Nippostrongylus brasiliensis: effect of dexamethasone upon anthelmintic efficacy

A study has been made to determine the chemotherapeutic susceptibility of natural and “steroid sustained” Nippostrongylus brasiliensis infections in rats. Dexamethasone in the drinking water (2.5 × 10^?4 mg/ml) aided establishment of greater parasite populations but restricted growth of young rats. Comparison trials with thiabendazole, cambendazole, and parbendazole, as well as 10 candidate drugs, showed that the parasiticidal activity of these materials was not significantly altered between the 10-day-old naturally maintained and the 17-day-old steroid-treated parasitic infections. As expected, 17-day-old naturally maintained parasite populations were highly susceptible to the anthelmintic action of these materials. In one instance, the toxic response elicited by a candidate drug was apparently potentiated by dexamethasone.