Ranitidine is a histamine H2-receptor antagonist that effectively reduces stomach acid production. It is widely prescribed for the management and treatment of various acid-related gastrointestinal disorders. By competitively inhibiting histamine at H2 receptors of gastric parietal cells, ranitidine decreases both the volume and concentration of gastric acid, providing symptomatic relief and promoting healing of affected tissues. Its well-established efficacy and favorable safety profile have made it a trusted option in clinical practice for decades.

Features

• Belongs to the histamine H2-receptor antagonist class
• Available in oral tablet, effervescent tablet, syrup, and injectable formulations
• Typical strengths include 75 mg, 150 mg, and 300 mg
• Rapid onset of action, with effects noticeable within 1–2 hours after administration
• Duration of acid suppression lasts up to 12 hours per dose
• Demonstrated bioavailability of approximately 50%
• Metabolism primarily hepatic, with renal excretion of unchanged drug and metabolites

Benefits

• Provides rapid and sustained relief from heartburn, acid indigestion, and sour stomach
• Effectively promotes healing of gastric and duodenal ulcers
• Reduces the frequency and severity of gastroesophageal reflux disease (GERD) symptoms
• Helps manage pathological hypersecretory conditions such as Zollinger-Ellison syndrome
• Prevents stress ulcers and acid aspiration syndrome in hospitalized patients
• Offers convenient dosing options suitable for both acute and maintenance therapy

Common use

Ranitidine is commonly prescribed for the short-term treatment of active duodenal ulcers and benign gastric ulcers. It is also indicated for maintenance therapy after healing of acute ulcers to prevent recurrence. In gastroesophageal reflux disease (GERD), ranitidine provides effective symptomatic relief by reducing esophageal acid exposure. Additionally, it is used for the management of pathological hypersecretory conditions, including Zollinger-Ellison syndrome and systemic mastocytosis. Ranitidine may be administered prophylactically to prevent stress ulcers in critically ill patients and to reduce the risk of acid aspiration syndrome during anesthesia.

Dosage and direction

For active duodenal ulcer: 150 mg twice daily or 300 mg once daily for 4–8 weeks. For maintenance therapy: 150 mg at bedtime. For gastric ulcer: 150 mg twice daily for up to 8 weeks. For GERD: 150 mg twice daily for up to 12 weeks. For pathological hypersecretory conditions: 150 mg twice daily, adjusted based on patient response (maximum 6 g daily). For heartburn and acid indigestion: 75 mg as needed, not to exceed 150 mg in 24 hours. Tablets should be swallowed whole with water, with or without food. The injection form is administered intravenously under medical supervision. Dosage adjustments are necessary in patients with renal impairment.

Precautions

Patients with phenylketonuria should avoid effervescent formulations containing phenylalanine. Use with caution in patients with hepatic impairment, as ranitidine is metabolized in the liver. Renal function should be monitored in patients with pre-existing kidney disease, and dosage adjustments may be necessary. Long-term therapy may lead to vitamin B12 deficiency due to reduced acid secretion affecting absorption. Ranitidine may mask symptoms of gastric malignancy; proper diagnosis should be established before initiation of therapy. Elderly patients may be more susceptible to adverse effects and require careful monitoring.

Contraindications

Ranitidine is contraindicated in patients with known hypersensitivity to ranitidine or any component of the formulation. It should not be used in patients with acute porphyria, as it may precipitate attacks. The injection form is contraindicated in patients with a history of acute intermittent porphyria. Concomitant use with certain HIV protease inhibitors (particularly atazanavir) is contraindicated due to significant reduction in antiviral efficacy. Ranitidine is not recommended for patients with severe renal impairment (CrCl <30 mL/min) without appropriate dosage adjustment.

Possible side effect

Common side effects include headache, dizziness, constipation, and diarrhea. Less frequently, patients may experience nausea, vomiting, abdominal discomfort, or rash. Rare but serious adverse effects include hepatotoxicity (elevated liver enzymes, hepatitis), blood dyscrasias (thrombocytopenia, leukopenia, agranulocytosis), and cardiovascular effects (bradycardia, AV block). Psychiatric effects such as confusion, depression, and hallucinations have been reported, particularly in elderly or severely ill patients. Prolonged use may be associated with increased risk of pneumonia and enteric infections due to reduced gastric acidity.

Drug interaction

Ranitidine may decrease the absorption of drugs requiring acidic gastric environment for optimal bioavailability, including ketoconazole, itraconazole, and atazanavir. It may potentiate the effects of warfarin and other oral anticoagulants by competing for hepatic metabolism. Concurrent use with procainamide may increase procainamide levels due to reduced renal clearance. Ranitidine may alter the bioavailability of certain pH-dependent formulations. Concomitant administration with high-dose antacids may slightly reduce ranitidine absorption, though this is generally not clinically significant when administered with staggered dosing.

Missed dose

If a dose is missed, it should be taken as soon as remembered unless it is nearly time for the next scheduled dose. In that case, the missed dose should be skipped and the regular dosing schedule resumed. Patients should not double the dose to make up for a missed administration. For once-daily regimens, if remembered within 12 hours of the scheduled time, the dose may be taken; otherwise, wait until the next scheduled dose. Maintenance of consistent dosing is important for optimal therapeutic effect, particularly in ulcer healing and GERD management.

Overdose

Symptoms of overdose may include exaggerated pharmacological effects such as bradycardia, hypotension, and gastrointestinal disturbances. In severe cases, respiratory depression and seizures may occur. Management is primarily supportive and symptomatic. Gastric lavage may be considered if ingestion occurred within 1-2 hours. Hemodialysis may be effective in removing ranitidine from circulation, particularly in patients with renal impairment. Cardiac monitoring is recommended in cases of significant overdose. There is no specific antidote for ranitidine overdose. Medical attention should be sought immediately for any suspected overdose.

Storage

Store at room temperature (15-30°C or 59-86°F) in a dry place protected from light and moisture. Keep the container tightly closed. Do not freeze liquid formulations. Tablets should be kept in their original packaging until use. Do not use if the product shows signs of discoloration or deterioration. Keep out of reach of children and pets. Do not transfer tablets to other containers that may not provide adequate protection from moisture. For injection formulations, follow specific storage instructions provided with the product, and do not use if solution appears cloudy or contains particulate matter.

Disclaimer

This information is provided for educational purposes only and does not constitute medical advice. Ranitidine should be used only under the supervision of a qualified healthcare professional. Dosage and treatment duration should be determined based on individual patient characteristics and specific medical conditions. Patients should not discontinue or modify their medication regimen without consulting their healthcare provider. While every effort has been made to ensure accuracy, medical knowledge is constantly evolving, and newer information may supersede the content provided here.

Reviews

Clinical studies have demonstrated ranitidine’s efficacy in healing duodenal ulcers in 70-80% of patients after 4 weeks of therapy. In GERD management, ranitidine provides complete relief of heartburn in approximately 60% of patients after 6 weeks of treatment. Maintenance therapy with ranitidine has shown to reduce ulcer recurrence rates by up to 50% compared to placebo. The medication is generally well-tolerated, with most adverse effects being mild and transient. However, recent concerns regarding potential NDMA contamination have led to increased regulatory scrutiny and market withdrawals in some regions. Many clinicians continue to consider ranitidine an effective option when appropriate quality controls are maintained.