Toxicity of pyrethrum

Table II. Relative Toxicity of Pyrethrum LD50, and LD75 Levels Experiment A Constituents at LD25, Experiment B ...

Piperonyl butoxide, isoniazid, and SKF 525A and related chemicals are inhibitors of various xenobiot-ic-metabolizing enzymes. For instance, piperonyl butoxide increases the toxicity of pyrethrum (an insecticide) by inhibiting MFO activity in insects that detoxifies this agent. Isoniazid, when taken along with phenytoin, lengthens the plasma half-life of the antiepileptic drug and increases its toxicity. Iproniazid inhibits monoamine oxidase and increases the cardiovascular effects of tyramine, which is found in cheese and which is normally readily metabolized by the oxidase. 

Bund. H., MLinger. K. and DeFeo. J.J. (1977). The oral toxicity of pyrethrum. alone and combined with synergists. Fyn-ih. Fost 12. 59. 

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