Orally administered famotidine was compared to placebo in a U.S. study that enrolled patients with symptoms of GERD and without endoscopic evidence of erosion or ulceration of the esophagus. Famotidine 20 mg b.i.d. was statistically significantly superior to 40 mg h.s. and to placebo in providing a successful symptomatic outcome, defined as moderate or excellent improvement of symptoms (Table 3).
|Famotidine 20 mg b.i.d.(N=154)||Famotidine 40 mg h.s. (N=149)||Placebo (N=73)|
By two weeks of treatment symptomatic success was observed in a greater percentage of patients taking famotidine 20 mg b.i.d. compared to placebo (p <0.01).
Symptomatic improvement and healing of endoscopically verified erosion and ulceration were studied in two additional trials. Healing was defined as complete resolution of all erosions or ulcerations visible with endoscopy. The U.S. study comparing famotidine 40 mg p.o. b.i.d. to placebo and famotidine 20 mg p.o. b.i.d. showed a significantly greater percentage of healing for famotidine 40 mg b.i.d. at weeks 6 and 12 (Table 4).
|Famotidine 40 mg b.i.d. (N=127)||Famotidine 20 mg b.i.d. (N=125)|| |
As compared to placebo, patients who received famotidine had faster relief of daytime and nighttime heartburn and a greater percentage of patients experienced complete relief of nighttime heartburn. These differences were statistically significant.
In the international study, when famotidine 40 mg p.o. b.i.d., was compared to ranitidine 150 mg p.o. b.i.d., a statistically significantly greater percentage of healing was observed with famotidine 40 mg b.i.d. at week 12 (Table 5). There was, however, no significant difference among treatments in symptom relief.
|Famotidine 40 mg b.i.d. (N=175)||Famotidine 20 mg b.i.d. (N=93)||Ranitidine 150 mg b.i.d. (N=172)|
Pathological Hypersecretory Conditions (e.g., Zollinger-Ellison Syndrome, Multiple Endocrine Adenomas)
In studies of patients with pathological hypersecretory conditions such as Zollinger-Ellison Syndrome with or without multiple endocrine adenomas, famotidine significantly inhibited gastric acid secretion and controlled associated symptoms. Orally administered doses from 20 to 160 mg q 6 h maintained basal acid secretion below 10 mEq/hr; initial doses were titrated to the individual patient need and subsequent adjustments were necessary with time in some patients. Famotidine was well tolerated at these high dose levels for prolonged periods (greater than 12 months) in eight patients, and there were no cases reported of gynecomastia, increased prolactin levels, or impotence which were considered to be due to the drug.
Bioavailability studies of 8 pediatric patients (11-15 years of age) showed a mean oral bioavailability of 0.5 compared to adult values of 0.42 to 0.49. Oral doses of 0.5 mg/kg achieved an AUC of 580 + 60 ng-hr/mL in pediatric patients 11-15 years of age compared to 482 ± 181 ng-hr/mL in adults treated with 40 mg orally.
Pharmacodynamics of famotidine were evaluated in 5 pediatric patients 2 — 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 one study of adults (Table 6).
|Pediatric Patients||26 ± 13|
|Data from one study|
|a) healthy adult subjects||26.5 ± 10.3|
|b) adult patients with upper GI bleeding||18.7 ± 10.8|
In 4 pediatric patients 11 – 15 years of age given oral famotidine 0.5 mg/kg twice daily, gastric pH was greater than 5 for 5.0 + 1.1 hours.
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