Adverse Events and Reactions: Etiology, Drug Interactions, Collection, and Reporting

There is an old but nonetheless true dictum in pharmacology: no drug has a single action. Unfortunately, multiple actions of therapeutic drugs are not always in the best interest of the patient. In addition to the primary therapeutic event for which a drug is prescribed, the likelihood exists for the emergence of concurrent or delayed, unwanted, and potentially harmful adverse events that may be due to other known pharmacologic or toxic events of a drug. Such reactions also may be attributed to some idiosyncrasies in certain individuals. Any active drug, therefore, may be a double-edged sword, doing good on one hand and perhaps harm on the other.