- The World Health Organisation (WHO) defines PhV as the science and activities relating to the detection, monitoring, assessment, understanding and prevention of adverse effects or any other drug related problems.
- Information collected during the pre-marketing phase of drug development might not detect rare Adverse Drug Reactions (ADRs).
- The use of a drug during a clinical trial is under controlled conditions, also, limited and selected numbers of patients are enrolled in the clinical trials.
- Drug use in special situations and population or drug interactions may not be studied. Therefore, the post-marketing surveillance of drugs is important.
- Spontaneous ADR reporting, during post-marketing surveillance, has shown to detect AE signals resulting from drug use in the population.
- The withdrawal from the market of certain medicines has focused attention on PhV approaches.