Famotidine

Description

Famotidine for Oral Suspension, USP contains famotidine as the active ingredient, which is classified as an H2-receptor antagonist. The chemical structure of famotidine is represented by the name N'-(aminosulfonyl)-3-[[[2-(diaminomethylene)amino-4-thiazolyl]methyl]thio]propanimidamide. Its empirical formula is C8H15N7O2S3, and it has a molecular weight of 337.43 g/mol.

The compound appears as a white to pale yellow crystalline substance. It is freely soluble in glacial acetic acid, slightly soluble in methanol, very slightly soluble in water, and practically insoluble in ethanol. Each 5 mL of the prepared oral suspension contains 40 mg of famotidine along with inactive ingredients, which include edetate disodium dihydrate, microcrystalline cellulose, sucrose, xanthan gum, and flavors (banana and peppermint). Preservatives included in the formulation are sodium benzoate, methylparaben sodium, and propylparaben sodium.

Uses and Indications

Famotidine for Oral Suspension is indicated for the treatment of various gastrointestinal conditions. In adults, it is indicated for the management of active duodenal ulcers (DU), active gastric ulcers (GU), symptomatic nonerosive gastroesophageal reflux disease (GERD), erosive esophagitis due to GERD as diagnosed by biopsy, and pathological hypersecretory conditions such as Zollinger-Ellison syndrome and multiple endocrine neoplasias. Additionally, it is indicated for the reduction of the risk of DU recurrence.

In pediatric patients aged 1 year and older, Famotidine for Oral Suspension 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, it is indicated for the treatment of GERD.

There are no teratogenic or nonteratogenic effects associated with this medication.

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 recommended dosage is 40 mg once daily. For symptomatic nonerosive gastroesophageal reflux disease (GERD), the 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 dosage is determined by age and indication. For peptic ulcer disease in children aged 1 year to less than 17 years, the starting dosage is 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. For infants 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. In children aged 1 year to less than 17 years with GERD, with or without esophagitis and ulcerations, 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 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 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.

Additionally, 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.

Patients with a history of serious hypersensitivity reactions, such as anaphylaxis, to famotidine or other H2-receptor antagonists should be closely monitored, as they may be at heightened risk for similar reactions.

In cases of overdosage, the types of adverse reactions observed are consistent with those encountered during 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 monitor the therapeutic effects of such drugs closely when used in conjunction with agents that alter gastric pH.

Tizanidine, a substrate of CYP1A2, may experience substantial increases in blood concentrations when used with inhibitors of this enzyme. This interaction can lead to adverse effects such as hypotension, bradycardia, or excessive drowsiness. Therefore, it is recommended to avoid concomitant use of tizanidine with CYP1A2 inhibitors whenever possible. If co-administration is necessary, careful monitoring of tizanidine levels and patient response is warranted, and dosage adjustments may be required to mitigate the risk of these adverse effects.

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 for Oral Suspension is effective for the treatment of GERD; however, its safety and effectiveness for treating peptic ulcer disease in this 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

In clinical studies involving famotidine, approximately 10% of the 1,442 treated patients 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 for oral suspension in geriatric patients. Additionally, regular monitoring of renal function is advised to ensure patient safety and to mitigate potential risks associated with the medication.

Pregnancy

Available data regarding the use of H2-receptor antagonists, including famotidine, in pregnant patients 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/day for the treatment of erosive esophagitis.

The estimated background risk for major birth defects and miscarriage in the indicated population is unknown. It is important to note that 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/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 no specific statements regarding the use of this medication in lactating mothers or its effects on breastfed infants. Healthcare professionals should consider the absence of data 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 adjustments are made based on individual patient needs.

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 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 use of recommended dosages. Healthcare professionals should be vigilant for these reactions, which may include symptoms such as headache, dizziness, and gastrointestinal disturbances.

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 administration of activated charcoal if the patient presents shortly after ingestion. Continuous monitoring of the patient is crucial to assess for any evolving symptoms and to provide appropriate supportive therapy as needed.

Due to famotidine's low binding to plasma proteins, it is noteworthy that the drug is eliminated through hemodialysis. However, 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 remains to be clearly defined, and healthcare providers should weigh the potential benefits against the available evidence.

Nonclinical Toxicology

Carcinogenic potential of famotidine was assessed 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/day for the treatment of erosive esophagitis), there was no evidence of carcinogenic potential for famotidine.

Famotidine was negative in the microbial mutagen test (Ames test) using Salmonella typhimurium and Escherichia coli with or 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 a mutagenic effect.

In studies involving rats administered oral doses of up to 2000 mg/kg/day (approximately 243 times the recommended human dose of 80 mg/day), 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 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 medication. 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, dizziness, or lightheadedness, to their healthcare provider without delay.

Patients should be instructed on the proper administration of Famotidine for Oral Suspension. They should use an oral dosing syringe to accurately measure the prescribed amount of medication, which can be obtained from the pharmacy. Prior to each use, patients or caregivers should shake the bottle of reconstituted Famotidine for Oral Suspension vigorously for 5 to 10 seconds.

Patients should take the medication once daily before bedtime or twice daily, as recommended, in the morning and before bedtime. It can be taken with or without food and may be given alongside antacids if needed.

Storage and Handling

Famotidine for Oral Suspension is supplied as a dry powder that, once constituted, must be stored at a temperature of 25°C (77°F). Temperature excursions are permissible between 15° to 30°C (59° to 86°F). It is essential to protect the product from freezing to maintain its integrity.

The constituted suspension should be discarded after 30 days if not used. For optimal storage conditions, the product must be dispensed in a USP tight, light-resistant container to ensure its stability and efficacy.

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 Lannett Company, Inc.. It includes detailed information about indications, dosage, contraindications, warnings, and clinical pharmacology.

View full prescribing information (PDF)