Nitroimidazoles are probably converted in an anaerobic environment into metabolites without a nitro group, which is toxic for protozoa (a prodrug). The mechanism of action of nitroimidazoles is inhibition of DNA synthesis and degradation of existing DNA.
Metronidazole and tinidazole are effective in treatment of amebiasis, giardiasis and trichomoniasis. Metronidazole is also a major anaerobe antibacterial drug. Side effects of metronidazole include headache, nausea, dry mouth and metallic taste.
Pregnant and lactating women should NOT use nitroimidazoles.
Extra info: The effects of nitroimidazoles on pregnancy and lactation are unknown, but embryotoxicity has been shown in animal trials