About Drug Development Process
When a new drug compound is discovered, it must go through extensive pre-clinical and laboratory research before it is tested on humans. Information from this research is submitted to regulatory agencies who decide whether the drug is approved for human use. This research is divided into phases.
Pre-clinical phase usually refers to research done before the drug is tested on humans – generally in-vitro and animal studies. Animal research helps set boundaries for safe use in human testing.
Phase 1 research looks at drug safety using a small number (usually less than 100) of healthy human volunteers. This type of research is designed to determine what happens to the drug in the human body and to look at what side effects it produces as dose levels are increased. Completing this phase can take several months. About 70% of experimental drugs pass this phase.
Once a drug is shown to be safe, it is studied for efficacy in Phase 2 research. This phase can take from several months to two years and can involve several hundred patients. This phase is sometimes divided into two sub-phases. Phase 2a focuses on dose-response, type of patient, frequency of dosing and other issues involved in safety and efficacy. Phase 2b looks at patients who have the disease or condition to be treated, diagnosed, or prevented, and usually represent the most rigorous demonstration of the drug’s efficacy. Phase 2 is the point at which a new drug is usually compared to an approved drug for the same condition. About 1/3 of the drugs that pass Phase 1 will successfully pass Phase 2.
In Phase 3, the drug is tested in several hundred to several thousand patients and can take several years to complete. This phase provides additional information about the drug’s effectiveness, benefits, and the range of possible adverse reactions. Phase 3b can also be done to supplement or complete earlier research (quality of life, marketing, etc.) or may look at a new type of research to be done after regulatory submission but before marketing approval. It is usually at the completion of Phase 3 that a company can request approval to market the drug. About 70% of the drugs that pass Phase 2 make it through Phase 3.
Post-Marketing Phase research can also be done to compare a drug with other drugs already in the market, to monitor the long-term effectiveness and impact on a person’s quality of life, and to determine the cost-effectiveness of a drug therapy to other traditional and new therapies.