What are Drug Clinical Trials?

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  • Written By: H. Schonthal
  • Edited By: C. Wilborn
  • Last Modified Date: 19 December 2019
  • Copyright Protected:
    Conjecture Corporation
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In order for a new pharmaceutical treatment to be approved, its safety and effectiveness first must be established through a series of drug clinical trials. These trials are designed to test how well a new drug or vaccine works in humans after preliminary laboratory tests have shown promising results. Only after its safety and effectiveness have been proven in drug clinical trials does a new treatment become available for use by healthcare professionals and their patients.

Drug clinical trials are carried out according to specific protocols, or research plans. For each trial, there is a protocol that specifies the type of participant, drug doses and administration, testing methods, trial length, and the trial goals and outcome measures. These protocols serve as the basis for further studies and provide a framework for reporting results to the scientific community.


Investigations into new drug treatments generally occur in four phases. In a phase I trial, a new drug is tested in a relatively small group of 20 to 80 participants to determine both the dosage amount and any side effects of the drug. Phase II drug clinical trials evaluate the safety and effectiveness of the new treatment in a larger group, usually 100 to 300 people. In phase III trials, the test protocol is carried out in 1000 to 3000 subjects to gather formal data on outcome measures and to further study the drug's safety and effectiveness. Finally, phase IV trials provide additional information on a treatment's risks and benefits once the drug has already entered the market.

People volunteer to participate in drug clinical trials for a variety of reasons. Some join to gain access to experimental treatments that are not yet available to the public. For example, test subjects may include cancer patients who have been referred to a specific trial by their physician. Others join for the chance to be treated by specialists who are pioneering new treatments for a particular condition. Still others choose to volunteer as a way to contribute to the field of medical research.

Researchers are required to notify participants of the risks and benefits associated with the drug being tested. Before enrolling in a clinical trial, participants sign an "informed consent" form. This form indicates that they understand that the treatment is experimental, that there may be unknown risks associated with the drug, and that they can opt out of the study at any time. During the trial, participants are closely monitored by members of the research team. Participant identities are kept confidential at all times.

Drug clinical trials may be administered or sponsored by pharmaceutical companies, government agencies, or individual researchers. The trial itself may be carried out at in a hospital, university, or other setting. While clinical trials often require major travel and time commitments on the part of participants, they also provide the opportunity for new treatment for many patients.



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