Cimetidine
Mechanism :
Cimetidine competitively inhibits the action of histamine at the histamine H2 receptors of the parietal cells and thus is a histamine H2-receptor antagonist. Cimetidine contains an imidazole ring and is chemically related to histamine.
Indication :
- Esophagitis
- Peptic ulcer, Duodenal ulcer
- Zollinger Ellison syndrome
- GERD
- GI bleed
Contraindications :
Cimetidine is contraindicated for patients known to have hypersensitivity to the product.
Dosing :
Neonates:
5-10 mg/kg/day PO 8-12 hourly.
1 month-1 year:
10-20 mg/kg/day PO 6-12 hourly.
1-18 years:
20-40 mg/kg/day PO 6 hourly. Max: 1600 mg/day.
Adverse Effect :
Diarrhea, headache, tiredness, gynecomastia, hepatitis, rash, dry skin, seborrheic dermatitis, erythema annulare centrifugum, erythema multiforme, Stevens-Johnson syndrome, exfoliative dermatitis, toxic epidermal necrolysis, reversible alopecia.
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 | 50% of normal dose |
| <10 | 50% 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 | Not dialysed. 300 mg every 8 hours |
Hepatic Dose :
Use a reduced dose in severe hepatic impairment.