famotidine

famotidine

(fa moe' ti deen)

Apo-Famotidine (CAN), Pepcid, Pepcid AC, Pepcid AC Maximum Strength, Pepcid RPD

Pregnancy Category B

Drug class

Histamine 2 (H₂) receptor antagonist

Therapeutic actions

Competitively blocks the action of histamine at the histamine (H₂) receptors of the parietal cells of the stomach; inhibits basal gastric acid secretion and chemically induced gastric acid secretion.

Indications

·        Short-term treatment and maintenance of duodenal ulcer

·        Short-term treatment of benign gastric ulcer

·        Treatment of pathologic hypersecretory conditions (eg, Zollinger-Ellison syndrome)

·        Short-term treatment of GERD, esophagitis due to GERD

·        OTC: Relief of symptoms of heartburn, acid indigestion, sour stomach

Contraindications and cautions

·        Contraindicated with allergy to famotidine; renal failure; lactation.

·        Use cautiously with pregnancy, renal or hepatic dysfunction.

Available forms

Tablets—10, 20, 40 mg; chewable tablets—10 mg; orally disintegrating tablets—20, 40 mg; gelcaps—10 mg; powder for oral suspension—40 mg/5 mL; injection—10 mg/mL; injection, premixed—20 mg/50 mL in 0.9% sodium chloride

Dosages

ADULTS

·        Acute treatment of active duodenal ulcer: 40 mg PO or IV hs or 20 mg bid PO or IV. Therapy at full dosage should generally be discontinued after 6–8 wk.

·        Maintenance therapy for duodenal ulcer: 20 mg PO hs.

·        Benign gastric ulcer: 40 mg PO daily hs.

·        Hypersecretory syndrome: 20 mg q 6 hr PO initially. Doses up to 160 mg q 6 hr have been administered. 20 mg IV q 12 hr in patients unable to take oral drugs.

·        GERD: 20 mg bid PO for up to 6 wk. For patients with esophagitis, the dose is 20–40 mg bid PO for up to 12 wk.

·        Heartburn, acid indigestion: 10 mg PO for relief; 10 mg PO 1 hr before eating for prevention. Do not exceed 20 mg/24 hr.

PEDIATRIC PATIENTS 1–16 YR

·        Peptic ulcer: 0.5 mg/kg/day PO hs or divided in two doses up to 40 mg/day; 0.25 mg/kg q 12 hr IV up to 40 mg/day.

·        GERD with or without esophagitis: 1 mg/kg/day PO divided in two doses up to 40 mg bid.

GERIATRIC PATIENTS OR PATIENTS WITH RENAL IMPAIRMENT

Reduce dosage to 20 mg PO hs or 40 mg PO q 36–48 hr.

Pharmacokinetics

Route	Onset	Peak	Duration
Oral	Slow	1–3 hr	6–12 hr
IV	< 1 hr	0.5–3 hr	8–15 hr

Metabolism: Hepatic; T_1/2: 2.5–3.5 hr

Distribution: Crosses placenta; enters breast milk

Excretion: Urine

IV facts

Preparation: For direct injection, dilute 2 mL (solution contains 10 mg/mL) with 0.9% sodium chloride injection, water for injection, 5% or 10% dextrose injection, lactated Ringer’s injection, or 5% sodium bicarbonate injection to a total volume of 5–10 mL. For infusion, 2 mL diluted with 100 mL 5% dextrose solution or other IVs. Stable for 48 hr at room temperature, 14 days if refrigerated.

Infusion: Inject directly slowly, over not less than 2 min. Infuse over 15–30 min; continuous infusion: 40 mg/24 hr.

Adverse effects

·        CNS: Headache, malaise, dizziness, somnolence, insomnia

·        Dermatologic: Rash

·        GI: Diarrhea, constipation, anorexia, abdominal pain

·        Other: Muscle cramp, increase in total bilirubin, sexual impotence

Nursing considerations

Assessment

·        History: Allergy to famotidine; renal failure; lactation, pregnancy, hepatic impairment

·        Physical: Skin lesions; liver evaluation, abdominal examination, normal output; renal function tests, serum bilirubin

Interventions

·        If using one dose a day, administer drug hs.

·        Decrease doses with renal failure.

·        Arrange for administration of concurrent antacid therapy to relieve pain.

·        Reserve IV use for hospitalized patients not able to take oral medications; switch to oral medication as soon as possible.

Teaching points

·        Take this drug at bedtime (or in the morning and at bedtime). Therapy may continue for 4–6 weeks or longer. Place rapidly disintegrating tablet on tongue and swallow with or without water.

·        Take antacid exactly as prescribed, being careful of the times of administration.

·        Have regular medical follow-up while using this drug to evaluate your response.

·        Take over-the-counter drug 1 hour before eating to prevent indigestion. Do not take more than two per day.

·        You may experience these side effects: Constipation or diarrhea; loss of libido or impotence (reversible); headache (adjust lights, temperature, noise levels).

·        Report sore throat, fever, unusual bruising or bleeding, severe headache, muscle or joint pain.

Adverse effects in Italic are most common; those in Bold are life-threatening.