Suppression of Strychnine Convulsions by Barbiturates.

Abstract

Zerfas and McCallum 1 have found amytal (ethylisomyl barbituric acid) an extremely effective and life-saving antagonist to strychnine in man and the rabbit. Our observations on unanesthetized rabbits show that this property is also possessed by barbital (diethyl barbituric acid), phenobarbital (ethyl-phenyl), nembutal (ethyl-secondary amyl) and pernocton (B-bromallyl secondary butyl).

In a first series of redbrown rabbits, of 1.05 to 1.87 kg., we induced tetanic convulsions by injecting subcutaneously 0.6 nig. of Merck's neutral strychnine sulphate per kg., using 1:1000 solution. Two controls died in 18 and 13 minutes respectively. All the others, 11 in number, returned to a normal reflex state following treatment with Na phenobarbital or Na barbital, given by ear vein immediately on onset of convulsions and repeated as judged necessary to control their recurrence. The minimal total amounts per kg. necessary to secure this result were found to be, Na barbital 40 mg., and Na phenobarbital 1 to 5 mg., indicating a much greater activity of phenobarbital. All of the “treated” rabbits were apparently normal next day, and were later used for other purposes.

In a second series of short haired albino rabbits of 1.24 to 2.03 kg., 0.6 mg. strychnine sulphate per kg., similarly given, was followed by spontaneous recovery in 3 animals, but 0.9 mg. per kg. killed 3 other animals in 27, 30 and 55 minutes respectively. In the antagonism experiments 1.2 mg. per kg. was used. The results were similar to those in the first series except that doses of the hypnotic barbiturates closer to the “general anesthetic” level were necessary. The suppression of convulsions required in individual animals total doses in mg. per kg. as follows: Na nembutal 4, 14, Na amytal 15, Na phenobarbital, 30, (32 days), 60, pernocton 40 (25 days), 40 (16 days), Na barbital, 150; for comparison, chloral hydrate, 220, of which 30 subcutaneously (31 days).