How Are Drugs Approved?


In the United States, drugs must be approved by the Food and Drug Administration (FDA) before they can be sold.  The FDA requires clinical trials to prove that the drugs are safe and effective, and to document risk factors and side effects.  Clinical trials also determine the appropriate treatment protocols – dosages, and the best ways to administer the drug.

Trials on human patients are usually preceded by animal studies, to better understand the risks and potential benefits of the treatment.

Before a human trial begins, it must be approved by an Institutional Review Board (IRB), which is responsible for ensuring the welfare and rights of trial participants.

There are four phases of clinical trials, and the entire process may take many years.

Phase I

The drug is administered to a small group of patients (from 20 to 100), to be sure that is is safe before it is tested on larger groups.

Phase II

The drug is administered to several hundred patients, to determine its effectiveness, and to continue to discover side-effects and risks.

Phase III

The drug is administered to several thousand patients.  The main goal at this stage is to test the drug on a wider range of patients, to learn things like how the drug interacts with other medications, or how it affects people who may have other medical conditions.  The dosages and ways to administer the drug are further refined.

After one or more successful Phase III trials, the FDA can approve the drug.  However, they may require a Phase IV trial, even after the drug is approved.

Phase IV

The drug is available for general use, either by prescription or over-the-counter.  Data is gathered from a large number of patients, to continue to look for side effects or risk factors.

What Gets Approved?

In the United States, the Food and Drug Administration (FDA) is responsible for approving drugs and certain other treatments, based on the results of clinical trials.  Other countries have similar agencies.

Data from drug trials is made available for peer review, so that other doctors and scientists can evaluate the results and submit comments as part of the FDA approval process.

The FDA has a difficult job balancing the risks and benefits of new drugs.  They don’t want to withhold potentially useful drugs, but they also don’t want to approve drugs that harm people.  In addition to the drugs being approved, they also consider other treatments that are already on the market.  For example, they may approve a drug with significant risks if there are no other alternatives available.  On the other hand, they may withhold approval for a dangerous drug if there are other drug with fewer risks that perform almost as well.

Who Conducts Clinical Trials

Trials may be conducted by hospitals, clinics, university researchers, or even private doctors.  A medical doctor must lead the trial, but nurses, statisticians, clerical staff and even students may be involved.

Trials can be funded by hospitals, universities, research foundations, government agencies, or pharmaceutical companies.

The FDA closely monitors all trials, to be sure that they are conducted properly.    Note that the FDA is a government agency; they don’t receive any funding from drug companies.

Further Reading

  1. What is a Clinical Trial?, ED Treatment Information Center.

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About Author

Lightning Science founder Robert Nicholson is a serial Internet entrepreneur with a passion for using science to improve life on earth.

He is also the founder of the ED Treatment Information Center, and an instructor in Computer Engineering at San Jose State University.

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