Famotidine

Description

The active ingredient in famotidine for oral suspension, USP, is a histamine-2 (H2) receptor antagonist. Famotidine, USP is chemically defined as propanimidamide, N'-(aminosulfonyl)-3-[[[2-(diaminomethylene)amino-4-thiazolyl]methyl]thio] with an empirical formula of C8H15N7O2S3 and a molecular weight of 337.45.

Each 5 mL dose of famotidine for oral suspension, USP, when prepared as directed, contains 40 mg of famotidine, USP, along with inactive ingredients including citric acid monohydrate, flavors (cherry, banana, and peppermint), powdered cellulose, sucrose, and xanthan gum. Preservatives included are sodium benzoate (0.1%), methylparaben sodium (0.1%), and propylparaben sodium (0.02%).

Famotidine, USP appears as a white to pale yellowish white crystalline compound. It is freely soluble in dimethyl formamide and glacial acetic acid, slightly soluble in methanol, very slightly soluble in water, and practically insoluble in acetone, alcohol, chloroform, ether, and ethyl acetate.

Uses and Indications

Famotidine for oral suspension is indicated for the treatment of several gastrointestinal conditions in both adults and pediatric patients.

In adults, this medication is indicated for the management of active duodenal ulcers (DU) and active gastric ulcers (GU). It is also indicated for the relief of symptoms associated with nonerosive gastroesophageal reflux disease (GERD) and for the treatment of erosive esophagitis due to GERD, as confirmed by biopsy. Additionally, famotidine is indicated for the treatment of pathological hypersecretory conditions, including Zollinger-Ellison syndrome and multiple endocrine neoplasias, and for the reduction of the risk of DU recurrence.

In pediatric patients aged 1 year and older, famotidine is indicated for the treatment of peptic ulcers and GERD, with or without esophagitis and ulcerations. For pediatric patients from birth to less than 1 year of age, the drug is indicated for the treatment of GERD.

There are no teratogenic or nonteratogenic effects associated with famotidine as per the available data.

Dosage and Administration

The recommended adult dosage varies by indication. For active duodenal ulcers (DU), the dosage is 40 mg once daily or 20 mg twice daily. In cases of active gastric ulcers (GU), the dosage is 40 mg once daily. For symptomatic nonerosive gastroesophageal reflux disease (GERD), the recommended dosage is 20 mg twice daily. In the treatment of erosive esophagitis due to GERD, the dosage may be 20 mg twice daily or 40 mg twice daily. 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 DU recurrence, a dosage of 20 mg once daily is recommended.

For pediatric patients, the recommended dosage for peptic ulcer disease in children aged 1 year to less than 17 years is a starting dosage of 0.5 mg/kg once daily or 0.25 mg/kg twice daily, with the possibility of increasing to 1 mg/kg once daily at bedtime or 0.5 mg/kg twice daily, not exceeding a maximum of 40 mg per day. For GERD in infants from birth to less than 3 months, the starting dosage is 0.5 mg/kg once daily, which may be increased to 1 mg/kg once daily. In children aged 3 months to less than 1 year, the starting dosage is 0.5 mg/kg twice daily, with a potential increase to 1 mg/kg twice daily, also not exceeding 40 mg per day. For GERD with or without esophagitis and ulcerations in children aged 1 year to less than 17 years, the recommended dosage is 0.5 mg/kg twice daily, with a maximum of 40 mg twice daily.

Administration should occur once daily before bedtime or twice daily in the morning and before bedtime, with or without food.

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 when using this medication; therefore, it is essential to consider dosage reduction in these populations to mitigate potential adverse effects.

It is important to note that the absence of gastrointestinal symptoms does not rule out the possibility of gastric malignancy. A thorough evaluation should be conducted prior to initiating therapy to ensure patient safety and appropriate treatment planning.

No additional general precautions or laboratory tests have been specified; however, healthcare professionals should remain vigilant and monitor patients closely for any signs of complications or adverse reactions throughout the course of treatment.

Side Effects

Patients may experience a range of adverse reactions while undergoing treatment. Common adverse reactions reported include headache, dizziness, constipation, and diarrhea.

Particular attention should be given to central nervous system (CNS) adverse reactions, especially in elderly patients and those with renal impairment, as these populations are at an increased risk. It is recommended to reduce the dosage in these cases to mitigate potential risks.

It is important to note that the absence of gastrointestinal (GI) symptoms does not rule out the possibility of gastric malignancy; therefore, a thorough evaluation should be conducted prior to initiating therapy.

Additionally, patients with a history of serious hypersensitivity reactions, such as anaphylaxis, to famotidine or other H2 receptor antagonists should be closely monitored.

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 guidelines.

Drug Interactions

Concomitant use of drugs that depend on gastric pH for absorption may lead to a significant reduction in systemic exposure of the affected drug, potentially resulting in a loss of efficacy. It is advisable to consult the full prescribing information for a comprehensive list of these interacting drugs.

When considering the use of tizanidine, which is a substrate of CYP1A2, there is a potential for substantial increases in blood concentrations. This elevation may result in adverse effects such as hypotension, bradycardia, or excessive drowsiness. Therefore, it is recommended to avoid concomitant use of tizanidine if possible to mitigate these risks.

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 for oral suspension have been established in pediatric patients aged 1 year to less than 17 years for the treatment of peptic ulcer disease and gastroesophageal reflux disease (GERD), with or without esophagitis and ulcerations. In pediatric patients from birth to less than 1 year of age, famotidine has been shown to be safe and effective for the treatment of GERD. However, the safety and effectiveness of famotidine for the treatment of peptic ulcer disease in this younger age group have not been established.

Additionally, the safety and effectiveness of famotidine for the treatment of pathological hypersecretory conditions and for the reduction of the risk of duodenal ulcer recurrence have not been established in pediatric patients. It is important to note that a safe and effective dosage has not been determined for pediatric patients with renal impairment.

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 post-marketing experience has indicated that central nervous system (CNS) adverse reactions have been reported in this population, regardless of renal function status.

Famotidine is primarily excreted by the kidneys, which raises the potential risk of adverse reactions in elderly patients, especially those with compromised renal function. Therefore, it is advisable to use the lowest effective dose of famotidine for oral suspension in geriatric patients and to closely monitor their renal function throughout the treatment period. This approach will help mitigate the risk of adverse effects and ensure the safe use of famotidine in this vulnerable 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 2,000 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.

There are, however, 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 limited data available on the presence of famotidine in human breast milk. Current evidence indicates that there were no effects observed on breastfed infants. However, there are no data regarding the effects of famotidine on milk production in lactating mothers.

In animal studies, famotidine has been detected in the milk of lactating rats. Notably, transient growth depression was observed in young rats suckling from mothers treated with maternotoxic doses of famotidine that were at least 600 times the usual human dose.

When considering the use of famotidine in lactating mothers, the developmental and health benefits of breastfeeding should be weighed against the mother's clinical need for famotidine and any potential adverse effects on the breastfed child from either the medication or the underlying maternal condition.

Renal Impairment

Patients with moderate and severe renal impairment may experience CNS adverse reactions and prolonged QT intervals. The clearance of famotidine is significantly reduced in these patients compared to those with normal renal function. For adults with mild renal impairment, defined as a creatinine clearance of greater than or equal to 60 mL/minute, no dosage adjustment is necessary. However, a dosage reduction is recommended for adults with moderate or severe renal impairment, where creatinine clearance is less than 60 mL/minute.

It is important to note that data are not available to establish a safe and effective dosage in pediatric patients with renal impairment. Additionally, elderly patients and those with renal impairment are at an increased risk for CNS adverse reactions; therefore, dosage reduction should be considered in these populations.

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 consistent with those associated with the administration of recommended dosages. Healthcare professionals should be vigilant for these reactions, which may include a range of symptoms similar to those seen at therapeutic levels.

Management of overdosage should be primarily symptomatic and supportive. It is essential to remove any unabsorbed material from the gastrointestinal tract promptly. This may involve the use of activated charcoal or other appropriate measures, depending on the clinical scenario. Continuous monitoring of the patient is crucial to assess for any evolving symptoms and to provide necessary supportive therapy.

Due to famotidine's low binding affinity to plasma proteins, it is primarily eliminated through hemodialysis. However, it is important to note that there is limited clinical experience regarding the efficacy of hemodialysis in the treatment of famotidine overdosage. Therefore, while hemodialysis may be considered in severe cases, its role should be evaluated on a case-by-case basis, taking into account the patient's overall clinical condition and response to initial management strategies.

Nonclinical Toxicology

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 2,000 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.

Famotidine demonstrated a negative result 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, showed no evidence of mutagenic effects.

In studies involving rats administered oral doses of up to 2,000 mg/kg/day (approximately 243 times the recommended human dose of 80 mg per day), fertility and reproductive performance were not adversely affected.

Postmarketing Experience

No specific postmarketing experience details are available. As such, there are no additional adverse events or rare case reports to summarize at this time.

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 and their caregivers should be instructed on the proper administration of Famotidine, which may be taken once daily before bedtime or twice daily, in the morning and before bedtime, as recommended. It is also essential to inform them that Famotidine can be taken with or without food, and that it may be administered alongside antacids if needed.

Storage and Handling

Famotidine for oral suspension, USP is supplied as a dry powder that must be constituted prior to use. It should be stored at a temperature range of 20° to 25°C (68° to 77°F), with permissible excursions between 15° to 30°C (59° to 86°F). It is essential to protect the product from freezing to maintain its efficacy.

Once constituted, the suspension must be discarded after 30 days if not used. For dispensing, it is required to use a USP tight, light-resistant container to ensure the integrity of the product during storage and handling.

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 Amneal Pharmaceuticals NY LLC. It includes detailed information about indications, dosage, contraindications, warnings, and clinical pharmacology.

View full prescribing information (PDF)