Most commonly used antiamoebic drugs are effective in invasive
amebiasis, but their response against trophozoites of Entamoeba histolytica, present in the lumen of the human colon, is inadequate. We report the development of an antiamoebic
drug carrier that may be effective against
luminal infections. Our preparation consists of small
silica particles (5-10 microns in diameter) covalently linked to a potent antiamoebic
drug, 2-(4-aminophenoxymethyl)-5-nitro-1-methyl
imidazole.
Silica-
drug particles were injected into mice, hamsters, and guinea pigs. We found that trophozoites phagocytosed the particles in vivo and in vitro, followed by rapid cell death due to the released
drug. Analysis of mouse serum revealed that no
drug was absorbed from the intestine after placement of the
drug-containing particles in the intestine. The antiamoebic activity of particles recovered from the intestine was almost fully retained. This novel antiamoebic concept may be useful for
luminal therapy for asymptomatic
amebiasis and may minimize side effects and frequency of administration.