Drug development and testing

In a nutshell

Drugs must be rigorously tested before being approved. There are two stages of drug testing: preclinical trials and clinical trials. Preclinical trials have three stages: computer models; human cells and tissue testing; and animal testing. Clinical trials are done firstly on healthy humans and then patients with an illness. Peer-reviewed results that show the drug to be effective will it allow to be approved.

Preclinical testing

Drugs are first tested using computer models and then on human cells and tissues in the lab. Next the drugs are tested on live animals such as mice. This determines the efficacy, the toxicity and the dosage of the drug.

Efficacy	Whether the drug works and has the effect you are looking for.
Toxicity	How harmful the drug is and if it has any side effects.
Dosage	The concentration of the drug that works best and how often it should be taken.

Computer models

Computer models simulate a human's response to a drug, so you don't need live animals at this stage. They can identify promising drugs to be tested at the next stage. However, it is not as accurate as actually studying the effect of the drug on a live organism.

Human tissues

The drugs can then be developed further by being tested on human tissues. However, you cannot use human tissue to test the effect of the drugs on whole/multiple body systems.

Example

Testing a drug for blood pressure must be done on a whole animal with an intact circulatory system.

Animal testing

The final step requires testing the drug on live animals. In the UK, the law states that any new drug must be tested on two different live animals. It may be considered cruel, but it is the safest way to test if a new drug is dangerous before it is given to humans.

Clinical testing

If the drug passes the animal testing it is then tested on human volunteers in clinical tests.

1.	First the drug is tested on healthy volunteers to ensure it doesn't have any harmful side effects when the body is working normally.
2.	A very low dose is given, this is increased little by little.
3.	If the results are good, the drug can then be tested on patients who have the illness.
4.	The optimum dose is found. This is the dosage of the drug that is the most effective and has few side effects.
5.	Patients are put into other of two groups. Group $1$ is given the new drug and group $2$ is given a placebo. A placebo is a substance that doesn't do anything, like a sugar pill.
6.	The doctors will compare the two groups of patients and look for a significant difference.
7.	Clinical trials are blind so the patient doesn't know if they have received the placebo or real drug.
8.	They're often double-blind, meaning the doctor and the patients don't know whether they've received drug or placebo until after the results have been collected.
9.	These results cannot be published until they have been peer reviewed. This involves other expert scientists and doctors looking at the results to prevent false claims.