What viagra did to beagles....

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What viagra did to beagles....

Postby cheerleader » Sat Jun 14, 2008 1:54 pm

An interesting essay on why animal testing is insufficient-

"There are plenty of examples of substances that have appeared to be safe in animals and turned out to be toxic in humans, and vice versa. It wasn't long ago that six men in England who volunteered for an experiment to test a drug designed to treat diseases such as rheumatoid arthritis, leukemia and multiple sclerosis by dampening the body's immune reaction, ended up in hospital, some suffering permanent organ damage. Mice, rats, rabbits and monkeys had shown no ill effects at all

There are also cases of substances that cause problems in animals, but not in humans. If we used dogs as the standard animal to test food components, we could say good-bye to chocolates. This delicacy is highly poisonous to dogs! Twenty-five grams of chocolate, a quarter of a chocolate bar, can kill a dog within a few hour.

Viagra raises another interesting point. When it was tested in beagles, it caused severe stiffness. Not where it counted, but in the neck. Researchers referred to this as "beagle pain syndrome." They also found that Viagra constipated mice and caused the livers of rats to swell."

link

BTW, I learned how to do blue links!!!! (finally)
Thanks, NHE-
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Postby Grumpster » Mon Jun 16, 2008 8:30 pm

The animal models are certainly not perfect that is for sure. Interesting on the Beagles though. The other option is to test only on humans? It is a pretty tough thing to develop new drugs and therapies. Let's hope that they can wade through all the regulations, complications and moral issues and find something fast!! G
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Postby jimmylegs » Mon Jun 16, 2008 8:45 pm

maybe the pills got caught in their little throats hehehe
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Postby MrsGeorge » Tue Jun 17, 2008 2:50 am

I live in England. That drug trial was headline news for ages. Some of those men are still recovering from it.

I don't know why the thought of giving beagles viagra entertains me so much but it does!
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Postby cheerleader » Tue Jun 17, 2008 8:41 am

Yeah,
the beagle image gave me a giggle, too, Mrs. George. Stuck in their throats, JL! lol!

The real hope is in testing human cells- that gets the medicine right to the source. This method could potentially fast-track trial meds.

"Techniques are being developed whereby liver or skin cells can be placed in thousands of tiny wells on a single dish, and different doses of chemicals can be systematically applied and the effects on the cells noted. Researchers are working on correlating results from such experiments with animal and human data, and within a few years we may in fact be able to test those thousands of chemicals to which we are exposed in a more reliable fashion. The next canary in a coal mine may very well be an isolated liver cell in a laboratory dish."

Hope this happens soon. The AEA model in mice just isn't working.
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Postby ElmerPhd » Wed Jun 18, 2008 3:05 am

The thing about the trial in England was that it was poorly designed in the first place. I don't know the details, but from what i remember about the lengthy coverage it got at the time, that's my impression. Of course with hindsight, they should have administered the drug to the patients one-at a time in a staggered way and started off with very small doses to closely monitor the effects. That was the most important problem with the design, they gave all 6 guys a fairly large dose and all at the same time so when they all started reacting very badly they weren't able to cope and stop the trial in time.

Those in vitro tests are already happening, cheerleader, and are a natural progression of techniques that have been in use for decades. The problem is that high throughput screening (HTS) like that is only going to let you know whether a compound is toxic to the cells you apply it to. You can't be absolutely sure what the metabolites or breakdown products of the compound will be or what effects they will have.

Interesting opinion on the AEA (did you mean EAE?) model in mice. As far as i understood it, this was actually a fairly reasonable model as far as animal models go. Like all models, it isn't perfect, but helps researchers eliminate potential dead-ends before too much time is spent developing them. It's also worth bearing in mind that most drug companies nowadays have a HUGE number of compounds they keep in storage, from which they will screen potential leads (using HTS technologies) for particular diseases. As new screening methods or new information about possible targets are developed and discovered, these libraries are returned to for re-analysis.
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Postby art » Tue Jul 01, 2008 9:44 am

Turns out that chocolate isn't quite so poisonous to dogs as you indicate. It takes 1.25 *pounds* of chocolate to kill a 20 lb dog
http://www.howstuffworks.com/question348.htm

My friend's 50 lb dog managed to get into my closed suitcase, pull out a gift wrapped box of chocolates, unwrap it, open the box, and consume 2lbs of chocolate. And then had the nerve to have absoultely no apparent consequences - not even vomiting.

Here's another site that talks about the danger, but seems to think the large quantities aren't that unusual http://www.straightdope.com/classics/a5_211.html

None of this is to say you should be feeding your dog chocolate, but the difference in biology isn't as extreme as some would have you believe.

Mind you, I'm a huge proponent of human testing for human diseases. The mice are all set for disease cures at this point, time to move on to people.
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