Getting New Drugs on the Market - Phases of Clinical Trials

The phases of a clinical trial identify how advanced the development of a new drug therapy or vaccine is and how far it may still need to go before gaining Food and Drug Administration (FDA) approval for distribution. Each phase is significant in the process of drug, vaccine, or medical device development.

An investigational new drug or IND application must be filed with the FDA when researchers want to study a drug or vaccine in humans. Researchers must show that the drug being researched appears to be safe to test with humans.

The goal is to get a drug or vaccine approved by the FDA. When laboratory research shows there is evidence that a new drug or vaccine may improve patient care, researchers present pre-clinical data to the FDA. This data includes manufacturing information and the plan for clinical research to the FDA to seek approval to proceed with clinical trials on humans. 

Four Phases of Clinical Trials

There are several phases to clinical trials. 

Phase 0

Researchers provide a new drug or treatment to a very small number of people—typically between 10 and 15 participants—to see how it affects the human body. If the results don't match what the researchers had expected, they will retreat to the lab to determine whether they should continue the trial.

Phase 1

Phase 1 trials test the safety and dosage for a new treatment. A slightly larger group of people (somewhere between 15 and 80) receives a graduated dosage in which some participants get a very low dose, while others get a higher dose to discover the point at which undesirable side effects occur. This process also helps determine what dose is effective with limited side effects. If researchers find the treatment is safe, they can move on to Phase 2.  

Phase 2

An even larger group of people (usually over 100) who are living with the condition that the treatment is intended to address will receive the dose found to be safe in Phase 1. Researchers observe them carefully to watch the effects. Generally, those who participate in phase 2 trials get divided into a control group that receives either a placebo or the current standard treatment for the condition or receives the experimental drug or vaccine. 

Sometimes, a drug is tested in combination with other treatments. If the treatment works in this group without unacceptable side effects, the research proceeds to Phase 3.

Phase 3

When a drug is in a phase 3 trial, it usually gets tested on several thousand patients with the condition or disease it is intended to treat. Phase 3 drug trials will take one to four years, and because they take a much more extended period of time to study its more likely to reveal long-term side effects than the earlier phases.

Researchers will measure the effectiveness of the new drug against the current standard of care. The goal here is to demonstrate that the new treatment is at least as safe and effective as current treatments, if not better. 

Patients are randomly allocated to receive either the current standard of care for their condition or the new treatment that is being tested. In phase 3, they usually use a double-blind study. Neither the patient nor the researcher knows which group receives the new drug being tested or the existing standard. Researchers get an unbiased view of the side effects and benefits of the drug being tested.

The trial will stop if there are severe side effects or if one group displays better results than the other. Successful Phase 3 trials are usually necessary for FDA approval of new treatments.

Phase 4

Phase 4 is referred to as post-marketing surveillance. In this phase, an FDA approved drug or vaccine continues to get studied on hundreds of thousands of people further to identify any rare or previously unknown side effects and monitor the treatment's effectiveness.

The clinical trial phases carefully follow a sequence to determine whether new clinical treatments or medical devices are safe, effective, and as good or better than existing treatments. These phases will also determine whether producing the treatment is feasible, meaning it is not only possible but practical, as well.

These clinical trials are essential for discovering new treatments for diseases.  Better medications to treat conditions offer better outcomes. Vaccines, on the other hand, can prevent an illness from occurring in the first place.  

The research and development of new drug therapies benefit both humans and animals. The many advances in the past few decades have directly improved the quality of life so we can enjoy a longer, healthier life.