T IS ACCEPTED that the most frequent cause I of adverse reactions following administraton of local anesthetic agents is toxicity from accumulation of high blood/drug levels, produced by excessive dosage, rapid absorption of the agent into the circulation, or inadvertent intravascular injection.In 1925, Tatum and associates1 first proposed the use of barbiturates for prophylaxis to prevent convulsions following administration of local anesthetic agents. This concept is still favored by some2 but is opposed by others.3~4 Moore5 believes that barbiturates, although providing adequate sedation in certain cases, may make some patients restless and difficult to control. As antidote against systemic toxic reactions, oxygen inhalation has been recommended by Moore and Bridenbaughe and by Daos and coworkers.'Two frequently-used barbiturates, and four other drugs recently introduced into anesthesiology, were studied for their effectiveness in preventing convulsions in rats following intraperitoneal injection of local anesthetic agents.
METHODThe intraperitoneal LD,, doses of the hydrochloride salts of prxaine, tetracaine, and lidocaine were determined, as reported in a previous communication.8 At the dosages given, 80 percent of the rats convulsed, while 50 percent died. The amount of the pretreatment agents required to produce anesthesia was calculated as the minimum dose necessary to produce loss of the righting reflex in the animals, followed by complete recovery after a variable period of sleep.9For the present study, 126 male SpragueDawley albino rats, between 4 and 6 weeks old and weighing 70 to 90 gm. each, were divided into seven groups of 18 rats each,