Healthy Human volunteers part of which clinical trial phases
Ans. is 'a' i.e., I CLINICAL TRAILSo Before a new drug comes to the market, it is extensively tested in animals and invitro studies for safety and efficacy. It the drug is found to be promising in these studies, an application called USD (Investigational New Drug) is filed with United States food and drug administration (FDA), which is main regulatory authority. If the permission is granted, then drug is tested in humans. This testing is called clinical trial. These are divided into four phases.Phase 1 or Human Pharmacology and safetyo The drug is tested in normal human volunteers,o As the drug is not tested in the patients, efficacy can not be determined.o This is mainly for toxicity (safety) and pharmacokinetic studies.o This is first in human study.o Number of subjects -20-40Phase 2 or Therapeutic exploration and dose rangingo This is first in patient studyo Both efficacy and safety can be determined.o This phase is tested in small number of patients :early phase - 20 - 200 patients (single blind)late phase -50 - 300 patients (double blind)o This may be blinded or open label study.Phase 3 or therapeutic confirmationo The drug is tested in large number of patient (500-300) at several centers to include patient with different genetic make up.o This is done to generalize the results of the study to variable genetic and ethnic group,o It is designed to minimise error in information gathered in phase 1 and 2.o Generally this are randomized doubled blind trials,o Both efficacy and safety are determined.o If the drug is found to be safe and effective in these trials, then another application is filed with FDA (New Drug Application or DNA) to market the drug,o If approval is granted, the drug is marketed.Phase 4 (Post - licensing phase field trial)o This is post marketing surveillance of a drug to know the rare adverse effects or those occuring with prolonged use of the drug,o Ethical clearance is not required.o Uncommon/ldiosyncrotic adverse effects, or those that occur only after long term use and unsuspected drug interactions are detected at this stage.o Further therapeutic trials involving special groups like children, elderly, pregnantdactating women, patients with renal/hepatic disease, etc. (which are generally excluded during clinical trials) may be undertaken at this stage.
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Clinical Trials