By: Vallinadh Karamcheti
Abstract: Clinical trials are conducted to ensure the safety and efficacy of the drug. They are conducted on the human subjects. Hence the clinical trials are liable to many legal aspects. Clinical trials are conducted in four phases. (Phase I, Phase II, Phase III, & Phase IV). All the phases of the clinical trials should comply with several legal aspects, as life of a person may be at risk if anything goes wrong with the clinical trials. They should comply with the Schedule Y of Drugs and Cosmetics Act, 1940, Drugs and Cosmetics (II Amendment Rules) Rules 2005, Good Clinical Practices guidelines, 2001 etc. What are clinical trials?
Clinical trials are the tests conducted on human subjects to test the safety, efficacy, tolerability, and phamaco-kinetic properties of the drug. Why and how are they conducted?
Clinical trials are conducted in four phases
• Phase I trials are performed on a small group (normally 20-80) of normal healthy volunteers, and their aim is to check for safety (does the drug produce any potentially dangerous effects, for example on cardiovascular, respiratory, hepatic or renal function?), tolerability (does the drug produce any unpleasant symptoms, for example headache, nausea, drowsiness?) and pharmacokinetic properties (is the drug well absorbed? What is the time course of the plasma concentration? Is there evidence of cumulation or non-linear kinetics?). Phase I studies may also test for pharmacodynamic effects in volunteers (e.g. does a novel analgesic compound block experimentally induced pain in humans? How does the effect vary with dose?).
• Phase II studies are performed on groups of patients (normally 100-300) and are designed to test for efficacy in the clinical situation, and if this is confirmed, to establish the dose to be used in the definitive phase III study. Often, such studies will cover several distinct clinical disorders (e.g. depression, anxiety states and phobias) to identify the possible therapeutic indications for the new compound and the dose required. When new drug targets are being studied, it is not until these phase II trials are completed that the team finds out whether or not its initial hypothesis was correct, and lack of the expected efficacy is a common reason for failure.
• Phase III studies are the definitive double-blind randomised trials, commonly performed as multicentre trials on 1000-3000 patients, aimed at comparing the new drug with commonly used alternatives. These are extremely costly, difficult to organise, and often take years to complete, particularly if the treatment is designed to retard the progression of a chronic disease. It is not uncommon for a drug that seemed highly effective in the limited patient groups tested in phase II to look much less impressive under the more rigorous conditions of phase III trial Increasingly, phase III trials are being required to include a pharmacoeconomic analysis, such that not only clinical but also economic benefits of the new treatment are assessed. The whole process has to comply with an elaborate code known as Good Clinical Practice, covering every detail of the patient group, data collection methods, recording of information, statistical analysis and documentation.
At the end of phase III, the drug will be submitted to the relevant regulatory authority for licensing. The dossier required for this is a massive and detailed compilation of preclinical and clinical data. Evaluation by the regulatory authority normally takes a year or more and further delays often arise when aspects of the submission have to be clarified or more data are required. Eventually, about two-thirds of submissions gain marketing approval
•Phase IV studies comprise the obligatory post marketing surveillance designed to detect any rare or long-term adverse effects resulting from the use of the drug in a clinical setting in many thousands of patients. Such...