Friday, April 11, 2008

Thalidomide tragedy, side effects, history

Drug testing on animals

What is Thalidomide

Thalidomide was one of the greatest cases in history of a drug disaster tragedy being caused by animal research.

First of all, Thalidomide had been tested on animals extensively prior to its marketing.

Even now, despite the clinical evidence to the contrary, British health authorities like the Medical Research Council maintain that the vast bulk of evidence from laboratory and animal tests is against thalidomide having any genetic effects.

The tragedy caused by Thalidomide in the 1960s was due to its teratogenic effects, ie effects on the foetus. Teratological effects of drugs were little known then. They were brought to public attention because of the Thalidomide tragedy on humans, therefore only after it. How on earth could animal researchers have thought of those effects before the disaster?

Even after the Thalidomide caused birth deformities in humans, researchers tried to reproduce the same effect in dozens of species of lab animals without success.

Take a look:

"As a consequence to the thalidomide tragedy there has been a marked upsurge in the number of animals used in testing of new drugs. Also drugs are now specifically tested on pregnant animals to supposedly safeguard against possible teratogenic effects on the human foetus. Vivisector's claim that if such tests were carried out prior to thalidomide's release, birth deformities in humans would have been discovered. This is of course sheer nonsense. 'In pregnant animals, differences in the physiological structure, function and biochemistry of the placenta aggravate the usual differences in metabolism, excretion, distribution and absorption that exist between species and make reliable predictions impossible.' (15) (Dr Robert Sharpe, former senior research chemist.)

"In fact when the link between human foetal abnormalities and thalidomide was established (through clinical observation), the world-wide explosion of animal testing, using a large range of species, proved very difficult to duplicate the abnormalities. (16) Writing in his book Drugs as Teratogens, J.L. Schardein observes: 'In approximately 10 strains of rats, 15 strains of mice, eleven breeds of rabbit, two breeds of dogs, three strains of hamsters, eight species of primates and in other such varied species as cats, armadillos, guinea pigs, swine and ferrets in which thalidomide has been tested teratogenic effects have been induced only occasionally.' (17) Eventually after administrating high doses of thalidomide to certain species of rabbit (New Zealand White) and primates could similar abnormalities be found. However researchers pointed out that malformations, like cancer, could occur when practically any substance, including sugar and salt, be given in excessive doses. (16)" [my emphasis]

Thalidomide's history in the USA

Some apologists of animal experimentation say that the reason why Thalidomide was never approved by the FDA (Food and Drugs Administration, the US agency responsible for drugs licensing) in the US is that the FDA reviewer had previous experience in animal research and had refused to clear the drug for sale until better documentation of its effects were provided.

The reality is that the FDA reviewer in question, Frances Oldham Kelsey, had doubts about Thalidomide's safety because of side effects shown in human clinical trials.

The FDA website is very clear on this. In Frances Oldham Kelsey: FDA Medical Reviewer Leaves Her Mark on History it says:

"In December of 1960, three months after Richardson-Merrell submitted its application, the British Medical Journal published a letter from a physician, Leslie Florence, who had prescribed thalidomide to his patients. Florence reported seeing cases of peripheral neuritis, a painful tingling of the arms and feet, in patients who had taken the drug over a long period of time." [emphases added]

And here is another biographical note on Frances Kelsey:

"Dr. Kelsey continued to resist, pointing out in February 1961 that a study in England had indicated the new product caused 'a serious side effect on the nervous systems of patients who took the drug repeatedly,' so she asked for assurances that such side effects wouldn't occur. By May she had developed a theory that if thalidomide caused paralysis of the peripheral nerves, the drug probably would cause greater damage to the developing embryo." [emphasis added]

Better control

The answer is: better control of the effects of medicines after they have been marketed.

"We need to encourage doctors and drug companies to watch for, report and take note of side effects in order to protect patients properly. If proper drug surveillance techniques had been available in the 1960s the thalidomide problem would have been picked up much earlier. We still don't have proper post marketing trials in place." (from the source above)

Testing on humans is going to happen anyway, because any new drug which is marketed is an unknown, due to the unreliability of previous animal testing.

Let me repeat: you cannot make an unreliable method reliable by counterexamples.

Even if you happen to encounter cases where animal tests results have not been refuted by their application to humans, this does not alter the unreliable status of the method.

There are cases where there is a correspondence between human and non-human animals. But how do we know that? Because we transferred the results of animal testing on humans. That is, for all practical purposes, we tested them on humans.

It is an unavoidable fact.


Douglas Michael Massing said...

As I recall from the time - and I have no better source at hand than my memory - in addition to the British report mentioned, thalidomide heroine Frances Oldham Kelsey did base part of her resistance on already completed animal studies, but not in the way the "apologists" are paraphrased. Ms. Kelsey saw not evidence of safety in the animal studies, but evidence of nothing: since the drug did not act as a tranquilizer on the animals tested, she reasoned, no inference on the way the drug (mis)behaved in humans could be based on the way it acted in non-human animals. The probable source of this memory is Life magazine, but only its pictures seem to be available online. Perhaps someone with access to a library archive could check this out.

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