Pepcid AC (Famotidine)


Johnson & Johnsonheart• Merck


Histamine H2 Receptor Antagonist

Action And Clinical Pharmacology: Famotidine is a competitive inhibitor of histamine H2-receptors. The primary clinically important pharmacologic activity of famotidine is inhibition of gastric juice secretion. Famotidine reduces the acid and pepsin content, as well as the volume, of basal, nocturnal, and stimulated gastric secretion.

Pharmacokinetics: Famotidine is incompletely absorbed. The bioavailability of oral doses is 40 to 45%. The bioavailability of the 10 mg chewable tablet was found to be equivalent to the 10 mg film-coated tablet. Bioavailability may be slightly increased by food; however, this effect is of no clinical significance. Bioavailability of Pepcid AC at recommended doses is not affected by customary doses of antacids. Famotidine undergoes minimal first-pass metabolism. After oral doses, peak plasma levels occur in 1 to 3 hours.

A Cmax value of 41 ng/mL and of 40 ng/mL for the 10 mg film-coated and chewable tablet, respectively, was found in 1 bioequivalence study. Plasma levels after multiple doses are similar to those after single doses. Fifteen to 20% of famotidine in plasma is protein bound. Famotidine has an elimination half-life of 2.5 to 3.5 hours. Famotidine is eliminated by renal (65 to 70%) and metabolic (30 to 35%) routes. Renal clearance is 250 to 450 mL/min, indicating some tubular excretion.

Twenty-five to 30% of an oral dose and 65 to 70% of an i.v. dose are recovered in the urine as unchanged compound. The only metabolite identified in man is the S-oxide. There is a close relationship between creatinine clearance values and the elimination half-life of famotidine. In patients with severe renal insufficiency, i.e., creatinine clearance less than 10 mL/min, elimination half-life of famotidine may exceed 20 hours (see Dosage). In elderly patients, there are no clinically significant age-related changes in the pharmacokinetics of famotidine.

Indications And Clinical Uses: The treatment of the following conditions where a controlled reduction of gastric secretion is required, such as acid indigestion, heartburn, sour or upset stomach. It is also indicated for the prevention of these symptoms when associated with the consumption of food and/or beverage.

Contra-Indications: Hypersensitivity to any component of this medication.

Precautions: General: In clinical trials, patients with other underlying acid gastrointestinal diseases (e.g., duodenal ulcer, gastric ulcer) did not experience complications; in general, they did not exhibit a clinically significant deterioration in their condition. However, if patients have difficulty swallowing or if abdominal discomfort persists, the underlying cause should be determined. Symptomatic response to therapy with famotidine does not preclude the presence of gastric malignancy.

Patients with severe kidney disease, previous history of ulcer disease complications, severe coexisting illness, those who are experiencing unintended weight loss in association with dyspeptic symptoms, and those who are middle-aged or older with new or recently changed dyspeptic symptoms should consult a physician before commencing therapy with famotidine.

Patients consuming NSAIDs may have dyspepsia as a side effect of these medicines and should consult a physician or a pharmacist before taking famotidine.

Therapy should not exceed 2 weeks of continuous treatment without medical consultation.

Drug Interactions: Studies with famotidine in man, in animal models, and in vitro have shown no significant interference with the disposition of compounds metabolized by the hepatic microsomal enzymes, e.g., cytochrome P450 system. Compounds tested in man have included warfarin, theophylline, phenytoin, diazepam, aminopyrine and antipyrine. Indocyanine green as an index of hepatic blood flow and/or hepatic drug extraction has been tested and no significant effects have been found.

Concomitant use of aluminum hydroxide/magnesium hydroxide at commonly used doses, does not influence the pharmacodynamics or bioavailability of Pepcid AC. Famotidine does not affect gastric alcohol dehydrogenase and, consequently, blood ethanol levels.

Pregnancy: Reproductive studies have been performed in rats and rabbits at oral doses of up to 2 000 and 500 mg/kg/day, respectively (approximately 2 500 and 625 times the maximum recommended prescription human dose [80 mg], respectively), and have revealed no evidence of impaired fertility or harm to the fetus due to famotidine. There are, however, no adequate or well-controlled studies in pregnant women.

Since the safe use of famotidine in pregnant women has not been established, pregnant women should not use famotidine unless directed otherwise by a physician.

Lactation : Famotidine is detectable in human milk. Nursing mothers should either stop this drug or should stop nursing.

Children: Safety and effectiveness in children have not been established. Pepcid AC should not be administered to children under 12 years of age.

Geriatrics: No dosage adjustment is required based on age (see Pharmacology, Pharmacokinetics).

Adverse Reactions: Famotidine has been demonstrated to be generally well tolerated. Adverse reactions reported in ³1% of patients were headache and dizziness. These occurred with comparable frequency in patients treated with placebo.

Laboratory parameters may be affected during treatment with famotidine, but the changes are usually not considered serious. Among the laboratory changes that were reported during clinical trials were increases in AST, ALT, and WBC count, and decreases in hemoglobin and hematocrit. These changes were rarely of clinical significance.

No famotidine-treated patients/subjects had to be discontinued from therapy because of laboratory adverse experiences.

During marketed use of prescription doses, which are higher than those recommended for nonprescription use, the following adverse reactions have been reported; urticaria, liver enzyme abnormalities, cholestatic jaundice, anaphylaxis, angioedema. Toxic epidermal necrolysis has been reported very rarely with H2-receptor antagonists.

The following adverse reactions have been reported; however, a causal relationship to therapy with famotidine has not been established: agitation, confusion, hallucinations, grand mal seizures, rare cases of impotence, thrombocytopenia, pancytopenia, leukopenia and agranulocytosis.

Gynecomastia has been reported rarely. In most cases that were followed up, it was reversible after discontinuing treatment.

Symptoms And Treatment Of Overdose: Symptoms and Treatment: There is no experience to date with deliberate overdosage. Doses of up to 800 mg/day have been employed in patients with pathological hypersecretory conditions with no serious adverse effects. In the event of overdosage, treatment should be symptomatic and supportive. Unabsorbed material should be removed from the gastrointestinal tract, the patient should be monitored, and supportive therapy should be employed.

The oral LD50 of famotidine in male and female rats and mice was >5 000 mg/kg.

Dosage And Administration: Adults and children 12 years of age or older: 10 mg, as required to relieve symptoms.

For prevention of acid-related symptoms associated with the consumption of food and/or beverage: 10 mg 1 hour before eating. Repeat if symptoms return, up to a maximum of 20 mg in a 24-hour period.

Therapy should not exceed 2 weeks of continuous treatment without medical consultation.

Concomitant Use with Antacids: Antacids may be given concomitantly if needed.

Availability And Storage: Chewable Tablets: Each round, biconvex, pale rose (pink) colored, chewable tablet, with Pepcid AC embossed on one side, contains: famotidine 10 mg. Nonmedicinal ingredients: aspartame, cellulose acetate, citric acid (flavors), hydroxypropyl cellulose, hydroxypropyl methylcellulose, lactose, magnesium stearate, maltodextrin, mannitol, microcrystalline cellulose, modified food starch, red ferric oxide and starch. Boxes of 12 and 30 individually packaged in foil pouches.

Film-coated Tablets: Each rounded-square, pale rose (pink) colored, film-coated tablet, with Pepcid AC embossed on one side, contains: famotidine 10 mg. Nonmedicinal ingredients: hydroxypropyl cellulose, hydroxypropyl methylcellulose, magnesium stearate, microcrystalline cellulose, red ferric oxide, starch, talc and titanium dioxide. Boxes of 6, 12, 18 and 30 individually packaged in PVC/Aluminum blisters.

Store at room temperature (15 to 30°C). Protect from moisture.

PEPCID AC® Johnson & Johnson • Merck Famotidine Histamine H2 Receptor Antagonist

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