Factors influencing the degree and outcome of acute beta-blockers poisoning.

Since severe and fatal poisoning with beta-blockers due only to beta-receptor blockade is unlikely, a prospective and partly retrospective analysis of 67 patients with beta-blockers poisoning was done in five-year period in order to determine the factors influencing the degree and outcome of acute poisoning. According to pharmacological properties of drugs, the patients were divided in groups: group I--50 patients with propranolol, group II-A--10 patients with atenolol and group II-B--7 patients with metoprolol poisoning. Electrocardiogram (ECG), 24-h ECG monitoring, toxicological screening (determination of beta-blockers in blood, urine and lavage by high performance liquid chromatography) and biochemical analysis were performed in all patients. Significantly smaller number of patients with serious poisoning was observed in group II-B. Patient's age did not correlate with the degree of poisoning, but significant correlation was found between preexisting disease, ingested dose and the time elapsed before the treatment started. Analysis of pharmacological properties showed that membrane stabilizing activity and lipophilicity of the drug might be the important determinants of the toxicity, while the role of cardioselectivity was lost in an overdose.