Drug repurposing
Drug repurposing investigates whether an existing drug can treat a different disease, serve a new use, or benefit a different patient group.
Drug target: A molecule in the body that a drug binds or alters to produce an effect. Known targets can reveal diseases a drug might affect beyond its original indication.
Sildenafil: A phosphodiesterase-5 inhibitor used to treat erectile dysfunction and pulmonary arterial hypertension. Its development for erectile dysfunction followed investigation of an unexpected effect observed during angina trials.
De novo drug discovery: The development of a new medicine from the identification of a target or candidate through preclinical and clinical testing. Unlike repurposing, it begins without an existing drug whose properties can be reused.
Drug repurposing clinical trial: A clinical study testing an existing drug for a disease, use, or patient group not previously established for it. Trials test whether a promising repurposing hypothesis produces meaningful benefits in people.
Drug repurposing failure: The failure of a proposed new use for an existing drug to show sufficient efficacy, safety, or feasibility. Biological plausibility and early signals often do not translate into useful clinical outcomes.
Phenotypic screening: A drug-discovery method that tests compounds for effects on cells or organisms without requiring a predefined molecular target. It can uncover new uses through observed disease-related effects rather than target hypotheses.
Thalidomide: A drug associated with severe birth defects that is used under strict controls to treat multiple myeloma and other conditions. Its later use in multiple myeloma exemplifies repurposing after its biological effects were reconsidered.
Drug development: The process of discovering, testing, and bringing medicines to patients. Repurposing is one route within drug development, with a candidate compound already in hand.
Drug safety: The assessment and monitoring of harmful effects associated with medicines. Prior exposure supplies safety information, but a new dose or population can introduce different risks.
Publication bias: The selective publication of research findings according to their direction, strength, or statistical significance. Unreported negative repurposing studies can make candidate drugs appear more promising than the evidence warrants.