Nitrofurantoin Manx Healthcare (Nitrofurantoin, Macrocrystalline)

• Nitrofurantoin is a nitrofuran antibiotic used to manage infections of the urinary tract.
• Uncomplicated urinary tract infection (cystitis): eliminates causative bacteria and alleviates urinary symptoms.
• Prophylaxis of recurrent urinary tract infection: reduces the frequency of future infection episodes when taken long‑term.
• Acute uncomplicated cystitis in women: provides rapid bacterial clearance and symptom improvement.

• Nitrofurantoin exerts its antibacterial effect by entering bacterial cells and inhibiting enzymes involved in carbohydrate metabolism, particularly the bacterial electron transport chain. This disruption impairs synthesis of nucleic acids and proteins, leading to bacterial cell death, especially in Gram‑negative uropathogens such as Escherichia coli. The drug is rapidly excreted unchanged in the urine, achieving high concentrations that exceed the minimum inhibitory concentrations for common uropathogens, thereby enhancing its therapeutic efficacy in the urinary tract.

Nitrofurantoin may cause a range of adverse reactions, varying from mild to serious.

Common Side Effects

• Nausea: mild stomach upset that may occur after dosing.
• Diarrhea: loose stools, often transient.
• Headache: mild to moderate head pain.
• Loss of appetite: reduced desire to eat.

Serious or Rare Side Effects

• Pulmonary toxicity: interstitial lung disease or fibrosis requiring medical attention.
• Hepatic injury: elevated liver enzymes or hepatitis.
• Peripheral neuropathy: tingling or numbness in extremities, especially with prolonged use.

• When prescribing Nitrofurantoin, consider the following precautions to ensure safe use.
• Renal function assessment: evaluate creatinine clearance before initiating therapy.
• G6PD deficiency: avoid use in patients with known glucose‑6‑phosphate dehydrogenase deficiency.
• Pregnancy safety: category B; use only if clearly needed during pregnancy.
• Duration of therapy: limit to the shortest effective course to reduce risk of toxicity.
• Monitoring for pulmonary symptoms: discontinue if signs of lung irritation develop.
• Store at ambient temperature: keep below 25 °C in the original packaging, protected from moisture.

Nitrofurantoin can interact with several medicines; some require avoidance while others need careful monitoring.

Major Interactions (Avoid)

• Antacids containing aluminum or magnesium: reduce nitrofurantoin absorption.
• Probenecid: decreases renal excretion, increasing plasma levels.
• Methenamine: concurrent use may diminish antibacterial efficacy.
• Warfarin: nitrofurantoin can potentiate anticoagulant effect, increasing INR.

Moderate Interactions (Monitor Closely)

• Oral contraceptives: may reduce effectiveness, consider alternative contraception.
• Vitamin C supplements: increased urinary acidity can affect drug stability.
• Diuretics: may increase risk of crystalluria, monitor renal function.