No drug is tested on humans, except all the drugs tested on humans

Another day, another “science” piece on Comment is Free that plays fast and loose with the science. Let’s get this over with.

When a dog with a life-threatening uterine infection was recently carried into my veterinary practice, I was confident we could save her. Following a rapid infusion of intravenous fluids and antibiotics, I performed emergency surgery. Partly because of the drugs she was given, “Annie” recovered well. I had the luxury of knowing they had all been tested on other animals of the same species, and were unlikely to inadvertently cause any harm.

Unfortunately, my brother does not have that luxury. He works as a resident in a hospital emergency department, and although the drugs he uses have also been thoroughly tested on animals, this doesn’t provide quite the same level of comfort. It is one of the tragedies of modern medicine that adverse reactions to pharmaceuticals cause thousands of potentially avoidable deaths.

Sadly, dogs are just as susceptible to drug side effects as humans are. But more importantly, “I had the luxury of knowing they had all been tested on other animals of the same species […] my brother does not have that luxury“? That sounds to me like a fairly strong implication that drugs are never tested on humans. This is obviously, blindingly untrue. Any drug has to go through multiple stages of human testing, from safety tests in healthy volunteers, to short laboratory tests, to huge randomised trials involving thousands of patients – sometimes lasting decades. At every stage of the process, the patients are carefully observed, and (in theory*) any side effects are noted and analysed. Indeed, Andrew Knight admits this in the next two paragraphs:

Modern drugs are more carefully studied than ever before. After lengthy tests on animals, those considered safe, and potentially effective, enter very limited human trials. About 92% are then weeded out and deemed unsafe or ineffective.

The remaining 8% are some of the most closely scrutinised compounds on the planet. You might be forgiven, therefore, for assuming they are safe. But at least 39 studies over three decades have ranked adverse drug reactions as an important cause of hospital deaths. Only heart disease, cancer and stroke are more reliably lethal.

No drug is ever tested on humans, except for every single drug ever, all of which are tested on humans!

Adverse drug reactions are always something drugs companies should try to reduce, but for the vast majority, it’s not the case that they weren’t picked up in testing – cases like thalidomide, where no-one knew the risk until pregnant women started using it, are the exception, not the norm. Most adverse side effects that are known about and carefully measured, and the doctor will have had to measure up the risks versus the benefits for each before prescribing the drugs – if you look at the study he links to, 75% of severe reactions to drugs are known side effects caused by dose, and a lot of the rest are allergic reactions. As the paper itself says “This may suggest that many [adverse drug reactions] are due to the use of drugs with unavoidably high toxicity.” We could test as hard as possible, but there would always be drugs that could never be 100% safe.

The author of the piece, Andrew Knight, has written a book on the subject, linked to in the piece (it also apparently focuses more on data than debate, which is usually good, though admittedly the only scholarly review I could find accused the book of bias in the way it analysed this data – Knight’s rebuttal is here), and he does seem to be someone knowledgeable in the field. But that doesn’t change the fact that this particular column is bad. It defends a reasonable viewpoint – let’s try to find ways to test drugs on computers or in petri dishes rather than having to use live animals – with nonsense. Even if we did everything this column recommends, and managed to completely replace animal testing with simulations, I don’t see how it’d cause a significant change in the number of reactions to drugs. It might plenty of other good effects – not least, reducing the number of animals used, of course – but that wouldn’t be one of them.

* Sadly, some pharmaceutical companies have tried to hide the safety data for their drugs – just last week, GlaxoSmithKline was fined $3 billion for doing so – but as things stand, this would happen regardless of whether the safety data was from animals, humans or computers.


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