Systemic effect of ipecac on acute toxicity of phenobarbital and theophylline in rats.

The emetic agent ipecac is widely used for the initial treatment of acute oral drug overdose. Its emetic and gastric evacuative efficacies have been studied extensively but its potential for pharmacologic interactions with various drugs and other possible poisons has not been explored. The purpose of this investigation was to determine if ipecac can alter the acute toxicity of two widely used drugs that act on the central nervous system, phenobarbital and theophylline. Ipecac syrup, 5 ml/kg, was administered by gavage to male Lewis rats either 1 hr before or 15 or 30 min after the start of an iv infusion of phenobarbital or theophylline. Control animals received the syrup vehicle only. Ipecac elicited vomiting-like behavior (frequent, wide opening of the mouth) for more than 1 hr. The drug infusion was stopped immediately after onset of the loss of righting reflex (phenobarbital) or maximal seizures (theophylline). Samples of cerebrospinal fluid, blood (for serum), and the brain were obtained at that time for analysis of drug concentrations. There were no significant differences between control and ipecac-treated animals with respect to the dose requirements and drug concentrations in cerebrospinal fluid, serum, and brain at the respective pharmacologic endpoint. It is concluded that ipecac has no apparent effect on the acute toxicity of phenobarbital and theophylline in rats.