Influence of pH on the amoebicidal activity of systemically active amoebicides against axenic Entamoeba histolytica
Dutta, G.P.; Narain, L.
Indian Journal of Experimental Biology 16(7): 838-840
1978
ISSN/ISBN: 0019-5189 PMID: 29834 Document Number: 128109
Metronidazole was equally active at pH levels 5.8 and 7.2 and showed ameobicidal action at 4-8 .mu.g/ml. Other drugs, however, showed high amoebicidal activity only at alkaline pH, i.e., chloroquine at 500 .mu.g, emetine and dehydroemetine at 7.8 .mu.g, mepacrine and camoquine at 15.6 .mu.g/ml. At acid pH chloroquine showed amoebicidal activity at > 4000 .mu.g, emetine and dehydroemetine at 125 .mu.g, mepacrine at 125 .mu.g and camoquine at 62.5 .mu.g/ml. Since the pus in amoebic liver abscess cases is acidic (pH 5.5-5.8), it is quite likely that the occasional failure of emetine, dehydroemetine and chloroquine therapy in unaspirated abscess cases might be possibly due to very low activity of these drugs at acid pH due to the presence of pus.