Overview
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.
Mechanism of Action
12 CLINICAL PHARMACOLOGY 12.1 Mechanism of Action Famotidine is a competitive inhibitor of histamine-2 (H 2 ) receptors. The primary clinically important pharmacologic activity of famotidine is inhibition of gastric secretion. Both the acid concentration and volume of gastric secretion are suppressed by famotidine, while changes in pepsin secretion are proportional to volume output. 12.2 Pharmacodynamics Adults Famotidine inhibited both basal and nocturnal gastric secretion, as well as secretion stimulated by food and pentagastrin. After oral administration of famotidine, the onset of the antisecretory effect occurred within one hour; the maximum effect was dose-dependent, occurring within one to three hours.
Indications
- 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.
Common Doses
- 40 mg
- 20 mg
- 160 mg
- 60 mL
Dosage
2 DOSAGE AND ADMINISTRATION Indication Recommended Dosage ( 2.1 ) Adult and Pediatric Patients 40 kg and greater Active DU 40 mg once daily; or 20 mg twice daily Active Gastric Ulcer 40 mg once daily GERD 20 mg twice daily Erosive Esophagitis 20 mg twice daily; or 40 mg twice daily Adults Pathological Hypersecretory Conditions 20 mg every 6 hours; adjust to patient needs; maximum 160 mg every 6 hours Risk Reduction of DU Recurrence 20 mg once daily • See full prescribing information for complete dosing information, including dosing in renal impairment, and recommended treatment duration. ( 2.
Contraindications
- 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 )
Side Effects
- 6 ADVERSE REACTIONS The most common adverse reactions are: headache, dizziness, constipation, and diarrhea. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Annora Pharma Private Limited at 1-866-495-1995 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch. 6.1 Clinical Trial Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.
Interactions
- 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.