Ranitidine: Uses, Dosage, Side Effects, and More
1. Drug Name
Generic Name: Ranitidine
Brand Name(s):
- Pakistan: Zantac, Rani
- India: Zinetac, Rantac
- United States: Zantac
- United Kingdom: Zantac, Zantac 75
2. Pharmacological Class
Class: H2 Receptor Antagonist
Subclass: Histamine H2 receptor antagonist
3. Mechanism of Action
Ranitidine works by blocking histamine H2 receptors on the parietal cells in the stomach lining. This action reduces the production of stomach acid, helping to alleviate symptoms and promote healing of acid-related conditions.
4. Indications
Primary Indications:
- Gastroesophageal reflux disease (GERD)
- Peptic ulcer disease
- Zollinger-Ellison syndrome
- Erosive esophagitis
- Heartburn
Off-label Uses:
- Prevention of stress ulcers in critically ill patients
- Treatment of urticaria (hives)
5. Dosage and Administration
Standard Dosage:
- GERD: 150 mg twice daily or 300 mg once daily at bedtime.
- Peptic Ulcer Disease: 150 mg twice daily or 300 mg once daily at bedtime for 4-8 weeks.
- Zollinger-Ellison Syndrome: Dosage varies based on patient response, often starting at 150 mg twice daily.
Route of Administration: Oral
Special Populations:
- Pediatric: Dosage should be individualized based on weight and age.
- Geriatric: Dose adjustments may be necessary due to decreased kidney function.
6. Pharmacokinetics
Absorption: Rapidly absorbed, with peak plasma levels occurring within 2-3 hours.
Distribution: Widely distributed, with approximately 15% bound to plasma proteins.
Metabolism: Minimally metabolized in the liver.
Excretion: Primarily excreted in urine (70%), with the remainder in feces.
Half-life: Approximately 2-3 hours.
7. Contraindications
Ranitidine is contraindicated in patients with:
- Hypersensitivity to ranitidine or any of its components.
8. Warnings and Precautions
Use caution in patients with:
- Severe renal impairment
- Severe hepatic impairment
- Porphyria
- Risk factors for pneumonia
Long-term use may be associated with vitamin B12 deficiency.
9. Side Effects
Common Side Effects:
- Headache
- Constipation
- Diarrhea
- Nausea
Serious Side Effects:
- Severe allergic reactions
- Changes in heart rate
- Severe abdominal pain
- Jaundice
10. Drug Interactions
Major Interactions:
- Atazanavir (reduced efficacy)
- Gefitinib (reduced absorption)
Moderate Interactions:
- Warfarin (increased risk of bleeding)
- Midazolam (increased levels)
Minor Interactions:
- Ketoconazole (reduced absorption)
- Glipizide (enhanced hypoglycemic effect)
11. Pregnancy and Lactation
Pregnancy Category: B
Breastfeeding Considerations: Ranitidine is excreted in breast milk. Use only if clearly needed and the benefits outweigh the risks.
12. Patient Counseling Information
Key Points for Patients:
- Take ranitidine exactly as prescribed.
- Do not take double doses if a dose is missed; take the next dose at the regular time.
- Avoid alcohol as it can increase the risk of stomach damage.
- Report any signs of allergic reactions, severe side effects, or unusual symptoms to your healthcare provider.
Administration Tips:
- Can be taken with or without food.