Adverse drug reaction monitoring--digitoxin overdosage in the elderly

Drug-related illness is an everlasting universal problem and also an important cause of admissions to hospitals. Adverse reactions are still grossly underreported by medical professions. Little information is available regarding the frequency or type of ADRs managed in hospitals. Since January 1997, we have taken part in a study, supported by the German Federal Institute for Drugs and Medical Device to improve the spontaneous drug information reporting system in Germany. Three German regionalized Departments of Clinical Pharmacology--Jena, Dresden, Rostock--serve as Pharmacovigilance Centers in collaboration with the Pharmacoepidemiology Research Group of the University of Munich. Since January 1997, the regional group in Jena has been monitoring the University Clinic of Internal Medicine for admissions caused by adverse drug reactions. All emergency cases and patients on intensive care units were checked for adverse drug reactions. We present our results, including clinical and demographic data, concerning intoxications and especially those involving digitoxin in 210 patients with ADR. Forty patients with digitoxin toxicity had an average age of 81 years (81.1+/-6.3), a low body weight (59.7+/-12.7 kg) and 3 out of 4 were women. 75% of all patients with digitoxin side effects had elevated serum digitoxin levels with concentrations higher than 25 microg/ml. The relatively high frequency of digitoxin intoxications in our hospital may reflect the advanced age and low body weight of patients. Patients received digitoxin regardless of age, weight and, sometimes, clinical indication. Physicians should be aware of drugs having a high risk when used in elderly patients. The use of digitoxin assays and keeping serum levels within or near the therapeutic range will diminish the incidence of overdoses.