(The Gist of Science Reporter) What Are Clinical Trials?
(GIST OF SCIENCE REPORTER) What Are Clinical Trials?
What Are Clinical Trials?
Development of drugs is a lengthy, complex and expensive process, full of failures and risks. The journey of a drug candidate from its discovery to the market requires about a decade and currently costs about 2.5 billion US$. This involves exhaustive studies in the laboratory, on experimental animals, and finally on human subjects that constitute the clinical trials. Only companies with huge resources can, therefore, undertake the endeavour.
The US Food and Drug Administration (FDA) and similar agencies in other countries lay down norms for the conduct of clinical trials of drugs, scrutinize them and once satisfied, approve their marketing. The Drug Controller General of India (DCGI) under the Ministry of Health and Family Welfare, approves licenses of drugs in India. In order to conduct clinical trials, companies in the USA are required to file Investigational New Drug application (IND) listing all details of the drug including its structure, investigations in the laboratory and on experimental animals showing its efficacy and safety. The FDA model, which is widely followed by drug regulatory agencies in most other countries, has three major phases of clinical trials.
In phase I, studies are done on a small number (< 100) of healthy volunteers in order to primarily assess the safety of the drug candidate. The studies also examine how the human body processes the drug (pharmacokinetics) and the impact of the drug on various body functions (pharmacodynamics). In addition, assessment of safe drug dosages and side effects, if any, are also made.
In phase II, studies are conducted on larger cohorts (100-500) of patient volunteers. Effect of the drug candidate is compared with other available drugs for the treatment of the disease as well as placebo (placebo is a substance that is designed to possess no therapeutic value).
Optimization of drug dosage and schedule of administration as well as investigation of short-term side effects on patient volunteers are undertaken.
In phase III, large numbers of patient volunteers (1,000-5,000) are included from across trial sites around the world. Fine details of efficacy safety of the drug in patients and overall risk-benefit ratios are examined. Some studies continue after a drug is marketed. Those that delineate risks, benefits and optimal use after making the drug available in the market constitute phase IV.