Famotidine

11 DESCRIPTION The active ingredient in famotidine tablets, USP is a histamine-2 (H 2 ) receptor antagonist. Famotidine is N’ -(aminosulfonyl)-3-[[[2-[(diaminomethylene)amino]-4-thiazolyl]methyl] thio]propanimidamide. The empirical formula of famotidine is C 8 H 15 N 7 O 2 S 3 and its molecular weight is 337.45. Its structural formula is: Each famotidine tablet, USP for oral administration contains either 20 mg or 40 mg of famotidine and the following inactive ingredients: corn starch, hypromellose, magnesium stearate, microcrystalline cellulose, sodium starch glycolate and film coating contains carnauba wax, hydroxypropyl cellulose, hypromellose, talc, titanium dioxide; and additionally 20 mg contains iron oxide red and iron oxide yellow. Famotidine, USP is a white to pale yellowish white crystalline powder that is freely soluble in dimethyl formamide, glacial acetic acid, slightly soluble in methanol, very slightly soluble in water, and practically insoluble in acetone, in alcohol, in chloroform, in ether and ethyl acetate. famotabstructure

1 INDICATIONS AND USAGE Famotidine tablets are indicated in adult and pediatric patients 40 kg and greater for the treatment of: • active duodenal ulcer (DU). • active gastric ulcer (GU). • symptomatic nonerosive gastroesophageal reflux disease (GERD). • erosive esophagitis due to GERD, diagnosed by biopsy. Famotidine tablets are indicated in adults for the: • treatment of pathological hypersecretory conditions (e.g., Zollinger-Ellison syndrome, multiple endocrine neoplasias). • reduction of the risk of duodenal ulcer recurrence. Famotidine tablets are a histamine-2 (H 2 ) receptor antagonist indicated ( 1 ): In adult and pediatric patients 40 kg and greater for the treatment of: • active duodenal ulcer (DU). • active gastric ulcer. • symptomatic nonerosive gastroesophageal reflux disease (GERD). • erosive esophagitis due to GERD, diagnosed by biopsy. In adults for the: • treatment of pathological hypersecretory conditions (e.g., Zollinger-Ellison syndrome, multiple endocrine neoplasias). • reduction of the risk of DU recurrence.

4 CONTRAINDICATIONS Famotidine tablets are contraindicated in patients with a history of serious hypersensitivity reactions (e.g., anaphylaxis) to famotidine or other histamine-2 (H 2 ) receptor antagonists. History of serious hypersensitivity reactions (e.g., anaphylaxis) to famotidine or other H 2 receptor antagonists. ( 4 )

5 WARNINGS AND PRECAUTIONS • Central Nervous System (CNS) Adverse Reactions: Elderly patients and patients with renal impairment at increased risk; reduce the dosage. ( 2.2 , 5.1 , 8.5 , 8.6 ) • GI Malignancy: Absence of GI symptoms does not preclude the presence of gastric malignancy; evaluate prior to initiating therapy. ( 5.2 ) 5.1 Central Nervous System Adverse Reactions Central nervous system (CNS) adverse reactions, including confusion, delirium, hallucinations, disorientation, agitation, seizures, and lethargy, have been reported in elderly patients and patients with moderate and severe renal impairment treated with famotidine. Since famotidine blood levels are higher in patients with renal impairment than in patients with normal renal function, dosage adjustments are recommended in patients with renal impairment [see Dosage and Administration ( 2.2 ), Clinical Pharmacology ( 12.3 )]. 5.2 Concurrent Gastric Malignancy In adults, symptomatic response to therapy with famotidine does not preclude the presence of gastric malignancy. Consider evaluation for gastric malignancy in adult patients who have a suboptimal response or an early symptomatic relapse after completing treatment with famotidine.

7 DRUG INTERACTIONS • Drugs Dependent on Gastric pH for Absorption: Systemic exposure of the concomitant drug may be significantly reduced leading to loss of efficacy. See full prescribing information for a list of interacting drugs. ( 7.1 ) • Tizanidine (CYP1A2) Substrate: Potential for substantial increases in blood concentrations of tizanidine resulting in hypotension, bradycardia or excessive drowsiness; avoid concomitant use, if possible. ( 7.2 ) 7.1 Drugs Dependent on Gastric pH for Absorption Famotidine can reduce the absorption of other drugs, due to its effect on reducing intragastric acidity, leading to loss of efficacy of the concomitant drug. Concomitant administration of famotidine with dasatinib, delavirdine mesylate, cefditoren, and fosamprenavir is not recommended. See the prescribing information for other drugs dependent on gastric pH for absorption for administration instructions, including atazanavir, erlotinib, ketoconazole, itraconazole, ledipasvir/sofosbuvir, nilotinib, and rilpivirine. 7.2 Tizanidine (CYP1A2 Substrate) Although not studied clinically, famotidine is considered a weak CYP1A2 inhibitor and may lead to substantial increases in blood concentrations of tizanidine, a CYP1A2 substrate. Avoid concomitant use with famotidine. If concomitant use is necessary, monitor for hypotension, bradycardia or excessive drowsiness. Refer to the full prescribing information for tizanidine.

8.1 Pregnancy Risk Summary Available data with H 2 -receptor antagonists, including famotidine, in pregnant women are insufficient to establish a drug-associated risk of major birth defects, miscarriage or adverse maternal or fetal outcomes. In animal reproduction studies, no adverse development effects were observed with oral administration of famotidine at doses up to approximately 243 and 122 times, respectively, the recommended human dose of 80 mg per day for the treatment of erosive esophagitis (see Data). The estimated background risk for major birth defects and miscarriage for the indicated population is unknown. All pregnancies have a background risk of birth defect, loss, or other adverse outcomes. In the U.S. general population, the background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2 to 4% and 15 to 20%, respectively. Data Animal Data Reproductive studies have been performed in rats and rabbits at oral doses of up to 2000 and 500 mg/kg/day, respectively, and in both species at intravenous doses of up to 200 mg/kg/day, and have revealed no significant evidence of impaired fertility or harm to the fetus due to famotidine. While no direct fetotoxic effects have been observed, sporadic abortions occurring only in mothers displaying marked decreased food intake were seen in some rabbits at oral doses of 200 mg/kg/day (about 49 times the recommended human dose of 80 mg per day, based on body surface area) or higher. There are, however, no adequate or well-controlled studies in pregnant women. Because animal reproductive studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed.

8.4 Pediatric Use The safety and effectiveness of famotidine have been established in pediatric patients for the treatment of peptic ulcer disease (i.e., duodenal ulcer, gastric ulcer) and GERD (i.e., symptomatic nonerosive GERD, erosive esophagitis as diagnosed by endoscopy). The use of famotidine and the recommended dosage of famotidine in these pediatric patients is supported by evidence from adequate and well-controlled studies of famotidine in adults and published pharmacokinetic and pharmacodynamic data in pediatric patients [see Dosage and Administration ( 2.1 ), Clinical Pharmacology ( 12.2 , 12.3 )]. In pediatric patients, the safety and effectiveness for the treatment of pathological hypersecretory conditions and reduction of risk of duodenal ulcer recurrence have not been established. Famotidine 20 and 40 mg tablets are not recommended for use in pediatric patients weighing less than 40 kg because these tablet strengths exceed the recommended dose for these patients [see Dosage and Administration ( 2.1 )]. For pediatric patients weighing less than 40 kg, consider another famotidine formulation (e.g., oral suspension, lower dose tablet).

10 OVERDOSAGE The types of adverse reactions in overdosage of famotidine are similar to the adverse reactions encountered with use of recommended dosages [see Adverse Reactions ( 6.1 )]. 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. Due to low binding to plasma proteins, famotidine is eliminated by hemodialysis. There is limited experience on the usefulness of hemodialysis as a treatment for famotidine overdosage.