Nitrofurantoin
A nitrofuran antibiotic that concentrates in urine, used to treat and prevent bladder infections but not kidney infections.
Drug card
- Class
- Nitrofuran
- How it works
- Forming reactive products inside bacteria that damage their DNA and proteins
- Used for
- Uncomplicated bladder infections (cystitis)
- Preventing repeat urinary tract infections
- Known for
- Lung fibrosis with long-term use
- Peripheral neuropathy, sometimes irreversible
Study it as a flashcard, and it comes back before you forget it.
Mechanism of action
How does nitrofurantoin work?
Bacterial flavoproteins reduce it to reactive intermediates that damage DNA, ribosomal proteins and other macromolecules. It reaches useful levels only in urine, so it treats cystitis, not pyelonephritis. It has no activity against Pseudomonas and little against most Proteus strains.
Uses
What is nitrofurantoin used for?
- Uncomplicated bladder infections (cystitis)
- Preventing repeat urinary tract infections
Side effects
Side effects of nitrofurantoin
- Lung fibrosis with long-term useKnown forSerious
- Peripheral neuropathy, sometimes irreversibleKnown forSerious
- Nausea
- Loss of appetite
- Headache
- Diarrhea
- Dark yellow or brown urine
- Acute lung reaction: fever, cough, breathlessnessSerious
- Hepatitis and cholestatic jaundiceSerious
- Hemolytic anemia in G6PD deficiencySerious
- AnaphylaxisSerious
- C. difficile diarrheaSerious
Known for marks what an exam expects you to know it for.
Watch for
Cautions and what sets it apart
- Contraindicated in significant kidney impairment (creatinine clearance under 60 mL/min in the US label), as the drug builds up.
- Contraindicated at term, in labor and in babies under 1 month, because it can cause hemolytic anemia.
- Magnesium trisilicate antacids cut absorption; probenecid raises blood levels and lowers urine levels.
- Long-term use: check lungs, liver and kidney function regularly.
Good to know: Usable in early and mid pregnancy, but avoided near term because it can make the baby's red cells break down.
Remember it
A way to remember it
Nitrofurantoin never leaves the bladder.
It reaches useful levels only in urine, so it treats and prevents bladder infections but not pyelonephritis or infections elsewhere in the body.
Written for biofideX
Its class
Nitrofurans
Nitrofurans are taken up by bacteria, where flavoproteins and other reducing enzymes turn them into reactive intermediates. These damage DNA, ribosomal proteins and other large molecules, so the bacteria stop making DNA, RNA, protein and cell wall. Nitrofurantoin reaches useful levels only in urine, not in body tissues, so it treats bladder infections alone.
Easily mixed up with nitroimidazoles and antibacterial folate antagonists.
Sources
Checked against
Written for biofideX in plain words, after checking these references:
For learning pharmacology, not for treatment decisions: no doses are given, and a prescriber, pharmacist or the product's own label is the word on any one patient. Spotted a mistake? Tell us and we'll correct it.
Antibiotics: DNA, folate and tuberculosis
Nitrofurantoin is one of 11 drugs practiced together here: their classes, how they work, what they treat and what they're known for.
Start Practicing