Rilevanza clinica e aspetti medico-legali delle interazioni tra farmaci

Drug-drug interactions (DDIs) are an important issue of clinical pharmacology. A drug interaction occurs when the amount or the action of a drug is altered by the administration of another drug or multiple drugs. The result of a DDI can be the onset of an adverse drug reaction (ADR), the lack or the reduction of efficacy or the increase of a pharmacological effect. Apart from pharmaceutical interactions, DDIs are generally classified as pharmacokinetic or pharmacodynamic, according to the underlying mechanism. The majority of known DDIs involve the drug metabolism. The main risk factors for DDIs are age, polypharmacy, self-medication, concomitant diseases, narrow therapeutic range and dosage. In the literature most of the studies on DDIs focused on potential interactions and most data about the epidemiology of actual DDIs are related to the out-inpatient settings with different incidences. In general the incidence of actual DDIs is lower than that of potential ones, however DDIs represent a significant proportion of ADRs, since the absolute number of patients involved is high. The use of specific suggestions and recommendations could be effective in the reduction of ADRs from DDIs.