Epinephrine and phenylephrine increase cardiorespiratory toxicity of intravenously administered bupivacaine in rats

We studied the effects of epinephrine and phenylephrine on the cardiorespiratory toxicity of intravenously injected bupivacaine in Sprague-Dawley rats. Our data show that both epinephrine and phenylephrine significantly increased cardiorespiratory toxicity of intravenously injected bupivacaine (P less than 0.007, X2 analyses with Yates' correction). Our data suggest that epinephrine or phenylephrine added to bupivacaine may be more toxic to cardiorespiratory systems than plain bupivacaine or epinephrine alone or phenylephrine alone when injected intravenously in rats.