Animal studies on the treatment of poisoning by amitraz (a formamidine pesticide) and xylene.

In Charles River CD rats the pesticide MITAC 20 EC (containing amitraz and 75% xylene) given orally at an LD80 dose caused toxicity featuring hypothermia, reduced spontaneous activity, episodes of increased activity and minor signs of general debilitation. Recovery in survivors was complete within about 8 days. Therapies including absorption retardants, diuretics, reduction of urine pH, thermal support and treatment with phentolamine or nikethamide were given to groups showing these signs of poisoning. None of the therapies gave consistent evidence of benefit during acute poisoning in terms of reduced intensity or duration of symptoms or reduced mortality. Comparison with animals given amitraz alone suggested that the hypothermia and the later phase of reduced spontaneous activity were attributable to the pharmacological effects of amitraz. While the product was apparently more acutely toxic by the oral route than xylene alone, the evidence was that xylene caused the early signs of poisoning. This work indicates that any case of poisoning by ingestion of MITAC 20 EC should initially be treated for the xylene exposure. There is no specific therapy or antidote for the subsequent possible pharmacological effects of amitraz. Many other pesticides also contain high proportions of aromatic solvents and the importance of the solvent in cases of ingestion is seen to be applicable to a variety of pesticides as well as MITAC 20 EC.