Post Marketing Surveillance: Definition

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post marketing surveillancePost marketing surveillance is the monitoring of drugs and other medical products after they have been initially approved and introduced to the market. It is part of the science of pharmacovigilance, which is the study of, detection, assessment, and prevention of drug related problems such as side effects, adverse outcomes, or lack of positive effect.

In the United States, initial approval for a new drug is granted by the FDA (Food and Drug Administration) after phase I, II, and III trials are run. Because of this, post marketing surveillance is often referred to as phase IV trials. However, this is technically incorrect as a phase 4 trial can also be a well-controlled, randomized experiment; this is different from post-marketing surveillance, which is purely observational and non-experimental.

Components of Post Marketing Surveillance

Most of postmarketing surveillance involves testing for adverse reactions and monitoring/evaluating those which are already known. But that’s not all it is. It also involves other issues like:

  • Pediatric testing,
  • Formulating pediatric recommendations,
  • Dealing with off-label drug use,
  • Issues with orphan drugs (drugs developed to treat extremely rare diseases).

Methods Used in Postmarketing Surveillance

Postmarketing surveillance includes managing reporting systems where adverse effects reported by medical professionals and other professionals are logged. In addition, the surveillance includes:

  • Conducting surveys,
  • Spot checks by surveillance agencies such as the FDA,
  • Monitoring drug shortages or price jumps.

Since the data collected by postmarketing surveillance is on a much larger scale than the small numbers involved in initial drug trials, statistical analysis becomes crucial to make sense of the aggregate data and decide what reports are statistically significant and worth focusing on.


Vlahovic-Palcevski, Metzer. Postmarketing Surveillance. Handbook of Experimental Pharmacology 2011;205:339-51. Retrieved from on April 7, 2018

WHO Publications. Essential Medicine and Health Products: Regulation: Post Market Surveillance
retrieved from on April 7, 2018

Waning & Montagne. Pharmacoepidemiology: Principles and Practice. Chapter 8: Post-Market Surveillance
retrieved from on April 7, 2018

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