Phase IV Clinical Trial
Studies conducted after regulatory approval to monitor long-term safety, detect rare adverse events, and evaluate real-world effectiveness in broader patient populations. Regulatory agencies may require Phase IV studies as a condition of approval, particularly for drugs with accelerated or conditional approval.
Technical Context
Phase IV studies serve multiple purposes: detecting rare adverse events (those occurring in <1:1,000-10,000 patients may not be captured in Phase III samples); evaluating long-term safety over years of use; comparing effectiveness against other treatments in real-world practice; studying use in special populations (elderly, paediatric, renal/hepatic impairment, pregnancy); and investigating new potential indications. Regulatory authorities can mandate Phase IV studies as post-marketing requirements (PMRs) or commitments (PMCs). For GLP-1 RAs, cardiovascular outcomes trials (CVOTs) serve as both Phase IV safety studies and efficacy trials for cardiovascular benefit. The SELECT trial (semaglutide) demonstrated cardiovascular benefit in patients with obesity without diabetes, expanding the evidence base beyond glucose control.