ranitidine
Zantac, Zantac 75, Zantac EFFERdose, Zantac GELdose

Available forms
Available by prescription only
Capsules: 150 mg, 300 mg
Granules (effervescent): 150 mg
Injection: 25 mg/ml
Injection (premixed): 50 mg/50 ml
Syrup: 15 mg/ml
Tablets: 150 mg, 300 mg
Tablets (effervescent): 150 mg
Available without a prescription
Tablets: 75 mg

Indications and dosages
 Duodenal and gastric ulcer (short-term treatment); pathologic hypersecretory conditions such as Zollinger-Ellison syndrome. Adults: 150 mg P.O. b.i.d. or 300 mg h.s. Doses up to 6 g daily may be given to patients with Zollinger-Ellison syndrome. For parenteral use, 50 mg I.V. or I.M. q 6 to 8 hours.
Children ages 1 month to 16 years: For treatment of duodenal and gastric ulcers, 2 to 4 mg/kg P.O. b.i.d. Maximum, 300 mg daily.
 Maintenance therapy in duodenal or benign gastric ulcer. Adults: 150 mg P.O. h.s.
Children ages 1 month to 16 years: 2 to 4 mg/kg P.O. once daily. Maximum, 150 mg daily.
 Prevention of stress ulcer. Adults: Continuous I.V. infusion of 150 mg in 250 ml compatible solution delivered at 6.25 mg/hour using an infusion pump.
 Gastroesophageal reflux disease. Adults: 150 mg P.O. b.i.d.
 Erosive esophagitis. Adults: 150 mg or 10 ml (2 teaspoonfuls equivalent to 150 mg of ranitidine) P.O. q.i.d.
 Self-medication for relief of occasional heartburn, acid indigestion, and sour stomach. Adults and adolescents age 12 and older: 75 mg P.O. once or twice daily; maximum, 150 mg in 24 hours.

Pharmacodynamics
Antiulcer action: Ranitidine competitively inhibits the action of histamine at H₂-receptors in gastric parietal cells. This reduces basal and nocturnal gastric acid secretion as well as that caused by histamine, food, amino acids, insulin, and pentagastrin.

Pharmacokinetics
Absorption: About 50% to 60% of an oral dose is absorbed; food doesn’t significantly affect absorption. After I.M. injection, drug is absorbed rapidly from parenteral sites.
Distribution: Distributed to many body tissues and appears in CSF and breast milk. Drug is about 10% to 19% protein-bound.
Metabolism: Metabolized in the liver.
Excretion: Excreted in urine and feces. Half-life is 2 to 3 hours.

Contraindications and precautions
Contraindicated in patients hypersensitive to drug and in those with a history of acute porphyria. Use cautiously in patients with impaired renal or hepatic function.

Interactions
Drug-drug. Antacids: Decreases ranitidine absorption. Give drugs at least 1 hour apart.
Diazepam: Decreases diazepam absorption. Monitor patient closely.
Glipizide: May increase hypoglycemic effect. Adjust glipizide dosage if needed.
Procainamide: Decreases renal clearance of procainamide. Monitor patient closely for toxicity.
Warfarin: May interfere with warfarin clearance. Monitor patient closely.

Adverse reactions
CNS: malaise, vertigo.
EENT: blurred vision.
Hematologic: reversible leukopenia, pancytopenia, granulocytopenia, thrombocytopenia.
Hepatic: jaundice.
Skin: burning and itching at injection site.
Other: anaphylaxis, angioedema.

Effects on lab test results
• May increase creatinine and ALT levels.
• May decrease RBC, WBC, platelet, and granulocyte counts.

Overdose and treatment
No cases of overdose have been reported. However, treatment would involve emesis or gastric lavage and supportive measures as needed. Drug is removed by hemodialysis.

Special considerations
 ALERT Don’t confuse Zantac with Zyrtec.
• When giving drug by I.V. push, dilute to a total volume of 20 ml and inject over 5 minutes. No dilution is needed for I.M. use. Drug also may be given by intermittent I.V. infusion. Dilute 50 mg ranitidine in 100 ml of D₅W and infuse over 15 to 20 minutes.
• Patients with impaired renal function may need dosage adjustment.
• Dialysis removes ranitidine; administer drug after treatment.
• Ranitidine may cause false-positive results in urine protein tests using Multistix.
• Debilitated patients may experience reversible confusion, agitation, depression, and hallucinations.
• Assess patient for abdominal pain. Note presence of blood in emesis, stool, or gastric aspirate.
Breast-feeding patients
• Drug appears in breast milk. Use cautiously in breast-feeding women.
Geriatric patients
• These patients may experience more adverse reactions because of reduced renal clearance.

Patient education
• Instruct patient to take drug as directed, even after pain subsides, to ensure proper healing.
• If patient is taking a single daily dose, advise him to take it at bedtime.
• Instruct patient not to take OTC forms continuously for longer than 2 weeks without medical supervision.
• Tell patient to swallow oral forms whole with water and not to chew tablets.

Reactions may be common, uncommon, life-threatening, or COMMON AND LIFE THREATENING.
◆ Canada only
◇ Unlabeled clinical use