Toxicities and the rates of penetration of O-ethyl-S-(2-dimethylaminoethyl)-methylphosphonothioate into the blood following different routes of intoxication.

Toxicities of O-ethyl-S-(2-dimethylaminoethyl)-methylphosphonothioate were determined by i. v. (17.0 microgram/kg), i.m. (23.6 microgram/kg), i. p. (54.5 microgram/kg) and p. o. (121.9 microgram/kg) administration to female rats. Following intoxication with this compound (42 microgram/kg) at these routes of administration, acetylcholinesterase activity in the blood was continuously monitored and half-times of inhibition in vivo were determined. It appears from a comparison of inhibitions in vivo and in vitro that only a part of the dose administered is effective to inhibit acetylcholinesterase in the blood vessel.