Phases of clinical research

Clinical research for development of new drugs and other therapies, tests, etc. goes through a process called phases.

Hunger Disease Clinical Research in Famine Performed in the Warsaw Ghetto in 1942

Preclinical research

Before going to the stage of clinical trials, researchers do what are called preclinical trials, which may include animal studies, in vitro and in vivo studies but no human subjects. The purpose of this phase is to understand about the preliminary safety of the drug or device. Preclinical research deals with the basic questions about a drug’s safety. However, it is not a substitute for studies of ways the drug will interact with the human body.

Clinical research

“Clinical research” refers to studies, or trials, that are done in people.

Drug development

As the developers design the clinical study, they will consider what they want to accomplish for each of the different Clinical Research Phases and begin the Investigational New Drug Process (IND), a process they must go through before clinical research begins.

The Investigational New Drug Process

Stanford School of Medicine Center for Clinical Sciences Research

Drug developers, or sponsors, must submit an Investigational New Drug (IND) application to FDA before beginning clinical research.

In the IND application, developers must include:

• Animal study data and toxicity (side effects that cause great harm) data
• Manufacturing information
• Clinical protocols (study plans) for studies to be conducted
• Data from any prior human research
• Information about the investigator

Phases

All new drugs and therapies go through the following 4 - 5 phases(including phase 0).

Although most drugs go through phases 1-4 after preclinical trials, there is another less often used phase called phase 0 which is designed to help understand the drugs Pharmacokinetics; particularly oral bioavailability and half-life of the drug, which is usually done at mall, subtherapeutic doses with about 10 people. However, this phase 0 is often skipped for Phase I.

Phase 1

• Study Participants: 20 to 100 healthy volunteers or people with the disease/condition.
• Length of Study: Several months
• Purpose: Safety and dosage

Approximately 70% of drugs move to the next phase

Phase 2

• Study Participants: Up to several hundred people with the disease/condition.
• Length of Study: Several months to 2 years
• Purpose: Efficacy and side effects

Approximately 33% of drugs move to the next phase

Phase 3

• Study Participants: 300 to 3,000 volunteers who have the disease or condition
• Length of Study: 1 to 4 years
• Purpose: Efficacy and monitoring of adverse reactions

Approximately 25-30% of drugs move to the next phase

Phase 4

Study Participants: Several thousand volunteers who have the disease/condition Purpose: Safety and efficacy

Cost

The overall cost of bring a new drug to the market in the West can be over a billion dollars.

Phases of clinical research Resources
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