Question: Does animal testing only occur when scientists are in the final stages of creating a medicine and are fairly sure that it will not harm the animal or is it one of the first things they do?

Joanna Cruden answered on 16 Jun 2012:

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This is a good question but the answer is not easy to explain, I have summarized as best I can, but for further information please check out this website.

http://www.animalresearch.info/en/drug-development/the-process/

I have also put a picture of a timeline on my profile to give you a clearer idea of the use of animals during the course of drug discovery.

Animals are used both for drug discovery and basic research both are for improving human health and animal health. Animals are also used for environmental research.

It is like a lock and key, the disease is the lock and the cure is the key, to understand how to unlock the lock we have to understand its mechanism, before we can work on making the key.

Basic research is the lock and drug discovery the key!

Drug research

The short answer is for drug development animals are not used for the early stages

However for basic research, where scientists are investigating how a disease, hereditary or spontaneous, affects our systems, animals are sometimes the only way we can see how it affects a whole living organism.

During the early stages for drug research animals are not always used, they are only used if there is no alternative and this is usually part of basic research where we are trying to understand how a disease or condition affects the body. Where they can in basic research and always in drug development scientists use computers to screen structure and processes, which enable them to find a target for the drug/compound.

Thousands of compounds will be screened this way and different structures and simulations are looked at, this means that even before scientists use animals they already have a pretty good idea in theory of how the molecule/ potential drug/compound should work but not whether it will work or whether it will have an affect on other organs in the body.

The next stage of research uses individual cells kept alive in cell culture medium. Initial tests are carried out to see the action of the compounds on individual cells and tissues containing the drug target.

Thousands of drugs never reach the final developmental stage. When starting to develop a drug the company accepts that out of thousand of possible compounds only one or maybe two will make it to full development.

They are studied in several animal models, alongside continuing research into their effects in vitro. These two approaches to research complement each other, as in vitro studies can give information about the specific effects of a drug at a particular site, while in vivo animal studies give information about the effects of the drug on a whole, living system, and how it affects the interactions between different organs of the body. These studies will include a full assessment of drug delivery systems, preliminary safety testing, studies of possible drug interactions and other side effects.

Toxicity testing
Before a potential new drug can be tested on humans its safety must be assessed through toxicity testing. While these tests cannot predict how a human body will respond to the compound, they are used to determine the range of doses that will be used, which organs of the body the compound might affect, how it will be administered, how long and how frequently individuals should be exposed to the substance, and to what extent its chemical structure is intrinsically toxic. By law, these must be determined before it is considered reasonable to test a substance on human volunteers.
Once the drug reaches this stage they go into clinical trials, which are made up from healthy volunteer human subjects.

During the clinical trials on humans toxicology studies continue with animals to investigate the investigating fundamental ways that the drug affects the body often form the last part of the trials.

Even when a drug is approved and goes into the wider population it can still show side effects in the wider population and will then be removed from the market and it may be put back into research or discarded by the company depending on the side effects.

Please let me know if you want me to explain any points further.