Clinical Overview
Nitrofurantoin Tablets / Sustained Release (50mg, 100mg) is a synthetic nitrofuran bactericidal antibiotic on the WHO Model List of Essential Medicines. Bacterial nitroreductases intracellularly reduce nitrofurantoin into highly reactive, short-lived electrophilic intermediates that indiscriminately attack bacterial ribosomal proteins, DNA, RNA, and metabolic enzymes. It concentrates specifically in renal tubular fluid and bladder urine (therapeutic urine concentrations >100 mcg/mL) with negligible systemic tissue levels, minimizing disruption to normal vaginal and bowel microflora and exhibiting minimal bacterial resistance after decades of use. Indicated for treatment and long-term prophylaxis of acute uncomplicated lower urinary tract infections (cystitis) caused by susceptible E. coli, Enterococcus faecalis, and Klebsiella species.
Active Pharmaceutical Ingredients
Verified Clinical References
Usage Guidelines
Acute cystitis: Take 100 mg orally twice daily (sustained-release) or 50-100 mg four times daily with food or milk for 5 to 7 days. Swallow whole; do NOT crush. Taking with food enhances bioavailability by over 40% and reduces nausea. Long-term prophylaxis: 50 mg to 100 mg once daily at bedtime.
General Administration Advice: Adhere strictly to the prescribed dosage, frequency, and treatment course. For oral medications, swallow with sufficient water. Never stop antibiotics, psychiatric medications, or antihypertensives abruptly without clinical direction.
Possible Side Effects
Common: Nausea, anorexia, headache, flatulence, harmless dark yellow or brown discoloration of urine. Rare/Severe: Acute/chronic pulmonary toxicity (interstitial pneumonitis, pulmonary fibrosis), peripheral neuropathy, drug-induced hepatotoxicity, and hemolytic anemia in G6PD deficiency.
*Note: Individual physiological responses vary. While many patients experience few or no side effects, notify your treating physician if adverse reactions persist or if hypersensitivity (angioedema, skin rash, dyspnea) occurs.
Precautions & Warnings
Black Box Warning: Pulmonary toxicity with chronic use; monitor for cough, dyspnea, and chest pain. Strictly contraindicated in patients with significant renal impairment (eGFR < 30-45 mL/min) as inadequate urinary drug concentrations occur with increased systemic toxicities. Contraindicated in late pregnancy (38-42 weeks) due to neonatal hemolytic anemia risk. Ineffective for pyelonephritis or perinephric abscess.
Schedule H (Prescription Required)
This medication is scheduled under statutory drug regulatory frameworks (CDSCO / Drugs & Cosmetics Rules). Dispensing requires a valid medical prescription from a registered medical practitioner. Self-medication or unsupervised dosage adjustment carries significant clinical risks.
Medical Disclaimer: Statutory Clinical Disclaimer: The information provided is for educational and price-transparency purposes only and does not constitute medical advice, nephrological diagnosis, or urological treatment recommendations. Always consult a registered nephrologist, urologist, or qualified medical practitioner before initiating, modifying, or discontinuing any kidney or urinary tract medication.