Brand name
- Zantac®
Drug Class
- H2 blocker
Preparations
-
Capsule: 150 mg, 300 mg
-
Syrup: 15 mg/mL (5 mL, 10 mL, 120 mL, 473 mL, 480 mL)
Pharmacology
- Competitive inhibition of histamine at H2-receptors of the gastric parietal cells, which inhibits gastric acid secretion, gastric volume, and hydrogen ion concentration are reduced
Metabolism
- Substrate of CYP1A2, CYP2C19, CYP2D6, P-glycoprotein
- Inhibits CYP1A2, 2D6
Dosing
- Duodenal ulcer:
- 150 mg twice daily, or 300 mg once daily after the evening meal or at bedtime
- Eradication of Helicobacter pylori:
- 150 mg twice daily; requires combination therapy
- Pathological hypersecretory conditions:
- 150 mg twice daily
- Zollinger-Ellison:
- Initial: 1 mg/kg/hour
- Maximum: up to 2.5 mg/kg/hour (or 220 mg/hour) is suggested
Drug Interactions
H2-Antagonists may:
- Decrease the absorption of:
- Cefuroxime
- Cefpodoxime
- Atazanavir
- Decrease the serum concentration of:
- Indinavir
- Nelfinavir
- Increase the absorption of:
- Dexmethylphenidate
- Methylphenidate.
- Increase serum concentration of:
- Varenicline
- Warfarin
Adverse Effects
- Cardiovascular:
- Asystole
- atrioventricular block
- bradycardia (with rapid I.V. administration)
- premature ventricular beats
- tachycardia
- vasculitis
- Central nervous system:
- Agitation
- dizziness
- depression
- hallucinations
- headache
- insomnia
- malaise
- mental confusion
- somnolence
- vertigo
- Dermatologic:
- Alopecia
- erythema multiforme
- rash
- Endocrine & metabolic:
- Prolactin levels increased
- Gastrointestinal:
- Abdominal discomfort/pain,
- constipation
- diarrhea
- nausea
- pancreatitis
- vomiting
- Hematologic:
- Acquired immune hemolytic anemia
- acute porphyritic attack
- agranulocytosis
- aplastic anemia
- granulocytopenia
- pancytopenia
- thrombocytopenia
- Hepatic:
- Cholestatic hepatitis
- hepatic failure
- hepatitis
- jaundice
- Neuromuscular & skeletal:
- Arthralgia
- involuntary motor disturbance
- myalgia
- Ocular:
- Blurred vision
- Renal:
- Acute interstitial nephritis
- serum creatinine increased
- Miscellaneous:
- Anaphylaxis
- angioneurotic edema
- hypersensitivity reactions
Contraindications
- Hypersensitivity to ranitidine or any component of the formulation
Pregnancy and Breastfeeding
- Adverse events were not observed in animal studies; therefore, ranitidine is classified as pregnancy category B.
- Ranitidine is excreted into breast milk. The manufacturer recommends that caution be exercised when administering ranitidine to nursing women.
Precautions
- May result in false-positive urine for amphetamine/methamphetamine
Warning
- Vitamin B-12 deficiency: Long-term therapy may be associated with vitamin vitamin B-12 deficiency.
- May rarely cause agranulocytosis; use caution with clozapine and carbamazepine; concurrent use with diazepam may reduce diazepam’s effectiveness
- Reversible confusional states (rare):
- Associated with increased age (>50 years) and renal or hepatic impairment
- Usually clears within 3-4 days after discontinuation
- Use with caution in patients with hepatic impairment
- Avoid use in patients with a history of acute porphyria; may precipitate attacks.
- Use with caution in patients with renal impairment; dosage adjustment recommended.
Section
This document is prepared by the “Mental Health for All” team. This document is provided for information purposes only and does not necessarily represent endorsement by or an official position of the Essentials of Medicine. Advice on the treatment or care of an individual patient should be obtained through consultation with a physician who has examined that patient or is familiar with that patient’s medical history.