Testing medicines
Three main stages of testing
pre-clinical testingA stage of drug development in which a new medicine is tested on human cells grown in the laboratory and then on animals to see if it works.
- The medicines are tested using computer models and human cells grown in the laboratory. This allows the efficacy and possible side effects to be tested. Many substances fail this test because they damage cells or do not seem to work.
- Medicines that pass the first stage are tested on animals. In the UK, new medicines have to undergo these tests. But it is illegal to test cosmetics and tobacco products on animals. A typical test involves giving a known amount of the substance to the animals, then monitoring them carefully for any side-effects.
clinical testingA stage of drug development. A new medicine is tested on humans to find out if it is safe and whether it works.
- Medicines that have passed animal tests are used in clinical trials. There are two stages in human trials. First they are tested on healthy volunteers to check that they are safe. Secondly they are tested on people with the illness to ensure that they are safe and that they are effective. Low doses of the drug are used initially, and if this is safe the dosage increases until the optimum dosage is identified.
Finally, there are long-term human trials and monitoring to check that the medicine is effective over the long-term, and that it does not cause side-effects.
Control groups and clinical testing
People who agree to take part in a clinical trial will be randomly put into either the treatment group and given the new medicine or the control groupA group who receives the existing treatment or a placebo when new treatments are being tested.. Generally the control group is given the treatment currently being used. At the end of the trial the two groups are compared in order to determine if the new treatment is an improvement.
Blind, double-blind, and open-label
It is important to eliminate, or at least limit, bias A preconceived notion or idea about a thing, person or group of people based on personal belief. in clinical testing wherever possible. A placeboAn inactive substance made to resemble a drug for researchers to use as a control. is a treatment which looks exactly like the new medicine but it has no active ingredient in it.
In a double blind trial A medical trial to test a drug in which neither the patient nor doctor know who has the drug and who has the placebo. neither the patient nor the medical staff treating the patient, know whether the patient is receiving the treatment or the placebo. If they did know, it could affect the way they report symptoms. Someone else prepares the treatments.
In a blind trialA clinical trial in which the patient does not know whether they are receiving the new treatment but their doctor does. the doctor knows which treatment the patient is receiving but the patient does not know. This kind of trial is used if it is important that doctors monitor certain harmful side-effects carefully.
An open-label trialA clinical trial in which both patient and doctor know if the patient is receiving the new treatment. may be used if there is no way to hide which treatment is the new medicine. It may also be used if there is no other treatment available and the patients are so ill they are likely to die without treatment.
Placebos, inactive versions of the drug, are also used to ensure that the drug is having an effect and that any changes are not due to the experimental trial process.
What can go wrong - Thalidomide
Thalidomide is a medical drug that caused unexpected and serious damage to unborn babies in the 1950s and 1960s. Thalidomide was developed as a sleeping pill, but it was also thought to be useful for easing morning sickness in pregnant women. Unfortunately, it had not been tested for use in this way.
Birth defects
By 1960 thalidomide was found to damage the development of unborn babies, especially if it had been taken in the first four to eight weeks of pregnancy. The drug led to the arms or legs of the babies being very short or incompletely formed. More than 10,000 babies were affected around the world. As a result of this disaster, thalidomide was banned. Drug testing was also made more rigorous than before.
Thalidomide today
Thalidomide is now used as a treatment for leprosy and bone cancer. Its use is heavily regulated, however, to prevent a repeat of the problems it caused in the last century.
Why medicines are expensive
Companies must pay for staff and equipment during lengthy research processes, which often result in no useful outcome. Even if it does complete clinical trials, every new medicine must go through a rigorous testing period in order to gather data to prove to the MHRA (Medicines and Healthcare products Regulatory Agency) that the medicine is safe and that it is effective. Only a very small percentage of potential new medicines complete the series of tests and trials needed before a medicine can be made available to the public.
