Ranitidine
Mechanism :
Ranitidine is a competitive, reversible inhibitor of the action of histamine at the histamine H2-receptors, including receptors on the gastric cells. Ranitidine does not lower serum Ca++ in hypercalcemic states and is not an anticholinergic agent.
Indication :
- Gastric ulcer
- Gastritis
- Hyperacidity
- GERD
- Erosive Esophagitis
Contraindications :
Ranitidine is contraindicated for patients known to have hypersensitivity to the drug or any of the ingredients.
Acute porphyria, Treatment with ranitidine may mask the symptoms of other gastric disease, Raised liver enzymes may occur with high doses.
Dosing :
Active Duodenal or Gastric ulcer:
1 month-16 years:
For treatment: 4-8 mg/kg PO twice daily. Maximum: 300 mg/day.
For maintenance: 2-4 mg/kg PO once daily. Maximum: 150 mg/day.
IV:
2-4 mg/kg/day IV in 6-8 hourly divided doses. Maximum: 50 mg/dose or 200 mg/day.
GERD or Erosive Esophagitis:
Term Neonates: 2-4 mg/kg/day PO in 8-12 hourly divided doses or 2 mg/kg/day IV in 8 hourly divided doses.
1 month-16 years: Oral: 5-10 mg/kg/day PO divided into twice daily doses. Maximum: 300 mg/day.
IV:
2-4 mg/kg/day IV in 6-8 hourly divided doses; Maximum: 50 mg/dose or 200 mg/day; alternatively, 1 mg/kg/dose infusion once followed by 2-4 mg/kg/day continuous infusion.
Stress ulceration (Prophylaxis):
2 mg/kg twice daily or 1.5 mg/kg IV thrice daily; alternatively, 2 mg/kg over 10 mins followed by 0.083 mg/kg/hour continuous infusion.
Adverse Effect :
Hypersensitivity reactions, including urticaria, angioneurotic edema, fever, bronchospasm, hypotension and anaphylaxis have been reported.
Interaction :
Warfarin-type Anticoagulants, Phenytoin, Propranolol, Nifedipine, Chlordiazepoxide, Diazepam, Certain Tricyclic Antidepressants, Lidocaine, Theophylline and Metronidazole: Increases metabolism of these drugs.
Ketoconazole: Alteration of pH may affect absorption.
Renal Dose :
Dose in Renal Impairment GFR (mL/min)
| 20-50 | Dose as in normal renal function |
| 10-20 | Dose as in normal renal function |
| <10 | 50–100% of normal dose |
Dose in Patients undergoing Renal Replacement Therapies
| CAPD | Not dialysed. Dose as in GFR<10 mL/min |
| HD | Dialysed. Dose as in GFR<10 mL/ min |
| HDF/High flux | Dialysed. Dose as in GFR<10 mL/ min |
| CAV/VVHD | Probably dialysed. 50 mg every 8–12 hours. Oral: dose as in normal renal function |
Hepatic Dose :
No dosage adjustments are recommended.