Class and Category
Pharmacologic Class: Histamine-2 blocker
Therapeutic Class: Antiulcer agent
Indications and Dosages
To provide short-term treatment of active duodenal ulcer
ORAL SUSPENSION
Adults
40 mg daily at bedtime or 20 mg twice daily up to 8 wk.
TABLETS
Adults and children weighing 40 kg (88 lb) or greater
40 mg once daily at bedtime or 20 mg twice daily up to 8 wk.
To prevent the recurrence of duodenal ulcer
ORAL SUSPENSION, TABLETS
Adults
20 mg daily at bedtime up to 1 yr.
To provide short-term treatment for active, benign gastric ulcer
ORAL SUSPENSION
Adults
40 mg daily at bedtime up to 8 wk.
TABLETS
Adults and children weighing 40 kg (88 lb) or more
40 mg daily at bedtime up to 8 wk.
To treat gastroesophageal reflux disease (GERD)
ORAL SUSPENSION
Adults
20 mg twice daily for up to 6 wk.
Children ages 1 to 17
1 mg/kg daily in divided doses twice daily for 6 to 12 wk.
Maximum: 40 mg daily.
Infants age 3 months to 1 year
0.5 mg/kg twice daily for up to 8 wk, increased to 1 mg/kg twice daily, if needed. Maximum: 40 mg/day.
Infants age less than 3 months
0.5 mg/kg once daily for up to 8 wk, increased to 1 mg/kg once daily, as needed.
To treat symptomatic non-erosive GERD
TABLETS
Adults and children weighing 40 kg (88 lb) or more
20 mg twice daily up to 6 wk.
To treat erosive esophagitis caused by gastroesophageal reflux
ORAL SUSPENSION
Adults
20 to 40 mg twice daily for up to 12 wk.
To treat erosive esophagitis due to GERD diagnosed by endoscopy
ORAL SUSPENSION
Adults
20 or 40 mg twice daily for up to 12 wk.
TABLETS
Adults and children weighing 40 kg (88 lb) or more
20 or 40 mg twice daily for up to 12 wk.
To treat pediatric peptic ulcer disease
ORAL SUSPENSION, TABLETS
Children age 1 to 17 years
Initial: 0.5 mg/kg once daily or 0.25 mg/kg twice daily for 8 wk, increased to 1 mg/kg once daily at bedtime or 0.5 mg/kg twice daily, as needed. Maximum: 40 mg/day.
To treat gastric hypersecretory conditions
ORAL SUSPENSION, TABLETS
Adults
Initial: 20 mg every 6 hr. Dosage adjusted, if needed, based on patient response. Maximum: 160 mg every 6 hr.
To treat hospitalized patients with intractable ulcers or pathological hypersecretory conditions; to treat patients who are unable to take oral medication
I.V. INFUSION OR INJECTION
Adults
20 mg every 12 hr, infused over 15 to 30 min or injected over at least 2 min.
Children ages 1 to 16
Initial: 0.25 mg/kg every 12 hr, infused over 15 to 30 min or injected over at least 2 min. Maximum: 40 mg daily.
To prevent heartburn and indigestion
TABLETS
Adults
10 mg 1 hr before eating. Maximum: 20 mg every 24 hr for up to 2 wk.
To treat heartburn and indigestion
TABLETS
Adults
10 mg at the onset of symptoms. Maximum: 20 mg every 24 hr for up to 2 wk unless prescribed otherwise.
DOSAGE ADJUSTMENT Oral or parenteral dosage reduced or dosing interval increased (to 48 hr), if needed, in patients with renal insufficiency and creatinine clearance less than 60 ml/min.
|
Route |
Onset |
Peak |
Duration |
|
P.O. |
1 hr |
1–4 hr |
10–12 hr |
|
I.V. |
In 30 min |
0.5–3 hr |
10–12 hr |
Mechanism of Action
In normal digestion, parietal cells in the gastric epithelium secrete hydrogen (H+) ions, which combine with chloride ions (Cl−) to form hydrochloric acid (HCl), as shown below left. However, HCl can inflame, ulcerate, and perforate gastric and intestinal mucosa normally protected by mucus.
Famotidine, an H2-receptor antagonist, reduces HCl formation by preventing histamine from binding with H2 receptors on the surface of parietal cells, as shown below right. By doing so, the drug helps prevent peptic ulcers from forming and helps heal existing ones.
Contraindications
Hypersensitivity to famotidine, other H2-receptor antagonists, or their components.
Interactions
DRUGS
Drugs dependent on gastric pH for absorption: Reduced absorption of these drugs.
Tizanidine: A possibly substantial increase in blood tizanidine levels with an increased risk of adverse reactions
Adverse Reactions
- CNS: Agitation (infants), anxiety, asthenia, confusion, delirium, depression, dizziness, fatigue, fever, hallucinations, headache, insomnia, lethargy, mental or mood changes, paresthesia, seizures, somnolence
- CV: Arrhythmias, AV block, palpitations, prolonged QT interval
- EENT: Dry mouth, laryngeal edema, taste alteration, tinnitus
- GI: Abdominal pain, anorexia, cholestatic jaundice, constipation, diarrhea, elevated liver enzymes, hepatitis, jaundice, nausea, vomiting
- GU: Decreased libido, impotence
- HEME: Agranulocytosis, aplastic anemia, leukopenia, neutropenia, pancytopenia, thrombocytopenia
- MS: Arthralgia, muscle cramps, musculoskeletal pain, rhabdomyolysis
- RESP: Bronchospasm, dyspnea, interstitial pneumonia, wheezing
- SKIN: Acne, alopecia, dry skin, erythema multiforme, exfoliative dermatitis, flushing, pruritus, rash, Stevens-Johnson syndrome, toxic epidermal necrolysis, urticaria
- Other: Anaphylaxis, angioedema, hyperuricemia
Childbearing Considerations
PREGNANCY
- It is not known if a drug causes fetal harm.
- Use with caution only if benefit to mother outweighs potential risk to fetus.
LACTATION
- The drug is present in breast milk.
- The patient should check with the prescriber before breastfeeding.
Nursing Considerations
- Shake famotidine oral suspension vigorously for 5 to 10 seconds before administration.
- Dilute injection form (2 ml) with normal saline solution or other solution to 5 to 10 ml; give I.V. injection over at least 2 minutes. Or, dilute in 100 ml of D5W and infuse over 15 to 30 minutes, or infuse premixed injection (20 mg/50 ml normal saline solution) over 15 to 30 minutes.
WARNING: Be aware that Pepcid AC chewable tablets contain aspartame, which can be dangerous for patients who have phenylketonuria.
- Know that adult patients who have a suboptimal response or an early symptomatic relapse after completing famotidine therapy should be evaluated for gastric malignancy.
PATIENT TEACHING
- Instruct patient to store famotidine oral suspension at room temperature (below 86° F [30° C]) and to protect it from freezing. Tell her to shake the bottle vigorously, right before use, for 5 to 10 seconds.
- Instruct patient to carefully chew chewable tablets thoroughly before swallowing.
- Instruct patient who also takes antacids to wait 30 to 60 minutes after taking famotidine, if possible, before taking an antacid.
- Caution patient is to avoid alcohol and smoking during famotidine therapy because they irritate the stomach and can delay ulcer healing.
- Advise patient to notify prescriber if she develops pain, has trouble swallowing, or if she has bloody vomit or black stools.
- Caution patient is not to take famotidine with other acid-reducing products.
- Caution patients, especially the elderly and patients with renal impairment, to avoid hazardous activities until the drug’s CNS effects are known.
Tags
Drug