How are new drugs developed?

Here is a brief tutorial on the multi-year process by which pharmaceutical research brings new drugs to your local pharmacy. Most drugs are studied in animals before they are tested in humans. Each drug must then progress through the following series of research studies in humans before the FDA can approve it for use.

Phase I studies are typically conducted with healthy volunteers. The drug is tested in a small group of 20-80 people while researchers observe side effects, judge the safety of the drug and determine safe dosage ranges.

Phase II studies are conducted in a larger group of people who have the symptoms or illness that the drug is designed to treat, such as Parkinson’s disease. The goal of Phase II research is to evaluate the drug’s effectiveness as well as to gather more information about safety and tolerability.

Phase III studies are conducted with a much larger group of at least 1,000 people with a particular disease. In addition to testing the drug’s effectiveness and cataloging possible adverse effects, Phase III testing seeks to compare the drug to other similar approved drugs or to placebo (also known as a sugar pill or dummy pill).

The two most important characteristics of a Phase III trial are:

  1. Randomization of subjects to receive the experimental drug or placebo. Randomization means that study participants are assigned to a treatment group using a method based on chance; it is meant to minimize the differences between groups so that study results will be unbiased and reliable. If more than one dose of a drug is being evaluated, more subjects are needed to give the study enough statistical power to reach a valid conclusion about the drug’s effect on the disease being observed.
  2. Double-blind, which means that neither patient nor investigator knows which drug a patient is taking. This is another way to prevent observer bias in evaluating the effect of the drug.

Once a drug has successfully completed Phases I, II and III testing, it may be submitted to the FDA for approval. Once approved, the medication can be prescribed by physicians and other licensed health care providers.

Phase IV studies test the new, approved drug for additional benefits that may not have been studied in earlier phases. Phase IV studies also gather information regarding long term use and safety of the drug.

The entire process of bringing a new medication to the pharmacy can take up to ten years from the time that it is tested in a laboratory to the time that the doctor prescribes the drug for a person with disease.

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Understanding Research

Medical content reviewed by: Nina Browner, MD—Medical Director of the NPF Center of Excellence at the University of North Carolina at Chapel Hill in North Carolina and by Fernando Pagan, MD—Medical Director of the NPF Center of Excellence at Georgetown University Hospital in Washington, D.C.

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