Definition of events associated with drugs: regulatory perspectives.

Drug regulations in the United States require that all clinical events reported associated with a marketed drug be collected by the manufacturer and provided to the regulatory agency. In the clinical setting, many factors determine (a) the likelihood of an event being detected, (b) the attribution of the event to the drug, and (c) the actual spontaneous reporting of the drug event association to the manufacturer, regulator or to the literature. In formal postmarketing trials to collect information on events occurring in drug exposed patients, the events detected are greatly determined by characteristics of the trial design. The further analysis of events suspected to be adverse drug effects is described. Once an adverse effect is hypothesized, a number of factors will determine whether it can be further studied in a meaningful, cost effective way.