Toxicity tests on animals ‘cannot be justified on scientific grounds’ according to new study


A new scientific paper published today, building on previous findings that using dogs in experiments to predict the safety of new drugs in humans is no better than tossing a coin, has found that tests on other species are little or no better.

The new peer-reviewed study, authored by FRAME Life President Professor Michael Balls and the BUAV’s Dr Jarrod Bailey and Michelle Thew and published in the scientific journal ATLA (Alternatives to Laboratory Animals), is the most comprehensive published analysis to date of the value of using animals for predicting drug safety in humans.  It is based on the largest database of animal toxicity studies yet compiled and uses the most appropriate statistical methods to determine the evidential weight provided by animal data to the probability that a new drug might be toxic in humans.

Laws and regulatory agencies worldwide currently require that drugs are tested on animals prior to clinical trials on humans, and more than 290,289 animals (including over 2,755 dogs) were used in such experiments started in 2013 in Great Britain alone.  Despite these numbers, drug development is facing serious difficulties: new drugs and drug pipelines are at all-time lows.

To date, very little research has been carried out examining whether experiments on animals really are useful in advancing the development of drugs for human.  This new paper addresses this knowledge gap, and will have widespread implications for the pharmaceutical industry.

The key findings of the new analysis demonstrate that the absence of toxicity in dogs, rats, mice and rabbits in human drug trials provides essentially no insight into the likelihood of toxicity in humans. This means that, for example, if a new drug has (based on prior information) a 70% chance of not being toxic in humans, then a negative test in these four species would only increase this probability to an average of just 75%. The animal tests therefore provide essentially no additional confidence in the outcome for humans, but at great ethical - and financial - expense.

The paper concludes “the preclinical testing of pharmaceuticals in animals cannot currently be justified on scientific or ethical grounds”.

CEO of the BUAV, Michelle Thew, said: “Animals such as dogs, rats, mice, and rabbits have been used in drug testing for well over half a century.  Given the level of public concern about animal experiments, and the fact that many in the pharmaceutical industry say they would prefer not to use them, one may expect overwhelming scientific evidence to support the continued suffering inflicted on these and other animals in the name of medical research. Yet the overwhelming evidence in our new paper demonstrates that these tests are not fit for purpose and provides proven scientific reasons to end the use of animals in such research.”

The authors hope the paper will encourage Pharma and other stakeholders to engage fully in constructive discussion and debate and to increase the search for more reliable testing methods not involving the use of animals.