📄 H2 antagonists
H2 antagonists inhibit the action of histamine at the H2receptors of the stomach, inhibiting gastric acid secretion and reducing total pepsin output; the resultant decrease in acid allows healing of ulcerated areas.
Indications
Short-term and maintenance treatment of active duodenal ulcer and benign gastric ulcer Treatment of pathologic hypersecretory conditions (Zollinger-Ellison syndrome) and erosive GERD Prophylaxis of stress-induced ulcers and acute upper GI bleed in critically ill patients Treatment of GERD, heartburn, acid indigestion, sour stomach Contraindications and cautions
Contraindicated with allergy to H2antagonists, impaired renal or hepatic function, or lactation. Adverse effects
CNS: Dizziness, somnolence, headache, confusion, hallucinations, peripheral neu- ropathy, symptoms of brain stem dysfunction (dysarthria, ataxia, diplopia) CV: Cardiac arrhythmias, arrest; hypotension (IV use) GI: Diarrhea Hematologic: Increases in plasma creatinine, serum transaminase Adverse effects
in italics are most common; those in bold are life-threatening. U Do not crush. Other: Impotence (reversible with drug withdrawal), gynecomastia (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 blockers, alcohol, quinidine, lidocaine, theophylline, chloroquine, certain benzodiazepines (alprazolam, chlor- diazepoxide, diazepam, flurazepam, triazolam), nifedipine, pentoxifylline, tricyclic antidepressants, procainamide, carbamazepine when taken with H2antagonists Assessment
History: Allergy to H2antagonists, impaired renal or hepatic function, lactation Physical: Skin lesions; orientation, affect; pulse, baseline ECG (continuous with IV use); liver evaluation, abdominal examination, normal output; CBC, LFTs, renal function tests Interventions
Administer drug with food and at bedtime. Decrease doses in renal and hepatic impairment. Administer IM dose undiluted, deep into large muscle group. Ensure ready access to bathroom. Provide comfort measures for rash, headache. Establish safety measures if CNS changes occur (side rails, accompany patient). Arrange for regular follow-up, including liver and renal function tests, to evaluate effects. Teaching points
Take these drugs with food and at bedtime; therapy may continue for 46 weeks or longer. Take antacids exactly as prescribed; be careful of the time. Inform your health care provider about your cigarette smoking habits. Cigarette smoking decreases the effectiveness of these drugs. Have regular medical follow-up while on this drug to evaluate your response. Report sore throat, fever, unusual bruising or bleeding, tarry stools, confusion, hallucinations, dizziness, muscle or joint pain. Representative drugs
cimetidine famotidine nizatidine ranitidine
