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cell culture

Growing cells under controlled conditions, generally outside of their natural environment.

Therapeutic

Healing. A therapeutic treatment is one that works to treat a disease.

Efficacy

How well the drug works

Placebo

A control that is used in drug trials. It looks exactly the same as the medicine under test but it does not contain the active ingredient.

Tissue

A group of cells in an organism that are specialised to work together to carry out a particular function.

Cancer

A mass of abnormal cells which keep multiplying in an uncontrolled way.

Developing medicines

To develop a new medicine it is important to understand how the human body works and how it is affected by a particular disease. A successful medicine treats hundreds of thousands or even millions of patients. It also makes money for the pharmaceutical company which in turn enables them to carry out research into more new medicines to treat more diseases. For any medicine to be successful it must be:

  • Effective
    it must prevent or cure the disease it is aimed at, or relieve the symptoms for the patient.
  • Safe
    it is very important that a medicine cures a problem without causing unacceptable side effects.
  • Stable
    it is important that the chemicals in the medicine can be used under normal conditions and be stored for some time.
  • Successfully absorbed and excreted by our bodies
    however good a medicine might be in theory, it is no use unless it can reach its target and then be removed from the body once it has done its work.

Research into a new medicine has to make sure that all these conditions are met. This is why it takes a very long time - up to 12 years - and a great deal of money - up to around £550 million - to bring a new medicine into the doctor's surgery.

Steps in developing a medicine

Ideas developed, disease targeted
Search for possible therapeutic compounds - this includes computer design of molecules and the screening of thousands of molecules which are already known or have been found in microorganisms, animals or plants
Cinchona tree

Cinchona tree - The bitter chemical made by the cinchona tree to protect itself from damage by pathogens became known as quinine and for many years it was the only effective treatment for malaria

yew tree

Yew tree - a chemical first found in the leaves of the yew tree has led to tamoxifen, one of the best known drugs in the battle against breast cancer.

Cone shell

Cone shell - Cone shells make a venom which they use to kill their prey, but some of the chemicals from the venom are being developed as effective pain killers.

Potential compounds synthesised in the lab
In vitro screening - testing the potential medicines on cell cultures, tissue cultures and isolated whole organs
Animal testing - the small number of molecules which have made it through the first stages are now tested on animals for more information about their likely safety and effectiveness.
Animal testing continues looking at the effect of longer term exposure to the medicine
Clinical testing on humans begins with phase I trials on a small number of healthy volunteers to start investigating the safety of the medicine in people.
Human phase II trials run with a small number of patients suffering from the target disease to decide the best dose to use, check it is safe and to start to investigate how well it works. Phase III trials continue this with a larger number of patients
If the scientists feel the medicine has passed all the trials, the company sends all the data to the international regulating bodies. If they are satisfied with the research the medicine will be granted a licence and can be prescribed by doctors for their patients to treat certain diseases
Once the medicine is on the market phase IV trials continue - the efficacy and safety of the medicine is monitored all the time the medicine is used. These long term trials mean that any unexpected side effects which only develop after the drug has been used for a long time, or which only affect a small group of people with a rare genetic makeup, can be picked up and dealt with.

Different types of clinical trials

When new medical treatments are being tested there are a number of ways the trials can be run. These include:

  • Randomised trials
    most drug trials are randomised after phase II. This means that patients are selected at random to get the experimental treatment or a comparator. The comparator may be a harmless pill with no action (a placebo) or the best available current treatment.
  • Open label trials
    both the researcher and the patient know what drug they are being given. Sometimes this is inevitable if, for example, you are comparing a medical treatment with physiotherapy or exercise.
Doctor.

© iStock photo.com

  • Blind trials
    the researcher knows if the patient is being given a trial drug or a placebo, but the patient does not - they are blind. The problem with this is that the researcher may give unconscious clues to the patient about whether they are getting the new treatment or not.
  • Double blind trial
    neither the researcher nor the patient know if the patient is being given the trial drug or not. Only a third person who is not involved in the research process has that information. This means that there is no chance of the researcher influencing the patient, consciously or not.