Pharmacodynamic interactions of cypermethrin and centrally acting drugs in mice

Cypermethrin a widely used insecticide of Pyrethroids (type II) group, was administered in mice at two dose levels (1/10 of LD50 i.e. 2.5 mg/kg and 1/5 of LD50 i.e. 5.0 mg/kg) and pharmacodynamic interactions of insecticide were studied with centrally acting drugs viz. pentobarbital sodium, amphetamine, pentylenetetrazole, acepromazine and analgin. Cypermethrin pretreatment potentiated the actions of pentobarbital and pentylene-tetrazole as evidenced by an increase in pentobarbital induced hypnosis and duration of pentylene-tetrazole induced chemoshock seizures. Tranquilizing action of acepromazine was potentiated but there was decrease in amphetamine influenced locomotor activity at both the dose levels. Cypermethrin pretreatment, however, did not have any pharmacodynamic interaction with analgin.