Spectrum of the antimalarial activity of a new macrolide antibiotic midecamycin in mice and monkeys.

Abstract

The antimalarial activity of a new macrolide antibiotic, midecamycin, has been evaluated against a sensitive strain of Plasmodium berghei, a chloroquine-resistant strain of P. yoelii nigeriensis and a simian parasite, P. cynomolgi B. The ED50 and ED90 values of this antibiotic administered in two divided daily doses were found to be 37.15 +/- 3.51 and 100.84 +/- 7.54 mg/kg, respectively, against P. berghei and 362.34 +/- 85.33 and 878.04 +/- 10.02 mg/kg, respectively, against P. yoelii nigeriensis. Doses above 45 mg/kg for 4 days significantly extended the mean survival time of treated mice infected with either of the two parasites. However, no appreciable blood schizontocidal (at 100 mg/kg X 7 days), anti-relapse (at 100 mg/kg X 7 days) or causal prophylactic activities (at 200 mg/kg X 3 days) were observed against P. cynomolgi infection in rhesus monkeys.