Cardiovascular depression resulting from atenolol intoxication.

A case of massive atenolol ingestion leading to hypotension in association with PR and QRS interval prolongation on the electrocardiogram is presented. These clinical findings are identical to those attributed to the membrane-stabilizing activity of propranolol and other lipophilic beta-blockers. It is commonly believed that hydrophilic agents such as atenolol lack this activity. A review of the literature reveals that hydrophilic beta-blockers may have membrane-stabilizing activity, though much higher concentrations are required to produce this action in comparison with lipophilic agents. This case and a review of the literature provides a potential pathophysiological basis for atenolol-induced haemodynamic depression.