What is ranitidine (Zantac) used for?

Ranitidine (Zantac): Uses and Clinical Applications

Ranitidine is a histamine H2-receptor antagonist primarily used to treat conditions related to excess gastric acid production including duodenal ulcers, gastric ulcers, GERD, erosive esophagitis, and pathological hypersecretory conditions such as Zollinger-Ellison syndrome.

Primary Indications

• Short-term treatment of active duodenal ulcer, with most patients healing within 4 weeks 1
• Maintenance therapy for duodenal ulcer patients at reduced dosage after healing of acute ulcers 1
• Treatment of pathological hypersecretory conditions (e.g., Zollinger-Ellison syndrome and systemic mastocytosis) 1, 2
• Short-term treatment of active, benign gastric ulcer, with most patients healing within 6 weeks 1
• Maintenance therapy for gastric ulcer patients at reduced dosage after healing of acute ulcers 1
• Treatment of gastroesophageal reflux disease (GERD), with symptomatic relief commonly occurring within 24 hours 1
• Treatment of endoscopically diagnosed erosive esophagitis 1, 3
• Maintenance of healing of erosive esophagitis 1

Mechanism of Action and Efficacy

• Ranitidine inhibits gastric acid secretion by blocking histamine H2-receptors, making it 4-10 times more potent than cimetidine in inhibiting stimulated gastric acid secretion 4, 2
• For duodenal ulcers, ranitidine 300mg daily (either as 150mg twice daily or 300mg at bedtime) is effective for healing, with rates of 73% at 4 weeks 1
• For gastric ulcers, ranitidine shows healing rates of 68% at 6 weeks compared to 51% with placebo 1
• In GERD, ranitidine 150mg twice daily significantly reduces heartburn frequency and severity within 1-2 weeks 1
• For erosive esophagitis, ranitidine 150mg four times daily achieves healing rates of 47%, 71%, and 84% at weeks 4,8, and 12 respectively 1
• Maintenance therapy with ranitidine 150mg at bedtime significantly reduces duodenal ulcer recurrence rates (35% vs 59% with placebo at 12 months) 1, 5

Preoperative Use

• Ranitidine may be used preoperatively in patients at increased risk of pulmonary aspiration 6
• Meta-analysis of randomized controlled trials shows that orally-administered ranitidine effectively reduces gastric volume and acidity, the frequency of gastric volume > 25 mL, the frequency of gastric pH levels < 2.5, and the risk of aspiration during the perioperative period 6
• Intravenous ranitidine shows similar results for gastric pH but equivocal findings for gastric volume 6

Other Clinical Applications

• Ranitidine has shown efficacy in reducing water-electrolyte losses in conditions like short bowel syndrome 7
• Ranitidine 300mg daily for 2 weeks has improved cough in 54% of patients with gastro-esophageal reflux related cough 7
• For reflux cough management, full acid suppression may require a combination of twice daily PPIs and nocturnal H2 antagonists 7
• In dermatology, ranitidine 300mg twice daily has been used in one open-label study for treating multiple common or plane warts, with 49% of patients showing complete response after 4 months 6

Dosing Considerations

• Standard adult dosing for most indications is 150mg twice daily or 300mg once daily at bedtime 1
• For erosive esophagitis, a higher dose of 150mg four times daily is more effective 1, 3
• For maintenance therapy, 150mg once daily at bedtime is typically sufficient 1, 5
• Pediatric dosing for GERD is 5-10 mg/kg/day divided in 2-3 doses 7
• Dosage adjustments may be needed in patients with renal impairment 8

Safety Profile and Side Effects

• Ranitidine is generally well-tolerated with infrequent adverse reactions 8
• Unlike cimetidine, ranitidine lacks antiandrogenic effects and does not significantly alter hepatic metabolism of drugs 4, 2
• CNS side effects (nervousness, anxiety, insomnia, difficulty concentrating) are less common with ranitidine than with cimetidine 6
• Gastrointestinal side effects (nausea, anorexia) occur in approximately 1-3% of persons taking ranitidine 6
• Side effects are usually mild and often cease soon after discontinuing the drug 6

Comparative Efficacy

• Ranitidine is less effective than proton pump inhibitors (PPIs) for symptom relief and healing of erosive esophagitis 7
• Tachyphylaxis (diminishing response) can develop within 6 weeks of treatment initiation, limiting ranitidine's potential for long-term use 7
• Ranitidine 150mg four times daily is more effective than cimetidine 800mg twice daily in healing erosive esophagitis 3
• For standard duodenal and gastric ulcer treatment, ranitidine 150mg twice daily is at least as effective as cimetidine 800-1000mg daily 8

Clinical Considerations and Precautions

• Concomitant antacids may be given as needed for pain relief to patients with active ulcers, hypersecretory states, GERD, or erosive esophagitis 1
• Ranitidine should not be routinely administered as a preoperative gastrointestinal stimulant for patients with no apparent increased risk for pulmonary aspiration 6
• When used with NSAIDs, H2-blockers like ranitidine may help reduce GI complications, though proton pump inhibitors are generally preferred for this purpose 6
• In patients with renal insufficiency, seizure disorders, or certain psychiatric disorders, dosage adjustments may be necessary to avoid more severe side effects 6