Circulatory Failure Caused by a Fungicide Containing Iminoctadine and a Surfactant: A Pharmacological Analysis in Rats

Abstract

The fungicide Befran (BFR), containing iminoctadine as an active ingredient and polyoxyethylene alkylether (POEAE) as a surfactant, has been known to cause circulatory failure in human acute oral poisoning. We investigated separately the effects of iminoctadine, POEAE, and BFR on heart rate and blood pressure of rats and also on isolated atria and aortas. In isolated rat atria, iminoctadine produced positive chronotropic and inotropic responses. In contrast, POEAE produced negative chronotropic and inotropic responses. BFR produced no effects at low concentrations, but significant negative chronotropic and inotropic responses at high concentrations. In isolated rat aortas, iminoctadine produced remarkable vasodilative responses, but POEAE produced vasoconstrictive responses. BFR produced both vasodilative and vasoconstrictive responses. When intravenously administered to anesthetized rats, iminoctadine produced hypotension and tachycardia in a dose-dependent manner. POEAE produced significant hypotension and slight bradycardia. BFR, at low doses, produced hypotension without elevation of heart rate. At high doses, it produced significant hypotension and tachycardia. From these results, it can be concluded that severe hypotension induced by BFR is due mainly to the vasodilative effect of iminoctadine and partly to the cardio-suppressive effect of POEAE.