Metronidazole
FlagylPubChem CID 4173 · 3D model
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Gets switched on inside oxygen-free bacteria and parasites, where it damages their DNA and kills them.
How it works
Metronidazole is essentially inactive until it gets inside bacteria or parasites that live without oxygen. Once inside, the organism's own chemistry switches the drug on, turning it into a reactive form that attacks and damages the invader's DNA, which kills it. Because this activation step only happens in oxygen-free (anaerobic) organisms, metronidazole only works against those bugs and certain parasites, not against ordinary oxygen-using bacteria. The drugmaker's label is upfront that scientists don't know exactly how metronidazole works in full molecular detail, even though its DNA-damaging effect is well documented.
What it’s used for
Used to treat trichomoniasis, a sexually transmitted parasite infection, in both the infected person and their sexual partner (even if the partner has no symptoms), to keep them from reinfecting each other. Also treats amebic dysentery and liver abscesses caused by a different parasite, though a liver abscess may still need to be drained. It's widely used for serious infections caused by bacteria that thrive without oxygen — including infections deep in the abdomen, skin infections, female reproductive-organ infections, bloodstream infections, and some bone, brain, and lung infections. When an infection involves both oxygen-loving and oxygen-avoiding bacteria together, metronidazole is paired with a second antibiotic that covers the oxygen-loving ones.
- Mechanism
- Nitroimidazole, forms DNA-damaging free radicals inside anaerobic bacteria/protozoa
- Drug class
- Small molecule
- Therapeutic area
- Antibiotic / Antiprotozoal