Clinical Trials: Availability, Volunteers, Drug Research

Author: Disabled World (DW)
Updated/Revised Date: 30 Dec 2025

Contents: Synopsis - Introduction - Main - Publications - Subtopics

Synopsis: Information, availability, and findings of federally and privately supported clinical trials conducted around the world.

Introduction

Clinical trials are defined as research studies that test how well new medical approaches work in people. Each study answers scientific questions and tries to find better ways to prevent, screen for, diagnose, or treat a disease. Clinical trials may also compare a new treatment to a treatment that is already available. Such prospective biomedical or behavioral research studies on human participants are designed to answer specific questions about biomedical or behavioral interventions, including new treatments (such as novel vaccines, drugs, dietary choices, dietary supplements, and medical devices) and known interventions that warrant further study and comparison.

Main Content

Clinical trials are conducted to allow safety and efficacy data to be collected for new drugs or devices. These trials can only take place once satisfactory information has been gathered on the quality of the non-clinical safety, and Health Authority/Ethics Committee approval is granted in the country where the trial is taking place.

During the clinical trial, the investigators: recruit patients with the predetermined characteristics, administer the treatment(s), and collect data on the patients' health for a defined period. These data include measurements like vital signs, amount of study drug in the blood, and whether the patient's health gets better or not. The researchers send the data to the trial sponsor, who then analyzes the pooled data using statistical tests.

The U.S. National Institutes of Health (NIH) organizes trials into five different types:

• Prevention trials: look for better ways to prevent disease in people who have never had the disease, or to prevent a disease from returning. These approaches may include medicines, vitamins, vaccines, minerals, or lifestyle changes.
• Screening trials: test the best way to detect certain diseases or health conditions. Diagnostic trials: conducted to find better tests or procedures for diagnosing a particular disease or condition.
• Treatment trials: test experimental treatments, new combinations of drugs, or new approaches to surgery or radiation therapy.
• Quality of life trials: explore ways to improve comfort and the quality of life for individuals with a chronic illness (a.k.a. Supportive Care trials).
• Compassionate use trials: provide experimental therapeutics before final FDA approval to patients whose options with other remedies have been unsuccessful. Usually, case by case approval must be granted by the FDA for such exceptions.

Clinical trials used in drug development are sometimes described by phase. In the U.S. these phases are defined by the Food and Drug Administration (FDA). Clinical trials involving new drugs are commonly classified into four phases:

• Each phase of the drug approval process is treated as a separate clinical trial.
• The drug-development process will normally proceed through all four phases over many years.
• If the drug successfully passes through Phases I, II, and III, it will usually be approved by the national regulatory authority for use in the general population.
• Phase IV are 'post-approval' studies.

Curated and edited by Ian C. Langtree, Founder & Editor-in-Chief, Disabled World. This section is maintained by the Disabled World editorial team.

Last updated: 30 Dec 2025