Phase IV trial is also known as post-marketing trial, or informally as a confirmatory trial.
Phase IV trials include a drug’s health surveillance (pharmacovigilance) and continuing clinical assistance until it gains clearance to be marketed.
Health surveillance is intended to track any unusual or long-term adverse effects over a significantly wide number of patients and longer duration than was feasible during clinical trials in Phase I-III.
These reports collect detailed knowledge on side-effects and health, long-term costs and benefits and/or how well the drug performs when commonly used.
One aspect of this work is a non-interventional analysis (NIS) designed to evaluate the health, tolerability, and effectiveness in clinical practice of a treatment.
These studies may be required by regulatory authorities or may be undertaken by the sponsoring company for competitive (finding a new market for the drug) or other reasons (for example, the drug may not have been tested for the interactions with other drugs, or on certain population groups such as pregnant women, who are doubtful to subject themselves to trials).
Phase IV may also include drug use studies (DUSS) that tell us how a drug is being marketed and actually prescribed within a population.
Finally, there is the registry or a prospective observational study of the patients with a common condition or risk that can result in an accurate assessment of clinical practice, patient, and comparative outcomes
