Cimetidine (Tagamet) inhibits the action of histamine at the histamine2 (H2) receptors of the stomach, inhibiting gastric acid secretion and reducing total pepsin output.
Brand Names
- Tagamet
- Tagamet HB, Tagamet HB Suspension
Drug class
- Histamine2 (H2) antagonist
- Pregnancy Category B
Therapeutic actions
Inhibits the action of histamine at the histamine2 (H2) receptors of the stomach, inhibiting gastric acid secretion and reducing total pepsin output.
Indications
- Short-term treatment of active duodenal ulcer
- Short-term treatment of benign gastric ulcer
- Treatment of pathologic hypersecretory conditions (Zollinger-Ellison syndrome)
- Prophylaxis of stress-induced ulcers and acute upper GI bleeding in critical patients
- Treatment of erosive GERD
- OTC use: Relief of symptoms of heartburn, acid indigestion, sour stomach
Contraindications and Cautions
- Contraindicated with allergy to cimetidine.
- Use cautiously with impaired renal or hepatic function, lactation.
Available Forms
Tablets—100, 200, 300, 400, 800 mg; liquid—300 mg/5 mL; injection—150 mg/mL, 300 mg/2 mL
Dosages
ADULTS
- Active duodenal ulcer: 800 mg PO hs or 300 mg PO qid at meals and hs or 400 mg PO bid; continue for 4–6 wk. For intractable ulcers, 300 mg IM or IV q 6–8 hr.
- Maintenance therapy for duodenal ulcer: 400 mg PO hs.
- Active gastric ulcer: 300 mg PO qid at meals and hs or 800 mg hs.
- Pathologic hypersecretory syndrome: 300 mg PO qid at meals and hs, or 300 mg IV or IM q 6 hr. Individualize doses as needed; do not exceed 2,400 mg/day.
- Erosive GERD: 1,600 mg PO in divided doses bid–qid for 12 wk.
- Prevention of upper GI bleeding: Continuous IV infusion of 50 mg/hr. Do not treat beyond 7 days (if creatinine clearance < 30 ml/min, give 25 mg/hr).
- Heartburn, acid indigestion: 200 mg as symptoms occur, up to 4 tablets/24 hr.
PEDIATRIC PATIENTS
Not recommended for children < 12 yr.
GERIATRIC PATIENTS OR PATIENTS WITH IMPAIRED RENAL FUNCTION
Accumulation may occur. Use lowest dose possible, 300 mg PO or IV q 12 hr; may be increased to q 8 hr if patient tolerates it and levels are monitored; if creatinine clearance < 30 ml/min, give 25 mg/hr IV for prevention of upper GI bleed.
Adverse Effects
- CNS: Dizziness, somnolence, headache, confusion, hallucinations, peripheral neuropathy; symptoms of brain stem dysfunction (dysarthria, ataxia, diplopia)
- CV: Cardiac arrhythmias, cardiac arrest, hypotension (IV use)
- GI: Diarrhea
- Hematologic: Increases in plasma creatinine, serum transaminase
- Other: Impotence (reversible), gynecomastia (in long-term treatment), rash, vasculitis, pain at IM injection site
Interactions
Drug-drug
- Increased risk of decreased white blood cell counts with antimetabolites, alkylating agents, other drugs known to cause neutropenia
- Increased serum levels and risk of toxicity of warfarin-type anticoagulants, phenytoin, beta-adrenergic blocking agents, alcohol, quinidine, lidocaine, theophylline, chloroquine, certain benzodiazepines (alprazolam,chlordiazepoxide, diazepam, flurazepam, triazolam), nifedipine, pentoxifylline, TCAs, procainamide, carbamazepine when taken with cimetidine
Nursing Interventions
- Give drug with meals and hs.
- Administer IM dose undiluted deep into large muscle group.
- Arrange for regular follow-up, including blood tests to evaluate effects.
