Uppsala universitet
Hoppa över länkar
På svenska

Linné on line arrow Linnaeus and Pharmacy arrow Plants are important arrow Developing a new drug arrow Pharmacological tests

Pharmacological tests

Pharmacological tests are used when one wants to evaluate if a substance or plant extract is biologically active. There are many pharmacological tests and each one of them demonstrates various aspects that are important for the understanding of the mechanisms behind illnesses, their causes and cures. When people talk about pharmacological tests they often think about tests on animals, but in fact these form only a small part of all such tests. One can determine if a substance has an effect on isolated enzymes as well as human or animal cells by using a test tube. For instance, products for treating cancer are first examined in test tubes on cultivated cancer cells from tumours and only if they have a good effect are they then tested on other systems.

Unfortunately it isn’t possible to develop drugs without using any animal testing at all, since the absorption and decomposition as well as any damaging effects must be studied in a whole organism in order to give a correct picture. The various organs in the body influence the drug and are affected differently by the drug and this involves, among other things, the risk of missing damaging effects caused by the drug directly or indirectly via products of decomposition. On the other hand one can minimise the number of animals in drug development and ensure good conditions for those animals that are used. Ethical codes concerning laboratory animals are important in ensuring that animals are treated well.


Toxicological tests

To avoid harming human beings, various toxicological tests are made to detect possibly dangerous side effects. These can either be test tube experiments, for instance when cultivated human liver cells are tested for adverse effects from a certain substance, or animal experiments where, for example, tests are performed to try to establish effects on various organs.

First and foremost, test tube experiments are used to determine if the substance affects the cells from different human organs. It also possible to see if the substance damages the gene pool or could cause cancer. If the substance shows no dangerous effects in these tests, then further testing is carried out on animals.


Most drugs affect not only the body but are in turn affected by the body. The body’s organs break down the drug into various metabolites – these are the products of the degradation process which are chemically related to the drug. This means that the body is affected differently depending on how long the product remains in the body. The metabolites can also have medicinal effects. The study of how fast and in which ways a drug is both absorbed into, and excreted from the body, is called pharmacokinetics.

If you are given an injection, the medicine is injected directly into the bloodstream and the drug begins its work almost immediately. On the other hand if you take a pill, this has to first find its way down into the stomach and be dissolved before the body can absorb it through the mucous membrane of the stomach. For this reason it takes a while before the concentration of the drug is sufficiently high in the blood for it to have a medicinal effect. It takes about a quarter of an hour before the active ingredient of a headache pill gets into the bloodstream and can begin to fight the headache. Nevertheless you often feel better almost immediately after taking the pill. This is called a placebo effect – the effect of an expectation. You feel better just because you have taken the medicine and not because the medicine has begun to work. The effects of drugs are often compared to the effects of a placebo, e.g., sugar pills that contain no medically active substances.

Read More