations. But when the clot starts to form, then platelets get involved. So antiplatelet agents add a little bit more protection but they also increase the risk of bleeding.

So it pretty much comes down to pick your poison.

 

[ALCapshaw2]

SNIP

As for the question about warfarin and antiplatelet agents, my opinion is this. There is no proof that the combination of warfarin and an antiplatelet agent is any more effective than warfarin alone except for people with mechanical mitral valves (and of course 2 mechanical valves.) Mostly strokes are caused by the blood flow past a mechanical valve not being the same as past a natural valve. Thus eddy currents are set up behing the mechanical valve. This leads to stagnation which leads to a clot forming. Warfarin works best in stagnation situations. But when the clot starts to form, then platelets get involved. So antiplatelet agents add a little bit more protection but they also increase the risk of bleeding.

So it pretty much comes down to pick your poison.
(Says AL Lodwick, tongue in cheek)

Thanks for that informative explanation AL.

It seems to me that for short term use, VIOXX is still a viable and useful product. I guess the LIABILITY issue was the untimate killer of the product.

It is interesting to note that other COX2 inhibitors claim to not have this problem, but then they have NOT undergone the same testing... Let the buyer beware!

'AL Capshaw'