Thousands of people have been injured or killed by drugs that were found to be safe for other species
Jerome Burne Thursday May 24, 2001 The Guardian
What do you feel is more important - the life of your child or the life of a few rats? Such stark contrasts are common currency in the heavily polarised debate about experiments on animals. On the one side the misguided sentimentality of the animal rights campaigners, on the other side the tireless pursuit of human happiness and health by the researchers. But since those wide-eyed activists have put animals' rights somewhere on the election agenda, you may be interested to know that there is a totally hard-headed and rational case to be made for saying that animal experimentation has been a scientific and medical disaster. That far from saving lives, it has caused injury and death to thousands and that time and again it has led both re searchers and legislators into a blind alley.
But surely, you cry, we need animal experiments to discover how safe new drugs are before we give them to humans? Well, the combination of fenfluramine and dexfenfluramine, touted as the answer to a dieter's prayer a few years ago, was extensively tested on animals and found to be very safe. Unfortunately it caused heart valve abnormalities in humans. Or how about the arthritis drug Opren? Tests on monkeys found no problems but it killed 61 people before it was withdrawn. And as for having to choose between rats and your child, Cylert, given to children with attention deficit hyperactive disorder, was fine for animals but caused liver failure in 13 children.
The problem is not a new one, in fact it is blindingly obvious - animals are not the same as humans, so drugs that affect them in one way may well affect us differently.
Now this is usually presented as a solvable problem by researchers. We can get an idea of the mechanism from animals and then fine-tune with humans, they say, but it doesn't work like that. Species, even those t hat seem closely related, may function quite differently at a molecular level, and there is no way of predicting what the differences will be.
Rats and mice, for instance, look pretty alike to us, but when it comes to something as basic as whether a chemical causes cancer or not, the results may be totally contradictory. Out of 392 chemicals tested for carcinogenic effects at the American National Institute of Environmental Health Sciences, 96 were positive in the rat and negative in the mouse or vice versa. So which of those are harmful to humans? The institute can't say.
For 30 years they fed high doses of a range of new chemicals to animals to discover if they caused cancer or other damage. The results are recorded in blue books that take up 10 feet of shelving in the institute. But ask how many of the substances might produce tumours in humans at normal levels and no one knows. So what about the ones that didn't harm rodents, how many of them might harm humans? They don't know that either.
The lack of predictable differences between animal and human reactions is something that has bedeviled Aids research. Aids is a high profile disease with a lot of research money available, so it surely makes sense to ignore ethical objections and use chimpanzees. It is surely precisely because their genome is identical to ours, give or take a few percentage points, that they should yield more accurate results than rodents.
Well, no, actually. Out of approximately 100 chimps infected with HIV over a 10-year period only two have become sick. Chimp vaccine trials have proved unreliable too because they don't show the antibody or cell-mediated response to HIV that humans do. Animal experimentation has played only a small role in developing drug treatments to the greatest plague of our time.
And the list could go on. There are drugs that have been held back because they caused dangerous reaction in animals, such as beta blockers and valium, but then turned out to be safe for humans. Legislation to halt the use of asbestos was held up for years because it didn't cause cancer in animals, while the carcinogen benzene continued to be used long after clinicians were worried because it didn't cause leukemia in mice.
All these examples, and many more, have been written up in the specialist journals but until last year they had been scattered. Then a man called Ray Greek, an American medical doctor who specialised in the highly technical field of anaesthesia collected them in a book called Sacred Cows and Golden Geese. He gave a talk in London about it last night.
So was this scientific, rational contribution to the debate about animal experiments warmly welcomed, so medical research could be improved? Supporters of animal experiments are always calling for more public discussion and education.
Of course not. It was ignored.
. Jerome Burne is editor of the monthly newsletter Medicine Today
www.medicine-today.co.uk