Correction of organophosphate-induced neuromuscular blockade by diphenhydramine
Clemmons, R.M.; Meyer, D.J.; Sundlof, S.F.; Rappaport, J.J.; Fossler, M.E.; Hubbell, J.; Dorsey-Lee, M.R.
American Journal of Veterinary Research 45(10): 2167-2169
1984
ISSN/ISBN: 0002-9645 PMID: 6497117 Document Number: 236086
Dogs exposed to topical organophosphate (fenthion) developed decreased plasma and muscle cholinesterase activities. After 2 doses were applied (one week between doses), plasma concentrations declined 80% and muscle cholinesterase activity was reduced by 56%. Decreasing responses to repetitive nerve stimulation developed after fenthion administration. Diphenhydramine, but not placebo, corrected the electrical abnormalities caused by organophosphate application, but without altering plasma or muscle cholinesterase activity. Control dogs housed in the same kennel had a slight decrease (18%) of plasma cholinesterase, indicating cross contamination. Diphenydramine may be effective in treating organophosphate-induced neuromuscular weakness which is refractory to other forms of therapy.