Recognition, reporting and evaluation of adverse drug reactions

Adverse drug reactions (ADRs) occur in about 5% of drug-treated patients. H ospital admissions are caused by ADRs in 5% of patients and roughly 2% of h ospitalized patients will experience an ADR. The economic burden of ADRs ca n only be estimated. Type A reactions can be explained by the pharmacological action of the drug s, and are preventable in many cases. However, Type B reactions involving t he immune system and/or idiosyncratic reactions occur rarely and most of th em are not fully understood. Genotyping represents an elegant method to exp lain the presence of abnormal enzyme activities and allows prediction of ad verse drug effects in individual cases. Typical time frames have been ident ified for the occurrence of hypersensitivity reactions, although definite c ausality assessment is often impeded due to the absence or unavailability o f specific laboratory tests and the impossibility of rechallenge. Diagnosis of an ADR is often difficult due to comorbidity and polypharmacy, thus cau sality assessment of often divergent even between specialists. In Germany, ADRs are reported preferably to the manufacturer of the suspico us drug and then collected and evaluated at the Bundesinstitut fur Arzneimi ttel und Medizinprodukte, BfArM. However, total number and quality of repor ted ADRs could be improved.