Bioequivalence and Bioavailability Forum

Dear Sudhanshu,

This forum mostly deals with BA/BE trials, it may not be the best source of information for these questions.

❝ could you please tell me what is the difference between Phase IV studies

❝ and Post Marketing surveillance?

Phase IV studies are defined in the ICH E8 guideline. They are post-marketing studies. Post marketing surveillance would include phase IV studies + pharmacovigilance + any kind of surveillance requested by the regulatory authority approving the drug (such as risk-management plans etc.).

Regards
Ohlbe

Dear Sudhanshu!

❝ I also want to know what exactly the definition of 'Gold Standard' in

❝ clinical Trials.

A 'Gold Standard' in clinical trials should be considered a myth, although some designs are quite common in different phases. Although BE seems to be a quite simple kind of Phase I studies, the forum is full of discussions about appropriate designs...

Just some hints about another phase:
In Phase III a randomized, double-blind parallel design is the standard, but the number of treatment arms depends on

• the severity of the disease
  
• the availability of a standard treatment
  
• interim analyses
  
• ethical concerns
  
• etc.

Whilst it should be possible to run only two groups (new vs standard) in some life-threatening diseases (e.g., HIV, cancer), some others - especially if the difference from baseline is expected to be small - call for three arms (new vs standard vs placebo) in order to validate the study. For an entirely new treatment two arms (new vs placebo) would be the best choice.
If the disease is stable and the treatment effect is reversible after a washout (e.g., some types of asthma), a cross-over design would give higher power...

Every study should be designed by a specialist in close collaboration with an experienced biostatistician.