Nitrofurantoin Generics [uk] Limited (Nitrofurantoin)

Nitrofurantoin is a nitrofuran antibiotic used to treat infections of the urinary tract.

• Uncomplicated urinary tract infection (cystitis): eliminates susceptible bacteria, relieving dysuria, frequency and urgency.
• Prophylaxis of recurrent urinary tract infection: reduces recurrence rates in patients with a history of repeated infections.
• Acute lower urinary tract infection: provides rapid bactericidal activity to resolve symptoms.

• Nitrofurantoin is reduced by bacterial nitroreductases to reactive nitro‑furanyl intermediates that bind to bacterial DNA and other macromolecules. This damage interferes with nucleic acid synthesis and essential enzymatic processes, leading to bacterial cell death. Its selective accumulation in the renal tubules ensures effective antimicrobial activity at the site of infection.

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

Common Side Effects

• Nausea: mild stomach upset often occurring early in therapy.
• Diarrhea: loose stools that may be self‑limiting.
• Rash: skin redness or itching.

Serious or Rare Side Effects

• Pulmonary toxicity: interstitial pneumonitis or fibrosis requiring discontinuation.
• Hepatic injury: elevated liver enzymes or hepatitis.
• Peripheral neuropathy: tingling or numbness, especially with prolonged use.

When prescribing nitrofurantoin, several safety considerations should be reviewed to minimize risk.

• Renal function assessment: evaluate creatinine clearance before initiating therapy.
• Pregnancy: avoid use in the first trimester and near term unless benefits outweigh risks.
• G6PD deficiency: contraindicated due to risk of hemolysis.
• Elderly patients: monitor for signs of pulmonary toxicity and adjust dose if needed.
• Drug interactions: review concomitant medications for potential absorption or metabolic effects.
• Store at ambient temperature: keep below 25 °C in the original packaging, protected from moisture.

Nitrofurantoin can interact with other medicines, affecting its absorption or increasing toxicity.

Major Interactions (Avoid)

• Antacids containing magnesium or aluminum: markedly reduce nitrofurantoin absorption.
• Probenecid: increases nitrofurantoin serum concentrations, raising toxicity risk.
• Cimetidine: may elevate nitrofurantoin levels, leading to adverse effects.

Moderate Interactions (Monitor Closely)

• Warfarin: nitrofurantoin may potentiate anticoagulant effect; monitor INR.
• Phenytoin: may decrease nitrofurantoin efficacy; assess clinical response.
• Fluoroquinolones: combined use may increase risk of tendonitis; observe for musculoskeletal symptoms.