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From mice to men
Pharmaceutical companies carry out a series of clinical trials in humans to test each investigational drug for the potential to become a new medicine.
For all pharmaceutical companies the safety of its products is of vital importance. Therefore the journey from molecule to medicine involves a series of studies in both animals and humans to ensure that the potential medicine is as safe and effective as possible.
In March 2006, publicity in the UK drew attention to the clinical trial process. This article describes how GlaxoSmithKline approaches clinical trials and subsequently publishes the results for medicines that reach the marketplace.
Initially, studies on animals, tissues and cell culture are used to prove that a candidate medicine has the potential to be effective against a specific disease or condition in humans. Once all of the data have been analysed, the decision is made to progress to trials in humans.
Clinical trials are usually carried out by contract research organisations on behalf of pharmaceutical companies. The recruitment of volunteers is usually done by these companies with the involvement of the clinician responsible for the studies.
Volunteers are financially compensated for their time and inconvenience and the payments they receive are related to the duration of the study and the intensity of the procedures that they will experience. They are also given information that helps them fully to understand the risks and benefits of the study.
The first stage of the clinical trial programme involves so-called phase I trials with a small number of healthy volunteers. These trials study the safety of the drug and its interaction with the body. Specifically, the researchers will be looking for a medicine’s side effects and the way that the body deals with different doses of it.
Reassuringly, these initial studies, as with all clinical trials, are strictly regulated by the medical authorities of the countries in which they are carried out to ensure that the studies are ethical, unbiased and as safe as possible for the volunteers.
Phase I trials are often ‘double-blind’ - in other words neither the volunteers nor the doctors know who is getting the potential medicine or an identical but inactive ‘placebo’. This ensures that the participants do not influence the results based on the knowledge of who is receiving what.
Once the results of the phase I trials are known, Phase II studies enrol patients with the illness an investigational drug is designed to treat. These trials evaluate whether the drug is effective in treating an illness and seek to find the most effective dose. Again, as with all stages of the clinical trials process, the evaluation of the safety of the medicine continues.
If Phase II results have been encouraging, phase III trials, the largest part of a clinical development programme, go forward. Phase III trials are designed to provide the clear evidence of effectiveness and safety required by a country’s regulatory agencies that will approve the potential medicine and allow it to be marketed.
Phase III trials may also compare the new medicine with existing treatments for the disease or condition it treats.
Trials of a new medicine may continue even after it has been approved for marketing. Known as phase IV trials, they may further evaluate the longer-term side effects of the medicine or its effectiveness in different diseases.
Given the exploratory nature of clinical development, investigators often need to conduct trials of different designs to determine the potential of a potential medicine and its best use. This also includes looking at how a new medicine may interact with other medicines that could be used in combination to treat complex diseases, again with an emphasis on safety.
However, it’s worth remembering that no medicine is one hundred per cent safe and that there are occasionally trade-offs to be made between a medicine’s effectiveness and side effects.
Therefore, a pharmaceutical company performs a detailed analysis of its studies for submission to each country’s regulatory agencies as well as publishing the results of studies in medical journals and at scientific meetings.
Once approved for marketing, the agencies define prescribing information that doctors use to ensure the most appropriate use of the medicine. This prescribing information also helps doctors to decide if a medicine is appropriate for patients based on their symptoms, other medicines that they may be taking and so-called ‘contra-indications’ that may recommend that certain patients should not take a specific medicine.
GSK's commitment to openess
In 2004, GSK launched its Clinical Trial Register to provide transparent and open access to data from GSK-sponsored clinical trials. By the end of 2005, the Register contained results from 2,125 trials on over 40 of its marketed products.
At the time of the launch of the CTR, Tachi Yamada, former Chairman R&D at GSK said,
"The Register supplements our efforts to ease access to clinical-trial data for everyone interested in medical research and patient care".
GSK will continue to add data to the Register to ensure that researchers, healthcare professionals and the public has access to the clinical information that supports its products.
It’s reassuring to know that the medicine that you or your loved ones take to cure a disease or relieve the symptoms of a condition has been thoroughly tested to ensure that it is both as safe and effective as possible.
It’s also good to know that doctors have a range of innovative and effective medicines available plus the information they need to make the best decisions about treating patients.
