About ornidazolea nitro imidazole derivative, antiprotozoal antibiotic,antimicrobial.mechanism of action of ornidazoleornidazole is a nitro imidazole which has broad spectrum cidal activity against protozoa and some anaerobic bacteria. its selective toxicity to anaerobic microbes involves 1. drug enters the cell by diffusion, 2. nitro group of drug is reduced by redox proteins present only in anaerobic organisms to reactive nitro radical which excerts cytotoxic action by damaging dna and other critical biomolecules. 3. dna helix destabilization &strand breakage has been observed. indications for ornidazole1.amoebiasis 2.giardiasis 3.trichomonas vaginitis 4.anaerobic bacterial infections 5.bacterial vaginosis