Famotidine

Description

The active ingredient in famotidine tablets USP is a histamine-2 (H2) receptor antagonist. Famotidine is chemically designated as 3-[2-(Diaminomethyleneamino)thiazol-4-ylmethylthio]-N'–Sulfamoylpropanimidamide. Its molecular formula is C8H15N7O2S3, and it has a molecular weight of 337.45. Each famotidine tablet for oral administration contains either 20 mg or 40 mg of famotidine USP. Inactive ingredients include corn starch, hydroxypropyl cellulose, hypromellose, magnesium stearate, microcrystalline cellulose, sodium starch glycolate, and titanium dioxide. The 20 mg tablets also contain iron oxide yellow. Famotidine USP appears as a white to yellowish-white crystalline powder or crystals. It is freely soluble in glacial acetic acid and dimethyl formamide, very slightly soluble in methanol, and practically insoluble in ethanol and ethyl acetate.

Uses and Indications

Famotidine is indicated for the treatment of active duodenal ulcer (DU) in adult and pediatric patients weighing 40 kg and greater. It is also indicated for the management of active gastric ulcer in the same patient population. Additionally, famotidine is indicated for the treatment of symptomatic nonerosive gastroesophageal reflux disease (GERD) and erosive esophagitis due to GERD, both diagnosed by biopsy, in adult and pediatric patients weighing 40 kg and greater.

Furthermore, famotidine is indicated for the treatment of pathological hypersecretory conditions, such as Zollinger-Ellison syndrome and multiple endocrine neoplasias, in adults. It is also indicated for the reduction of the risk of duodenal ulcer recurrence in adults.

There are no specific teratogenic or nonteratogenic effects associated with famotidine.

Dosage and Administration

Adult and pediatric patients weighing 40 kg and greater may be prescribed the following dosages based on their specific condition:

For active duodenal ulcers (DU), the recommended dosage is 40 mg once daily or 20 mg twice daily. In the case of active gastric ulcers, a dosage of 40 mg once daily is advised. For gastroesophageal reflux disease (GERD), the dosage is 20 mg twice daily. Patients with erosive esophagitis may receive either 20 mg twice daily or 40 mg twice daily, depending on the severity of their condition. For pathological hypersecretory conditions, the initial dosage is 20 mg every 6 hours, with adjustments made according to patient needs, not exceeding a maximum of 160 mg every 6 hours. To reduce the risk of recurrence of duodenal ulcers, a dosage of 20 mg once daily is recommended.

Administration of the medication should occur once daily before bedtime or twice daily, with doses taken in the morning and before bedtime. The medication may be taken with or without food, as per the patient's preference.

Contraindications

Use is contraindicated in patients with a history of serious hypersensitivity reactions, including anaphylaxis, to famotidine or other H2 receptor antagonists. This contraindication is due to the potential for severe allergic reactions in susceptible individuals.

Warnings and Precautions

Elderly patients and those with renal impairment are at an increased risk for central nervous system (CNS) adverse reactions. It is recommended that the dosage be reduced in these populations to mitigate potential risks.

Healthcare professionals should be aware that the absence of gastrointestinal (GI) symptoms does not rule out the possibility of gastric malignancy. A thorough evaluation for GI malignancy is advised prior to the initiation of therapy to ensure patient safety and appropriate treatment planning.

Side Effects

Patients receiving famotidine may experience a range of adverse reactions, which can be categorized by frequency and seriousness.

Common adverse reactions reported include headache, dizziness, constipation, and diarrhea. These reactions are generally mild and may not require medical intervention.

Serious adverse reactions have been noted, particularly in patients with a history of serious hypersensitivity reactions, such as anaphylaxis, to famotidine or other H2 receptor antagonists. Additionally, elderly patients and those with renal impairment are at an increased risk for central nervous system (CNS) adverse reactions. It is recommended that the dosage be reduced in these populations to mitigate this risk.

In clinical trials and postmarketing experiences, CNS adverse reactions have been particularly reported among elderly patients, both with and without renal impairment. Given that famotidine is substantially excreted by the kidneys, the risk of adverse reactions may be heightened in elderly patients, especially those with impaired renal function.

In cases of overdosage, the types of adverse reactions observed are similar to those encountered with the use of recommended dosages, underscoring the importance of adhering to prescribed amounts to minimize the risk of adverse effects.

Drug Interactions

There are currently no documented drug interactions associated with this medication. Additionally, there are no known interactions with laboratory tests. As such, no specific recommendations for dosage adjustments or monitoring are warranted at this time.

Packaging & NDC

The table below lists all NDC Code configurations of Famotidine, the U.S. brand-name prescription product. Columns show Packaging, Formulation Type, and Active Ingredient Strength.

Pediatric Use

The safety and effectiveness of famotidine have been established in pediatric patients for the treatment of peptic ulcer disease, including duodenal ulcers, gastric ulcers, and gastroesophageal reflux disease (GERD), which encompasses symptomatic nonerosive GERD and erosive esophagitis as diagnosed by endoscopy. The recommended dosage of famotidine in these pediatric patients is supported by evidence from adequate and well-controlled studies conducted in adults, along with published pharmacokinetic and pharmacodynamic data specific to pediatric populations.

However, the safety and effectiveness of famotidine for the treatment of pathological hypersecretory conditions and for the reduction of the risk of duodenal ulcer recurrence in pediatric patients have not been established. Additionally, famotidine 20 mg and 40 mg tablets are not recommended for use in pediatric patients weighing less than 40 kg, as these tablet strengths exceed the recommended dose for this weight group. For pediatric patients weighing less than 40 kg, alternative formulations of famotidine, such as oral suspension or lower dose tablets, should be considered.

Geriatric Use

Approximately 10% of the 1,442 patients treated with famotidine in clinical studies were aged 65 years and older. These studies did not reveal any overall differences in safety or effectiveness between elderly patients and their younger counterparts. However, caution is warranted when prescribing famotidine to geriatric patients, particularly those with renal impairment, as postmarketing experience has indicated that central nervous system (CNS) adverse reactions have been reported in this population, regardless of renal function status.

Given that famotidine is substantially excreted by the kidneys, the risk of adverse reactions may be heightened in elderly patients, especially those with compromised renal function. Therefore, it is recommended to use the lowest effective dose of famotidine in geriatric patients and to closely monitor renal function throughout the treatment course. This approach will help mitigate potential risks and ensure the safe use of famotidine in the elderly population.

Pregnancy

Available data regarding the use of H2-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 developmental 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.

The estimated background risk for major birth defects and miscarriage in the indicated population is unknown; however, all pregnancies carry a background risk of birth defects, 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 estimated to be 2 to 4% and 15 to 20%, respectively.

Reproductive studies conducted in rats and rabbits at oral doses of up to 2000 and 500 mg/kg/day, respectively, as well as intravenous doses of up to 200 mg/kg/day, 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 were noted in some rabbits that exhibited marked decreased food intake at oral doses of 200 mg/kg/day (approximately 49 times the recommended human dose of 80 mg per day, based on body surface area) or higher.

It is important to note that there are no adequate or well-controlled studies in pregnant women. Given that animal reproductive studies are not always predictive of human response, famotidine should be used during pregnancy only if clearly needed.

Lactation

There are no specific statements regarding the use of this medication in nursing mothers or its effects on lactation. Additionally, there are no known data on the excretion of this medication in breast milk or its effects on breastfed infants. Healthcare professionals should consider the absence of information when advising lactating mothers about the use of this medication.

Renal Impairment

Patients with renal impairment, particularly elderly individuals, are at an increased risk for adverse effects. It is recommended that the dosage be reduced in these patients to mitigate potential risks associated with reduced kidney function. Careful monitoring of renal function is advised to ensure appropriate dosing and to avoid complications.

Hepatic Impairment

Patients with hepatic impairment have not been specifically studied in relation to the use of this medication. Consequently, there are no established dosage adjustments, special monitoring requirements, or precautions outlined for individuals with compromised liver function. It is recommended that healthcare providers exercise caution when prescribing this medication to patients with hepatic impairment, given the lack of data on its safety and efficacy in this population. Regular monitoring of liver function may be prudent in these cases, although specific parameters are not defined in the available information.

Overdosage

In cases of famotidine overdosage, the adverse reactions observed are generally consistent with those experienced at recommended dosages. Symptoms may include gastrointestinal disturbances and other effects typical of famotidine administration.

Management of overdosage should focus on symptomatic and supportive care. It is essential to remove any unabsorbed material from the gastrointestinal tract to mitigate the effects of the overdose. This may involve the use of activated charcoal or other appropriate measures, depending on the clinical scenario.

Continuous monitoring of the patient is crucial, and supportive therapy should be initiated as necessary. Given famotidine's low binding to plasma proteins, it is noteworthy that hemodialysis can facilitate its elimination from the body. However, there is limited clinical experience regarding the efficacy of hemodialysis specifically for famotidine overdosage, and its use should be considered on a case-by-case basis.

Nonclinical Toxicology

The carcinogenic potential of famotidine was evaluated in a 106-week oral carcinogenicity study in rats and a 92-week oral carcinogenicity study in mice. In both studies, conducted at oral doses of up to 2000 mg/kg/day (approximately 243 and 122 times the recommended human dose of 80 mg per day for the treatment of erosive esophagitis), there was no evidence of carcinogenic potential associated with famotidine.

In terms of mutagenicity, famotidine was found to be negative in the microbial mutagen test (Ames test) using Salmonella typhimurium and Escherichia coli, both with and without rat liver enzyme activation, at concentrations up to 10,000 mcg/plate. Additionally, in vivo studies in mice, including a micronucleus test and a chromosomal aberration test, did not demonstrate any evidence of mutagenic effects.

Furthermore, studies involving rats administered oral doses of up to 2000 mg/kg/day (approximately 243 times the recommended human dose) indicated that fertility and reproductive performance were not adversely affected.

Postmarketing Experience

No specific postmarketing experience details are available in the extracted data. As such, there are no additional adverse events or rare case reports to summarize.

Patient Counseling

Healthcare providers should advise elderly patients and those with moderate to severe renal impairment about the potential risk of central nervous system (CNS) adverse reactions associated with the use of famotidine. These reactions may include confusion, delirium, hallucinations, disorientation, agitation, seizures, and lethargy. Patients should be instructed to report any of these symptoms immediately to their healthcare provider.

Additionally, it is important to inform patients with moderate and severe renal impairment about the risk of QT interval prolongation. They should be advised to report any new cardiac symptoms, such as palpitations, fainting, or feelings of dizziness or lightheadedness, to their healthcare provider without delay.

Patients should be instructed on the proper administration of famotidine tablets, which may be taken once daily before bedtime or twice daily, as recommended by their healthcare provider. It is acceptable for famotidine tablets to be taken with or without food, and they may also be administered alongside antacids if needed.

Storage and Handling

The product is supplied in a USP tight, light-resistant container to ensure its integrity and stability. It should be stored at a temperature range of 20° to 25°C (68° to 77°F), in accordance with USP Controlled Room Temperature guidelines. Proper storage conditions are essential to maintain the quality and efficacy of the product.

Additional Clinical Information

No further data are available.

FDA Insert (PDF)

This document is the official FDA-approved prescribing information for Famotidine as submitted by Novadoz Pharmaceuticals LLC. It includes detailed information about indications, dosage, contraindications, warnings, and clinical pharmacology.

View full prescribing information (PDF)