Aciloc (ranitidine)

# Aciloc (ranitidine) ## Overview Ranitidine is a histamine-2 (H2) receptor antagonist that inhibits gastric acid secretion by competitively blocking H2 receptors on gastric parietal cells. **Note:** Ranitidine has been withdrawn from many global markets (including the U.S. FDA market) due to contamination with N-nitrosodimethylamine (NDMA), a probable human carcinogen. Ensure local regulatory status before use. ## Primary Indications * Duodenal ulcer (active or maintenance) * Benign gastric ulcer * Gastroesophageal reflux disease (GERD) * Erosive esophagitis * Pathological hypersecretory conditions (e.g., Zollinger-Ellison syndrome) ## Adult Dosing * **Active Duodenal/Gastric Ulcer:** 150 mg twice daily or 300 mg at bedtime. * **Maintenance (Ulcer):** 150 mg once daily at bedtime. * **GERD:** 150 mg twice daily. * **Erosive Esophagitis:** 150 mg four times daily. * **Hypersecretory Conditions:** 150 mg twice daily (may increase up to 6 g/day based on patient need). ## Pediatric Dosing * **GERD/Peptic Ulcer (1 month to 16 years):** 2–4 mg/kg/day divided twice daily. * *Maximum Dose:* 300 mg/day. * *Note:* Dosing varies significantly by institutional protocol and age; consult local pediatric formulary guidelines. ## Dose Adjustments * **Renal Impairment:** Adjust dose if CrCl < 50 mL/min. Reduce dose to 150 mg every 24 hours or increase dosing interval. * **Hepatic Impairment:** Use with caution; monitor closely as ranitidine is metabolized by the liver. ## Contraindications * Hypersensitivity to ranitidine or other H2-receptor antagonists. * History of acute porphyria. ## Adverse Effects * **Common:** Headache, constipation, diarrhea, nausea. * **Serious:** Bradycardia or tachycardia (IV administration), confusion (especially in elderly/renal impairment), thrombocytopenia, elevated liver enzymes, hepatitis. ## Key Drug Interactions * **CYP450:** Ranitidine has a weak affinity for CYP450 enzymes but may inhibit the absorption of drugs requiring acidic environments (e.g., ketoconazole, atazanavir, iron salts). * **Procainamide:** May decrease renal clearance of procainamide, increasing toxicity risk. * **Warfarin:** Monitor INR, as minor changes in anticoagulation control have been reported. ## Monitoring * Monitor renal function (CrCl) to adjust dosage. * Monitor for mental status changes, particularly in patients >65 or those with renal/hepatic failure. * Assess for occult blood in stool if treating active ulcers. ## Clinical Pearls * **IV to PO Switch:** Oral bioavailability is ~50%. IV dosing is typically 50 mg every 6–8 hours. * **Tolerance:** Tachyphylaxis can occur with chronic H2RA use. * **NDMA Alert:** Due to NDMA impurities, alternative therapies (e.g., Famotidine or Proton Pump Inhibitors) are generally preferred unless ranitidine is explicitly required by local protocols and deemed safe. *** *Educational Disclaimer: This information is for educational purposes only. Always consult current institutional guidelines, local regulatory authorities, and the official package insert or drug monograph before prescribing or administering medication.*