Why do we need to do animal experiments? Part 1 – Drug discovery

Animals are an invaluable resource in all areas of biology and biology-related research, and cannot be replaced by ‘alternatives’ as advocated by many animal rights activists and many Green Parties across Europe. In this series of posts, I will explain several interconnected reasons for experimenting on animals drawing examples both from everyday life and hard science. I will also explore the ethical dimensions of using animals and consider whether the legal framework we have in place is fit for purpose. To read this in its native environment, click here (it’ll make the author so much happier)

Subscribe to Blue-Genes.netDrug discovery is the easiest to understand: in order to discover and develop safe drugs that can save human lives, we experiment on animals. The Green Party of England and Wales disagree. Here is an excerpt from their Animal Protection policy:

Experiments on animals are unreliable as a guide to human biology. Different species react differently to drugs and toxic substances. Many drugs that cause damaging side-effects in people have passed animal tests. There are viable alternatives to animal testing including epidemiology, the use of cell cultures, human tissue and computer simulation. The Green Party would redirect research funding to such alternatives.

These are commonly repeated beliefs from animal rights campaigners. For example, People for the Ethical Treatment of Animals (PETA), a high-profile group, campaigns against animal testing as one of its core issues. You can see a collection of documents listing their beliefs here.

A counterweight to this group is the Oxford-based pro-animal experimentation group Pro-Test.

So are animal tests necessary for drug discovery and development? I’m going to briefly outline the process of drug discovery and we’ll see whether it’s truly possible. The steps involved in modern rational drug design (the old fashioned way basically just trial, error and luck) are: 1. Drug target identification 2. High-throughput screening for candidate drugs and refinement 3. Preliminary testing of candidate drugs on cells or animals 4. Clinical trials in humans

1. Drug target identification

We now understand how various biochemical ‘pathways’ (chains of interacting components) operate in cells. When we f?nd a pathway involved in disease, we hope that by changing its activity we can slow down or stop the disease process. This means that generally, we are aiming for something when we test drugs and not randomly subjecting animals to experiments.

2. High-throughput screening

To find potential drugs, libraries or collections of ‘drug-like’ molecules are tested for their binding to the target. Anything that binds to a biological molecule might modify its activity and be a potential drugs. Many hundreds of potential candidates emerge.

3. Preliminary testing

This is the contentious part. The drug is tested for its potential. Sometimes we use cells, but often we use ‘animal models’. These are animals that are bred or engineered to have a similar disease process to humans. This allows us to test the potential safety and efficacy of drugs. Although in a few unfortunate cases this method will not pick up dangerous drugs, it usually does.

4. Clinical trials

The drug is tested on humans in several phases of increasingly larger groups starting with just a handful.

What about Computer models?

Mark Chu-Carroll at Good Math, Bad Math made an excellent post answering advocates of computer models:

a simulation can only do what you tell it to. If you don’t already know how something works, you can’t simulate it. If you think you know how something works but you made a tiny, miniscule error, then the simulation can diverge dramatically from reality.

And epidemiology?

Epidemiology is part of the great tradition of experimental medicine and can help identify causative factors of a disease, but it can’ t test a drug’s safety.


Testing drugs on animal is unpleasant. No one likes doing it. Do not be fooled into thinking scientists are using animals unnecessarily for perverse reasons. There is only one alternative to testing drugs on animals: testing them on humans. It is your decision which you value more. That said however, we can all agree that where possible we should reduce usage of animals for experimentation, and that research into ways of doing this should be well funded.

I urge you to read as much as you can on this subject, think for yourselves, and arrive at a rational, evidence-based conclusion. Question everything.

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