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Ritesh Mandal Dr.

    Clinical Research : Primer



All research studies done on humans are termed as Clinical Trials. The most commonly performed clinical trials evaluate new drugs, medical devices, biologics, or other interventions on patients in strictly scientifically controlled settings. The trial on humans are adequately guided and controlled by the regulatory authorities.
                     All Clinical trials need to be approved and carried out in compliance to the drug regulatory authority regulations of the respective countries where they are undertaken. The ICH GCP (Good Clinical Practices) guidelines forms the basis of all regulations and therefore all clinical trial conduct must comply as per guidelines laid down in ICH-GCP as well.
                     Clinical Trials are conducted in 4 stage modules or Phases (phase 1 to Phase 4). Before going into Humans for Clinical research, adequate data from Animal and Biologic studies (combined Pre-Clinical Studies) are sent to regulatory authorities to obtain approval for Clinical Trials.

Patient or Subject Safety is given paramount importance in the conduct of any clinical trial.

Before getting into further details, let me explain that these clinical research stages are designed to answer some basic questions  listed below:        

Phase 0: What are the effects of the sub-therapeutic doses of drugs on the human body?  [Phase zero study may not be applicable for all drugs, and it provides only a clue of pharmacokinetics/pharmacodynamics of the drug. The resultant data may provide vital information about first in human response to the drug]

Phase 1: What are the effects of the Drug/intervention on the human body?   What's the best route of administration? Find a safe dose? More...

Phase 2: Does the intervention have the intended effect on Subjects? How does the intervention affect the human body?

Phase 3: How does the new intervention (or new use of an intervention) compare to the standard practice?

Phase 4: What are the effects of long-term or novel uses of an approved intervention? e.g. Withdrawal of NSAID Rofecoxib (Vioxx ®) from market mostly due to its increased risk of cerebrovascular events. Other examples are Cerivastatin , Troglitazone.

Classification of Clinical Trials :

Based on outcome :

Treatment trials e.g. Proton Therapy for Stage I Non-Small Cell Lung Cancer  
Prevention trials e.g. Calcium preventing eclampsia in pregnancy.  
Screening & Early-detection trials e.g. Longitudinal CA-125 algorithm for the early detection of ovarian cancer in a low risk cohort of women  
Diagnostic trials e.g. Positron Emission Tomography in Detecting Testicle Cancer  
Quality-of-life/supportive care trials e.g. Chemotherapy patients receiving adjuvant drugs to reduce their nausea  
Genetics Trials e.g. Identify genes that affect susceptibility to obsessive-compulsive disorder (OCD).  

Based on trial design :

Clinical trials are mostly Randomized blinded trial based on the trial design, The other observational types are : Cohort Study, Cross-sectional study & Case-control study.

Randomized blinded study Two groups selected at random and the intervention is blinded  
Cohort study A group is followed over time  
Case-control study Two groups selected based on presence or absence of disease or condition  
Cross-sectional study A group examined at one point of time  

Randomized Controlled Clinical trial : A carefully and ethically designed experiment which includes the provision of adequate and appropriate controls by a process of randomization so that precisely framed questions can be answered.




Drug Discovered/ Identified / Created / 

Laboratory/ Pre clinical Testing


IND application filing with Regulatory Body


Phase 0


Phase 1


Phase 2


Phase 3

> File NDA or BLA with Regulatory Authority (e.g. FDA) > Marketing Approval Phase 4
          First in human - Safety   Safety   Safety and Dose   Safety and Efficacy          





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