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Understanding how treatments are developed and tested can help you be more informed. Appreciating that there is often some risk of side effects with most medicines and medical procedures can also be helpful. Knowing this enables you to ask your health professional questions that will help you understand what to expect from your treatment, and to take a more active role in your treatment decisions.

How are medicines developed?

Typically, a medicine dispensed from your pharmacy or hospital will be the one medicine, out of possibly several hundred compounds that were investigated, that showed a benefit to patients and made it through the various hurdles to become a marketed medicine.

To develop and be able to sell a new medicine usually takes a pharmaceutical company 10 to 15 years (and can cost hundreds of millions of dollars). This is in part because of the time spent testing the many other possible compounds that are not as successful as first thought at helping the disease or pose too high a risk in regard to potential side effects.

The development process of a medicine usually involves a pharmaceutical company, which owns the license to the medicine and funds the research and development. This process takes place in hospitals and clinics, often in several countries. Professional medical journals review and report the results. Governments and regulatory bodies (Medsafe and Pharmac in New Zealand) decide whether the medicine's use will be permitted, how much the patient will have to pay for it and whether or not it will be subsidised.

It is usual for the company that successfully gets a medicine onto the market to have it patented for five, 10 or more years to prevent other companies copying it. This allows the company to recoup its costs and make a profit selling the medicine. After this period, the medicine comes "off patent" and other companies may make their own versions (generic medicines), which can sell at a lower price.

The main stages of medicine development and approval

A possible drug molecule is identified by studying its effects in simulated studies (eg, in laboratory tests) and studies performed to ensure its safety (lack of toxicity). If the signs are still promising after several years' laboratory testing, "clinical trials" - organised studies in humans that test the doses and the usefulness of the drug - are then carried out. Throughout these clinical trial phases, the patients are monitored for side effects on a continuous basis to ensure the benefits of the medicine outweigh the risk to the patient.

• Phase I clinical trial (first time in humans): undertaken in healthy volunteers and determines the criteria for safe and effective use of the therapy - what dose range is safe and what side effects are there?
• Phase II clinical trial (early studies in patients): uses relatively small groups of patients to establish whether the therapy is effective at treating the disease or condition, and what are the optimal doses.
• Phase III clinical trial (comparative trial): larger numbers of patients are studied to compare the new medicine with established therapies and/or placebo (dummy treatments).

If serious problems are reported during phases I-III, the drug is withdrawn from study. A treatment may become available to patients at this point if all the trials have gone well and the country's medicines registration body (Medsafe in New Zealand) has approved its use for specific condition(s) and/or in specific groups of patients. It will consider what benefits it has over older (and maybe cheaper) treatments and what side effects are associated with the new treatment - no medicine treatments (old or new) are completely free of side effect risks.

• Post-marketing surveillance: after the launch of a medicine onto the market, surveillance for safety is monitored and any unpredictable or rare problems that arise among patients receiving it are reported. (Such problems can only be detected when the medicine is in general use by a large number of people over a long period of time.) The monitoring is carried out by the companies who make the medicines and, in New Zealand, by the Centre for Adverse Reactions Monitoring (CARM) in Dunedin.

If, through this surveillance, serious problems are reported, a decision will be made as to whether the medicine should be withdrawn or its use continued, but with special warnings.

Original material provided by everybody and reviewed March 2006.