Flagyl 400 mg - 400 mg metronidazole/tablet. Flagyl S - 200 mg - metronidazole benzoate/5 mL of liquid. Flagyl suppositories - 500 mg metronidazole/suppository. Inactive ingredients: Flagyl 200 mg 400 mg tablets also contain calcium hydrogen phosphate, maize starch, povidone, macrogol 400...