Drug Development Process

HOW NEW DRUGS ARE DEVELOPED

Bringing a new drug to market involves a series of research stages and regulatory approvals. In total, the average new drug takes about 10 - 15 years to develop from discovery to approval for widespread marketing.

The Discovery stage
The work at this stage is mostly conducted in a laboratory and may take several years to yield results. It involves identifying target molecules or processes responsible for a particular application, then searching for compounds that might act against those targets. Once a potential compound is found, it is modified many times over to improve its drug properties. Tests are done in cellular and animal models to learn more about the compound's mechanisms of action against a particular application. If these experiments are successful, the compound moves into preclinical testing.

Preclinical Testing
This is where a potential drug is tested for its safety and effectiveness in an appropriate animal model. The results from preclinical research determine whether there is sufficient potential for a drug to proceed to testing in human clinical trials. Preclinical testing commonly takes one to three years to complete. Only one in 1000 compounds that enter preclinical testing makes it to human testing.

Investigational New Drug (IND) Application
Before a new drug can enter human trials, the company must usually file an Investigational New Drug (IND) application with the relevant authorities. In the U.S., INDs are filed with the Food and Drug Administration (FDA), while in Canada the Health Protection Branch (HPB) of Health Canada has jurisdiction. Once the relevant health authorities have reviewed and approved a company's application, a process that usually takes at least one month, the drug may enter the first phase of human trials. All human research must then be approved by the ethics committee of the institution in which the study is conducted.

Clinical Trials
A clinical trial is a research study in human volunteers to answer specific health questions. Carefully conducted clinical trials are the fastest and safest way to find treatments that work in people and ways to improve health. There are three phases in the typical clinical trials process. A new IND has to be approved before an investigational drug can move from one phase to the next.

Phase I Studies
Phase I trials involve a small number of healthy volunteers and typically last one year or less. The purpose of this phase of testing is to determine the metabolism and pharmacologic actions of the drug in humans, the side effects associated with increasing doses, means of administration, determine a safe dosage range, and to gain early evidence of effectiveness. These studies provide the first glimpse of the drug's tolerability, and the human safety profile-sometimes markedly different from that seen in animals. One out of five drugs that enter Phase I receive approval for market distribution.

Phase II Studies
Phase II trials, which usually last one to three years, are designed to identify the dose and dosage frequency, and further evaluate the drug's safety and effectiveness for a particular indication in patients. These studies often involve a larger number of patients.

Phase III Studies
If a drug shows encouraging signs of efficacy and proves to be safe in patients, it may enter important Phase III trials. In this phase, the drug is tested in a larger number of patients to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely. Phase III trials typically involve a larger group of patients and are monitored by physicians. Two out of three drugs that enter Phase III receive approval for market distribution.

Phase IV Studies
Post marketing studies delineate additional information including the drug's risks, benefits, and optimal use. This study is used to gain experience and monitor safety with a drug in large numbers of patients more closely resembling real-life conditions. Once a drug is available on the market, many patients who use it do not meet the strict inclusion criteria of the Phase III trials, and are less likely to use it as prescribed.

New Drug Application
Following the completion of Phase III clinical trials, a company analyzes all the data and if the data successfully demonstrates both safety and effectiveness files an NDA with the authorities in each country where it wants permission to market the drug. The NDA contains all the scientific information that the company has gathered.

Approval for a new drug to be made widely available to the health care market typically takes about 12 - 18 months. The authorities will review research data running to many thousands of pages. They will also weigh up the need for a new drug to treat the particular application. A drug may qualify for fast-track review if it is designed to treat a life-threatening disease for which there are few alternative therapies. Once the authorities approve the NDA, the new medicine becomes available for physicians to prescribe.

Discovering and developing safe and effective new drugs are a long, difficult, and expensive process, but once approved provides many benefits.