Clinical toxicology of beta-blocker overdose in adults

Beta-blocker overdose is potentially harmful due to the strong blood pressure-lowering and heart rate-lowering effects. However, conflicting data exist as to their differential toxicity, single-substance exposures and the effect of co-exposure with additional antihypertensive medication. For this, a 10-year retrospective, explorative analysis of the Mainz Poison Center/Germany database with regard to circumstances of beta-blocker exposure, doses, symptoms and treatment was carried out. Analyses were restricted to adult patients with single-substance exposures and co-exposures with one additional antihypertensive substance. Written follow-up information was obtained in half the cases. A total of 2967 cases were analysed, of which 697 were single-substance exposures. Metoprolol was most frequently reported followed by bisoprolol, atenolol, propranolol and sotalol. Metoprolol showed a linear dose-symptom relationship, whereas propranolol and sotalol seemed to have a threshold dose beyond which symptoms aggravated. Symptoms did not differ substantially, except for more seizures being reported with propranolol, and more CNS depression/vomiting with sotalol. Activated charcoal was used in 38%, gastric lavage in 11%, temporary pacemaker in 3%, glucagon in 1%, intubation for respiratory insufficiency and cardiopulmonary resuscitation in 1% and 0.5%. All patients recovered. In 174 co-exposure cases, the distribution of poisoning severity and rate of worsening of symptoms was comparable with single-substance exposures except one patient deceased after bisoprolol and verapamil co-exposure. In adults with beta-blocker overdose, no significant differences in poisoning severity among beta-blockers were detected, and no fatalities were observed with single-substance exposures. Co-exposures with other antihypertensives, sedatives or alcohol should be carefully attended to as fatalities might occur.