The activity of methyl benzoquate and clopidol against Eimeria maxima: synergy and drug resistance.

Synergy between clopidol and methyl benzoquate against Eimeria maxima was shown to be supra-additive. Collateral sensitivity to these drugs could not be demonstrated in resistant lines of this parasite. Resistance to methyl benzoquate and clopidol was not transferred when lines of E. maxima, resistant to the respective drugs, were propagated together. The failure to demonstrate this phenomenon was judged not to be due to synergy between the drugs. Attempts to induce simultaneous was readily acquired by a line of E. maxima resistant to clopidol. Induced resistance to clopidol in a methyl benzoquate-resistant line required numerous passages.