FAMOTIDINE

FAMOTIDINE (fa-moe'ti-deen) Pepcid, Pepcid AC Classifications: antisecretory agent (h2-receptor antagonist); Therapeutic: antiulcer; h2-receptor antagonist Prototype: Cimetidine Pregnancy Category: B

Availability

10 mg, 20 mg, 40 mg tablets; 40 mg/5 mL suspension; 10 mg/mL, 20 mg/50 mL injection

Action

A potent competitive inhibitor of histamine at histamine (H₂) receptor sites in gastric parietal cells. Inhibits basal, nocturnal, meal-stimulated, and pentagastrin-stimulated gastric secretion; also inhibits pepsin secretion.

Therapeutic Effect

Reduces parietal cell output of hydrochloric acid; thus, detrimental effects of acid on gastric mucosa are diminished.

Uses

Short-term treatment of active duodenal ulcer. Maintenance therapy for duodenal ulcer patients on reduced dosage after healing of an active ulcer. Treatment of pathologic hypersecretory conditions (e.g., Zollinger-Ellison syndrome), benign gastric ulcer, gastroesophageal reflux disease (GERD), gastritis.

Unlabeled Uses

Stress ulcer prophylaxis.

Contraindications

Hypersensitivity to famotidine or other H₂-receptor antagonists; sudden GI bleeding; lactation.

Cautious Use

Renal insufficiency; renal failure; PKU; hepatic disease; elderly; pregnancy (category B).

Route & Dosage

Duodenal Ulcer Adult: PO 40 mg h.s. or 20 mg b.i.d. PO Maintenance Therapy 20 mg h.s. IV 20 mg q12h Child: PO/IV 0.25–0.5 mg/kg q12h (max: 40 mg/d) Pathological Hypersecretory Conditions Adult: PO 20–160 mg q6h IV 20 mg q6h GERD, Gastritis Adult: PO 10 mg b.i.d. Child: PO 1 mg/kg/d in 2 divided doses (max: 40 mg b.i.d.) Renal Impairment Clcr <50 mL/min: 50% of usual dose or usual dose q36–48h

Administration

Oral

• Give with liquid or food of patient's choice; an antacid may also be given if patient is also on antacid therapy.
• Store at 15°–30° C (59°–86° F). Protect from moisture and strong light; do not freeze.

Intravenous Note: Verify correct IV concentration and rate of infusion/injection with physician before administration to infants or children. PREPARE: Direct: Dilute 20 mg (2 mL) famotidine IV solution (containing 10 mg/mL) with D5W, NS, or other compatible IV diluent (see manufacturer's directions) to a total volume of 5 or 10 mL.  IV Infusion: Dilute 2 mL famotidine IV with 100 mL compatible IV solution.   ADMINISTER: Direct: Give over not less than 2 min.  IV Infusion: Infuse over 15–30 min.   INCOMPATIBILITIES Y-site: Amphotericin B cholesteryl complex, azithromycin, cefepime, piperacillin/tazobactam.

• Store IV solution at 2°–8° C (36°–46° F); reconstituted IV solution is stable for 48 h at room temperature 15°–30° C (59°–86° F).

Adverse Effects (≥1%)

CNS: Dizziness, headache, confusion, depression. GI: Constipation, diarrhea. Skin: Rash, acne, pruritus, dry skin, flushing. Hematologic: Thrombocytopenia. Urogenital: Increases in BUN and serum creatinine.

Interactions

Drug: May inhibit absorption of itraconazole or ketoconazole.

Pharmacokinetics

Absorption: Incompletely from GI tract (40–50% reaches systemic circulation). Onset: 1 h. Peak: 1–3 h PO; 0.5–3 h IV. Duration: 10–12 h. Metabolism: In liver. Elimination: In urine. Half-Life: 2.5–4 h.

Nursing Implications

Assessment & Drug Effects

• Monitor for improvement in GI distress.
• Monitor for signs of GI bleeding.

Patient & Family Education

• Be aware that pain relief may not be experienced for several days after starting therapy.

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Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug