What is/are Nitrofurantoin?
Nitrofurantoin is an antibiotic which is marketed under the following brand names; Niftran, Furadantin, Furabid, Macrobid, Macrodantin, Nitrofur Mac, Nitro Macro, Nifty-SR, Martifur-MR, Uro-Tablinen or Nifuretten (in Germany), Martifur-100 (in India), Urantoin, Nifuran (in Macedonia) and Uvamin (in Middle East). It is usually used in treating urinary tract infection. It is often used against E. coli.
Resistance to other antibiotics has led to increased interest in this agent. It is sometimes described as being appropriate to use in pregnant patients (along with other agents such as sulfisoxazole or cephalexin). This is in contrast to agents such as trimethoprim and ciprofloxacin which may not be appropriate for pregnant women.
Adult doses of nitrofurantoin for a urinary tract infections can be 100mg two times daily, or 50mg four times daily for seven days. For less severe cases of UTIs, the dosage may be prescribed as shortened to 3 days. The pediatric dose is 5–7 mg/kg/day in four divided doses. or when in 25 mg/5ml oral suspension then pediatric dose is 3 mg/kg/day in four divided doses. Nitrofurantoin should be taken with food, as this improves the absorption of the drug by 45%.
Nitrofurantoin is only clinically proven for use against E. coli or Staph. saprophyticus. It may also have in vitro activity against:
- Coagulase negative staphylococci
- Enterococcus faecalis,
- Staphylococcus aureus,
- Streptococcus agalactiae,
- Citrobacter species, and
- Klebsiella species,
and is used in the treatment of infections caused by these organisms. Many or all strains of the following are resistant to nitrofurantoin:
- Enterobacter species
- Klebsiella species
- Acinetobacter species,
- Morganella species,
- Proteus species,
- Providentia species,
- Serratia species,
- Pseudomonas species.
Nitrofurantoin must never be used to treat pyelonephritis, prostatitis, renal abscess, and pyeloempyema because of extremely poor tissue penetration and low blood levels, although the patient information leaflet states it is used to prevent and treat infections of the bladder, kidney and other parts of the urinary tract. Urinary catheter infections may be treated with nitrofurantoin if there are no systemic features; the catheter must be changed after 48 hours of antibiotics and treatment is ineffective if the catheter is not replaced or removed.
The most common side effects with nitrofurantoin are nausea, vomiting, and diarrhea; less common reactions include fever, chills, and various other hypersensitivity reactions. It can also cause pulmonary fibrosis and Drug-induced autoimmune hepatitis. All these side effects are much more common in the elderly hence this antibiotic is strongly not recommended for older adults according to 2012 AGS Beers Criteria.
Patients should be informed that nitrofurantoin colours urine brown; this is completely harmless. Neonates (babies up to the age of one month) have immature enzyme systems in their red blood cells (glutathione instability) and nitrofurantoin must therefore not be used because it can cause haemolytic anaemia. For the same reason, nitrofurantoin should not be given to pregnant women after 38 weeks of pregnancy, or who are about to give birth.
Nitrofurantoin is contraindicated in patients with decreased renal function (CrCl < 60mL/min) due to systemic accumulation and subtherapeutic levels reached in the urinary tract. However, a retrospective chart review may suggest that nitrofurantoin is not contraindicated in this population.
Mechanism of action
The mechanism of action of nitrofurantoin is unique and complex. The drug works by damaging bacterial DNA, since its reduced form is highly reactive. This is made possible by the rapid reduction of nitrofurantoin inside the bacterial cell by flavoproteins (nitrofuran reductase) to multiple reactive intermediates that attack ribosomal proteins, DNA, respiration, pyruvate metabolism and other macromolecules within the cell. Nitrofurantoin exerts greater effects on bacterial cells than mammalian cells because bacterial cells activate the drug more rapidly. It is not known which of the actions of nitrofurantoin is primarily responsible for its bactericidal activity.
This article uses material from the Wikipedia article Nitrofurantoin, which is released under the Creative Commons Attribution-Share-Alike License 3.0.