Famotidine (Page 3 of 6)

8.4 Pediatric Use

The safety and effectiveness of famotidine tablets 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 tablets and the recommended dosage of famotidine tablets in these pediatric patients is supported by evidence from adequate and well-controlled studies of famotidine tablets in adults and published pharmacokinetic and pharmacodynamic data in pediatric patients [s ee 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).

8.5 Geriatric Use

Of the 1442 famotidine tablets-treated patients in clinical studies, approximately 10% were 65 and older. In these studies, no overall differences in safety or effectiveness were observed between elderly and younger patients. In postmarketing experience, CNS adverse reactions have been reported in elderly patients with and without renal impairment receiving famotidine tablets [ see Warnings and Precautions ( 5.1)] .

Famotidine is known to be substantially excreted by the kidney, and the risk of adverse reactions to famotidine tablets may be greater in elderly patients, particularly those with impaired renal function [ see Use in Specific Populations ( 8.6)] .

In general, use the lowest effective dose of famotidine tablets for an elderly patient and monitor renal function [see Dosage and Administration ( 2.2)].

8.6 Renal Impairment

CNS adverse reactions and prolonged QT intervals have been reported in patients with moderate and severe renal impairment [see Warnings and Precautions ( 5.1)]. The clearance of famotidine is reduced in adults with moderate and severe renal impairment compared to adults with normal renal function [see Clinical Pharmacology ( 12.3)]. No dosage adjustment is needed in patients with mild renal impairment (creatinine clearance greater than or equal to 60 mL/minute). Dosage reduction is recommended in adult and pediatric patients greater than or equal to 40 kg with moderate or severe renal impairment (creatinine clearance less than 60 mL/minute) [see Dosage and Administration ( 2.2)].

10 OVERDOSAGE

The types of adverse reactions in overdosage of famotidine tablets 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 tablets overdosage.

11 DESCRIPTION

The active ingredient in Famotidine Tablets USP is a histamine-2 (H 2 ) receptor antagonist. Famotidine, USP is [1-Amino-3-[[[2-[(diaminomethylene)amino]-4-thiazolyl]methyl]thio] propylidene] sulfamide and has the following structural formula:

Structural Formula
(click image for full-size original)

C 8 H 15 N 7 O 2 S 3 M.W. 337.45


Each Famotidine Tablet USP for oral administration contains either 20 mg or 40 mg of famotidine, USP and has the following inactive ingredients: colloidal silicon dioxide, hypromellose, magnesium stearate, microcrystalline cellulose, polyethylene glycol, pregelatinized corn starch, sodium starch glycolate, talc, titanium dioxide, yellow iron oxide. In addition the 20 mg contains lactose monohydrate, red iron oxide and triacetin and the 40 mg contains FD&C blue No. 2 aluminum lake and FD&C yellow No. 6 aluminum lake.

Famotidine, USP is a white to pale yellow crystalline compound that is freely soluble in glacial acetic acid, slightly soluble in methanol, very slightly soluble in water, and practically insoluble in ethanol.

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 tablets, the onset of the antisecretory effect occurred within one hour; the maximum effect was dose-dependent, occurring within one to three hours. Duration of inhibition of secretion by doses of 20 mg and 40 mg was 10 to 12 hours.

Single evening oral doses of 20 mg and 40 mg inhibited basal and nocturnal acid secretion in all subjects; mean nocturnal gastric acid secretion was inhibited by 86% and 94%, respectively, for a period of at least 10 hours. The same doses given in the morning suppressed food-stimulated acid secretion in all subjects. The mean suppression was 76% and 84%, respectively, 3 to 5 hours after administration, and 25% and 30%, respectively, 8 to 10 hours after administration. In some subjects who received the 20 mg dose, however, the antisecretory effect was dissipated within 6 to 8 hours. There was no cumulative effect with repeated doses. The nocturnal intragastric pH was raised by evening doses of 20 mg and 40 mg of famotidine tablets to mean values of 5.0 and 6.4, respectively. When famotidine tablets was given after breakfast, the basal daytime interdigestive pH at 3 and 8 hours after 20 mg or 40 mg of famotidine was raised to about 5.

Famotidine had little or no effect on fasting or postprandial serum gastrin levels. Gastric emptying and exocrine pancreatic function were not affected by famotidine tablets.

In clinical pharmacology studies, systemic effects of famotidine in the CNS, cardiovascular, respiratory or endocrine systems were not noted. Also, no anti-androgenic effects were noted. Serum hormone levels, including prolactin, cortisol, thyroxine (T4), and testosterone, were not altered after treatment with famotidine.

Pediatric Patients

Pharmacodynamics of famotidine, assessed by gastric pH, were evaluated in 5 pediatric patients 2 to 13 years of age using the sigmoid Emax model. These data suggest that the relationship between serum concentration of famotidine and gastric acid suppression is similar to that observed in adults (see Table 3).

Table 3: Serum Concentrations of Famotidine Associated with Gastric Acid Reduction in Famotidine Tablets-Treated Pediatric and Adult Patients a

EC 50 (ng/mL) a

Pediatric Patients

26 ± 13

Adults

Healthy adult subjects

26.5 ± 10.3

Adult patients with upper GI bleeding

18.7 ± 10.8

a Using the Sigmoid Emax model, serum concentrations of famotidine associated with 50% maximum gastric acid reduction are presented as means ± SD.

In a study examining the effect of famotidine on gastric pH and duration of acid suppression in pediatric patients, four pediatric patients ages 11 to 15 years of age using the oral formulation at a dose of 0.5 mg/kg, maintained a gastric pH above 5 for 13.5 ± 1.8 hours.

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