RANITIDINE

Ranitidine hydrochloride (HCl) USP, is a histamine H 2 -receptor antagonist. Chemically it is N-[2-[[[5-[(Dimethylamino)methyl]-2-furanyl]methyl]thio]ethyl]-N’-methyl-2-nitro-1,1-ethenediamine,hydrochloride. It has the following structure: The empirical formula is C 13 H 22 N 4 O 3 S • HCl, representing a molecular weight of 350.8. Ranitidine HCl is a white to pale yellow crystalline, practically odorless powder. Very soluble in water, sparingly soluble in alcohol. Each capsule, for oral administration contains 168 mg or 336 mg of ranitidine hydrochloride equivalent to 150 mg and 300 mg of ranitidine, respectively. Inactive ingredients: Silicon dioxide, corn starch, magnesium stearate, and sodium starch glycolate Type A corn. Each hard-gelatin capsule contains gelatin, titanium dioxide, FD&C Blue no. 1, FD&C Red no. 40, and FD&C Yellow no. 6. Imprinting ink contains: shellac, propylene glycol, ferrosoferric oxide and potassium hydroxide. structure

Ranitidine capsules are indicated in: Short-term treatment of active duodenal ulcer. Most patients heal within 4 weeks. Studies available to date have not assessed the safety of ranitidine in uncomplicated duodenal ulcer for periods of more than 8 weeks. Maintenance therapy for duodenal ulcer patients at reduced dosage after healing of acute ulcers. No placebo-controlled comparative studies have been carried out for periods of longer than 1 year. The treatment of pathological hypersecretory conditions (e.g., Zollinger-Ellison syndrome and systemic mastocytosis). Short-term treatment of active, benign gastric ulcer. Most patients heal within 6 weeks and the usefulness of further treatment has not been demonstrated. Studies available to date have not assessed the safety of ranitidine in uncomplicated, benign gastric ulcer for periods of more than 6 weeks. Maintenance therapy for gastric ulcer patients at reduced dosage after healing of acute ulcers. Placebo-controlled studies have been carried out for 1 year. Treatment of GERD. Symptomatic relief commonly occurs within 24 hours after starting therapy with ranitidine 150 mg two times a day. Treatment of endoscopically diagnosed erosive esophagitis. Symptomatic relief of heartburn commonly occurs within 24 hours of therapy initiation with ranitidine 150 mg 4 times daily. Maintenance of healing of erosive esophagitis. Placebo-controlled trials have been carried out for 48 weeks. Concomitant antacids should be given as needed for pain relief to patients with active duodenal ulcer; active, benign gastric ulcer; hypersecretory states; GERD; and erosive esophagitis.

Active Duodenal Ulcer The current recommended adult oral dosage of ranitidine for duodenal ulcer is 150 mg twice daily. An alternative dosage of 300 mg once daily after the evening meal or at bedtime can be used for patients in whom dosing convenience is important. The advantages of one treatment regimen compared to the other in a particular patient population have yet to be demonstrated (see CLINICAL PHARMACOLOGY: Clinical Trials: Active Duodenal Ulcer ). Smaller doses have been shown to be equally effective in inhibiting gastric acid secretion in US studies, and several foreign trials have shown that 100 mg twice daily is as effective as the 150 mg dose. Antacid should be given as needed for relief of pain (see CLINICAL PHARMACOLOGY: Pharmacokinetics ). Maintenance of Healing of Duodenal Ulcers The current recommended adult oral dosage is 150 mg at bedtime. Pathological Hypersecretory Conditions (such as Zollinger-Ellison syndrome) The current recommended adult oral dosage is 150 mg twice a day. In some patients it may be necessary to administer ranitidine 150 mg doses more frequently. Dosages should be adjusted to individual patient needs, and should continue as long as clinically indicated. Dosages up to 6 g/day have been employed in patients with severe disease. Benign Gastric Ulcer The current recommended adult oral dosage is 150 mg twice a day. Maintenance of Healing of Gastric Ulcers The current recommended adult oral dosage is 150 mg at bedtime. GERD The current recommended adult oral dosage is 150 mg twice a day. Erosive Esophagitis The current recommended adult oral dosage is 150 mg four times a day. Maintenance of Healing of Erosive Esophagitis The current recommended adult oral dosage is 150 mg twice a day. Pediatric Use The safety and effectiveness of ranitidine has been established in the age-group of 1 month to 16 years. There is insufficient information about the pharmacokinetics of ranitidine in neonatal patients (less than 1 month of age) to make dosing recommendations. The following 3 subsections provide dosing information for each of the pediatric indications. Treatment of Duodenal and Gastric Ulcers The recommended oral dose for the treatment of active duodenal and gastric ulcers is 2 mg/kg to 4 mg/kg twice daily to a maximum of 300 mg/day. This recommendation is derived from adult clinical studies and pharmacokinetic data in pediatric patients. Maintenance of Healing of Duodenal and Gastric Ulcers The recommended oral dose for the maintenance of healing of duodenal and gastric ulcers is 2 mg/kg to 4 mg/kg once daily to a maximum of 150 mg/day. This recommendation is derived from adult clinical studies and pharmacokinetic data in pediatric patients. Treatment of GERD and Erosive Esophagitis Although limited data exist for these conditions in pediatric patients, published literature supports a dosage of 5 mg/kg to 10 mg/kg per day, usually given as two divided doses. Dosage Adjustment for Patients with Impaired Renal Function On the basis of experience with a group of subjects with severely impaired renal function treated with ranitidine, the recommended dosage in patients with a creatinine clearance <50 mL/min is 150 mg every 24 hours. Should the patient’s condition require, the frequency of dosing may be increased to every 12 hours or even further with caution. Hemodialysis reduces the level of circulating ranitidine. Ideally, the dosing schedule should be adjusted so that the timing of a scheduled dose coincides with the end of hemodialysis. Elderly patients are more likely to have decreased renal function, therefore caution should be exercised in dose selection, and it may be useful to monitor renal function (see CLINICAL PHARMACOLOGY: Pharmacokinetics: Geriatrics and PRECAUTIONS: Geriatric Use ).

Ranitidine is contraindicated in patients known to have hypersensitivity to the drug or any of the ingredients (see PRECAUTIONS ).

The following have been reported as events in clinical trials or in the routine management of patients treated with ranitidine. The relationship to therapy with ranitidine has been unclear in many cases. Headache, sometimes severe, seems to be related to administration of ranitidine. Central Nervous System Rarely, malaise, dizziness, somnolence, insomnia, and vertigo. Rare cases of reversible mental confusion, agitation, depression, and hallucinations have been reported, predominantly in severely ill elderly patients. Rare cases of reversible blurred vision suggestive of a change in accommodation have been reported. Rare reports of reversible involuntary motor disturbances have been received. Cardiovascular As with other H2-blockers, rare reports of arrhythmias such as tachycardia, bradycardia, atrioventricular block, and premature ventricular beats. Gastrointestinal Constipation, diarrhea, nausea/vomiting, abdominal discomfort/pain, and rare reports of pancreatitis. Hepatic There have been occasional reports of hepatocellular, cholestatic, or mixed hepatitis, with or without jaundice. In such circumstances, ranitidine should be immediately discontinued. These events are usually reversible, but in rare circumstances death has occurred. Rare cases of hepatic failure have also been reported. In normal volunteers, SGPT values were increased to at least twice the pretreatment levels in 6 of 12 subjects receiving 100 mg 4 times daily intravenously for 7 days, and in 4 of 24 subjects receiving 50 mg intravenously 4 times daily for 5 days. Musculoskeletal Rare reports of arthralgias and myalgias. Hematologic Blood count changes (leukopenia, granulocytopenia, and thrombocytopenia) have occurred in a few patients. These were usually reversible. Rare cases of agranulocytosis, pancytopenia, sometimes with marrow hypoplasia, and aplastic anemia and exceedingly rare cases of acquired immune hemolytic anemia have been reported. Endocrine Controlled studies in animals and man have shown no stimulation of any pituitary hormone by ranitidine and no antiandrogenic activity, and cimetidine-induced gynecomastia and impotence in hypersecretory patients have resolved when ranitidine has been substituted. However, occasional cases of impotence and loss of libido have been reported in male patients receiving ranitidine, but the incidence did not differ from that in the general population. Rare cases of breast symptoms and conditions, including galactorrhea and gynecomastia, have been reported in both males and females. Integumentary Rash, including rare cases of erythema multiforme. Rare cases of alopecia and vasculitis. Respiratory A large epidemiological study suggested an increased risk of developing pneumonia in current users of histamine-2-receptor antagonists (H 2 RAs) compared to patients who had stopped H 2 RA treatment, with an observed adjusted relative risk of 1.63 (95% CI, 1.07-2.48). However, a causal relationship between use of H 2 RAs and pneumonia has not been established. Other Rare cases of hypersensitivity reactions (e.g., bronchospasm, fever, rash, eosinophilia), anaphylaxis, angioneurotic edema, acute interstitial nephritis, and small increases in serum creatinine.

Ranitidine has been reported to affect the bioavailability of other drugs through several different mechanisms such as competition for renal tubular secretion, alteration of gastric pH, and inhibition of cytochrome P450 enzymes. Procainamide: Ranitidine, a substrate of the renal organic cation transport system, may affect the clearance of other drugs eliminated by this route. High doses of ranitidine (e.g., such as those used in the treatment of Zollinger-Ellison syndrome) have been shown to reduce the renal excretion of procainamide and N-acetylprocainamide resulting in increased plasma levels of these drugs. Although this interaction is unlikely to be clinically relevant at usual ranitidine doses, it may be prudent to monitor for procainamide toxicity when administered with oral ranitidine at a dose exceeding 300 mg per day. Warfarin: There have been reports of altered prothrombin time among patients on concomitant warfarin and ranitidine therapy. Due to the narrow therapeutic index, close monitoring of increased or decreased prothrombin time is recommended during concurrent treatment with ranitidine. Ranitidine may alter the absorption of drugs in which gastric pH is an important determinant of bioavailability. This can result in either an increase in absorption (e.g., triazolam, midazolam, glipizide) or a decrease in absorption (e.g., ketoconazole, atazanavir, delavirdine, gefitinib). Appropriate clinical monitoring is recommended. Atazanavir: Atazanavir absorption may be impaired based on known interactions with other agents that increase gastric pH. Use with caution. See atazanavir label for specific recommendations. Delavirdine: Delavirdine absorption may be impaired based on known interactions with other agents that increase gastric pH. Chronic use of H 2 -receptor antagonists with delavirdine is not recommended. Gefitinib: Gefitinib exposure was reduced by 44% with the coadministration of ranitidine and sodium bicarbonate (dosed to maintain gastric pH above 5.0). Use with caution. Glipizide: In diabetic patients, glipizide exposure was increased by 34% following a single 150-mg dose of oral ranitidine. Use appropriate clinical monitoring when initiating or discontinuing ranitidine. Ketoconazole: Oral ketoconazole exposure was reduced by up to 95% when oral ranitidine was coadministered in a regimen to maintain a gastric pH of 6 or above. The degree of interaction with usual dose of ranitidine (150 mg twice daily) is unknown. Midazolam: Oral midazolam exposure in 5 healthy volunteers was increased by up to 65% when administered with oral ranitidine at a dose of 150 mg twice daily. However, in another interaction study in 8 volunteers receiving intravenous midazolam, a 300 mg oral dose of ranitidine increased midazolam exposure by about 9%. Monitor patients for excessive or prolonged sedation when ranitidine is coadministered with oral midazolam. Triazolam: Triazolam exposure in healthy volunteers was increased by approximately 30% when administered with oral ranitidine at a dose of 150 mg twice daily. Monitor patients for excessive or prolonged sedation.