Labetalol in the treatment of epinephrine overdose.

A 31-year-old man being treated for asthma accidently received 3 mg SQ epinephrine. He began retching and vomiting and developed agitation and profuse diaphoresis. He was treated with 5 mg IV labetalol. His symptoms improved significantly, and he required no further treatment. Although he felt a transient increase in his respiratory effort shortly after administration of the drug, he did not develop wheezing or require additional therapy for bronchospasm. The beta-blocking effect of labetalol is greater than the alpha antagonism. The patient exhibited evidence of mild alpha stimulation due to incomplete blockade. This is consistent with previous studies in that labetalol tends to less completely antagonize the alpha effects of a mixed alpha/beta agonist, resulting in a net clinical picture of mild alpha agonism.