METHITURAL, A NEW INTRAVENOUS ANESTHETIC: COMPARISON WITH THIOPENTAL IN THE CAT, DOG AND MONKEY

¹ Department of Pharmacology, Schering Corporation, Bloomfield, New Jersey

Investigations in the cat, dog and monkey showed methitural to possess twothirds the anesthetic potency of thiopental.

Following equivalent anesthetic doses, recovery from anesthesia was significantly more rapid with methitural than with thiopental, and cumulative action with methitural considerably less than that observed with either thiopental or thiamylal.

There was less respiratory depression and less cardiac acceleration with methitural than with thiopental anesthesia, but a greater incidence of reversible cardiac arrhythmias (ectopic beats and bigeminy) and abnormal vagal reflexes which were reduced or abolished by atropine premedication.

Atropine, morphine, succinylcholine, d-tubocuranine and combinations thereof were found to be compatible with methitural in the dog. Atropine, as well as morphine, significantly increased the depth and duration of anesthesia and extended recovery of the righting reflex.

No tolerance or cumulative action was noted in the dog following the daily intravenous administration of methitural (45 mgm./kgm.) or thiopental (25 mgm./kgm.) for thirty days. Microscopic examination of the tissues following chronic administration showed thiopental to be considerably more toxic to the liver than methitural.