Drug Development

In the past, drugs were found by trial and error. Now they’re developed primarily by systematic scientific research. The Food and Drug Administration (FDA) carefully monitors new drug development, which can take many years to complete.

Only after reviewing extensive animal studies and data on the safety and effectiveness of the proposed drug will the FDA approve an application for an investigational new drug (IND).

Phases of new drug development

When the Food and Drug Administration (FDA) approves the application for an investigational new drug, the drug must undergo clinical evaluation involving human subjects. This clinical evaluation is divided into four phases:

Phase I

The drug is tested on healthy volunteers in phase I.

Phase II

Phase II involves trials with people who have the disease for which the drug is thought to be effective.

Phase III

Large numbers of patients in medical research centers receive the drug in phase III. This larger sampling provides information about infrequent or rare adverse effects. The FDA will approve a new drug application if phase III studies are satisfactory.

Phase IV

Phase IV is voluntary and involves postmarket surveillance of the drug’s therapeutic effects at the completion of phase III. The pharmaceutical company receives reports from doctors and other health care professionals about the therapeutic results and adverse effects of the drug. Some medications, for example, have been found to be toxic and have been removed from the market after their initial release.

Exceptions to the rule

Although most INDs undergo all four phases of clinical evaluation mandated by the FDA, some can receive expedited approval. For example, because of the public health threat posed by acquired immunodeficiency syndrome (AIDS), the FDA and drug companies have agreed to shorten the IND approval process for drugs to treat the disease. This allows doctors to give qualified AIDS patients “treatment INDs,” which aren’t yet approved by the FDA.

Sponsors of drugs that reach phase II or III clinical trials can apply for FDA approval of treatment IND status. When the IND is approved, the sponsor supplies the drug to doctors whose patients meet appropriate criteria.

Despite the extensive testing and development that all drugs go through, serious adverse reactions may occasionally occur, even though they weren’t discovered during clinical trials. It’s also possible that drug interactions aren’t discovered until after clinical trials have concluded and the drug has been approved. The FDA has procedures in place for reporting adverse events and other problems to help track the safety of drugs.