Clinical trials are the experimental or observational research performed on human subjects meant to discover specific details regarding biomedical or behavioral interventions of an investigational medicinal product. In order to obtain marketing approval for any new drug or pharmaceutical medicinal product in the USA, EU, Canada, and most of the countries around the globe, a wide range of appropriate pharmacology and toxicology testing in humans with various phases needs to be conducted involving both patients as well as healthy subjects, these are termed as CLINICAL TRIALS. Clinical trials are also known as Interventional studies.
Clinical research involving worldwide clinical trials for new drugs or investigational medicinal products is divided into 4 phases of a clinical trial:
Phase 1 Clinical Trials:
Area of study: Human pharmacology
Duration of study: few months to 1 year
No. of subjects: 20 to 80
Type of subjects: Healthy volunteers
Trial design: Simple and open-label clinical trials/open-label studies
Phase 1 clinical trials are the foremost stages in determining the safety profile of drug effects in humans. They are designed mainly to find the maximum tolerated dose and the pathways. The major objective of phase 1 clinical trials are meant to examine the absorption, distribution, metabolism, and excretion (also known as ADME studies) as well as safety and toxicity.
Phase 2 Clinical Trials:
Area of study: safety & efficacy
Duration of study: few months to 2 years
No. of subjects: 100 to 300
Type of subjects: Patients
Trial design: Double-blinded clinical trials
Phase 2 clinical trials are usually performed in patients suffering from the disease for which the drug was originally developed. Phase 2 clinical trials are carried out for analyzing the efficacy and safety profiles of the medicinal product. The major objective is to find out the minimal effective dose that encloses efficacy with the minimum of AEs.
Phase 3 Clinical Trials:
Area of study: Risk-benefit ratio
Duration of study: 3 to 4 years
No. of subjects: 300 to 3000
Type of subjects: Special treatment groups (geriatrics/pediatrics/pregnant women/lactating mothers).
Trial design: Randomized-controlled clinical trials
Phase 3 clinical trials are usually the key (the old term is “pivotal”) studies to be submitted for regulatory approval, and they are incorporated in the NDA submission or “MA dossier.” Whereas Phase 3 clinical trials generally focus on pharmacoeconomic or risk evaluation issues as well as cost-effectiveness and studies against competitor drugs. Mostly astonishing or unexpected outcomes are seen in this phase.
Phase 4 Clinical Trials:
Area of study: Risk Evaluation and Mitigation Strategies (REMS)
Duration of study: minimum 2 years
No. of subjects: 10,000 to lakhs
Type of subjects: patients
Trial design: Variable (ranging from small open-label trials to massive, multicenter, double-blind clinical trials)
Phase 4 clinical trials are post-marketing trials or pharmacoeconomic studies meant to provide head-on comparisons with competitor drugs. Phase 4 clinical trials are conducted for specific safety reasons to investigate an AE or a signal that has unexpectedly occurred after marketing. These may be classical clinical trials or observational or epidemiologic studies performed over larger population databases.
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