Esomeprazole Magnesium (Page 6 of 13)

8.5 Geriatric Use

Of the total number of patients who received esomeprazole magnesium delayed-release capsules in clinical trials, 1,459 were 65 to 74 years of age and 354 patients were 75 years of age and older.

No overall differences in safety and efficacy were observed between the elderly and younger individuals, and other reported clinical experience has not identified differences in responses between the elderly and younger patients, but greater sensitivity of some older individuals cannot be ruled out.

8.6 Hepatic Impairment

In patients with severe hepatic impairment (Child-Pugh Class C) exposure to esomeprazole substantially increased compared to healthy subjects. Dosage modification of esomeprazole is recommended for patients with severe hepatic impairment for the healing of EE, risk reduction of NSAID-associated gastric ulcer, H. pylori eradication to reduce the risk of duodenal ulcer recurrence, and pathological hypersecretory conditions including Zollinger-Ellison Syndrome [see Dosage and Administration (2.1), Clinical Pharmacology (12.3)].

In patients with mild to moderate liver impairment (Child-Pugh Classes A and B), no dosage adjustment is necessary.

10 OVERDOSAGE

Manifestations in patients exposed to omeprazole, the racemic mixture, at doses up to 2,400 mg (120 times the usual recommended clinical dose) include confusion, drowsiness, blurred vision, tachycardia, nausea, diaphoresis, flushing, headache, dry mouth, and other adverse reactions similar to those seen at recommended dosages. See the full prescribing information for omeprazole for complete safety information. No specific antidote for esomeprazole is known. Since esomeprazole is extensively protein bound, it is not expected to be removed by dialysis. In the event of overdosage, treatment should be symptomatic and supportive.

If over-exposure occurs, call your Poison Control Center at 1-800-222-1222 for current information on the management of poisoning or overdosage.

11 DESCRIPTION

The active ingredient in the proton pump inhibitor esomeprazole magnesium delayed-release capsules for oral administration is bis(5-methoxy-2-[(S)-[(4-methoxy-3,5-dimethyl-2-pyridinyl)methyl]sulfinyl]-1H -benzimidazole-1-yl) magnesium trihydrate. Esomeprazole is the S-isomer of omeprazole, which is a mixture of the S- and R- isomers. (Initial U.S. approval of esomeprazole magnesium: 2001). Its molecular formula is (C17 H18 N3 O3 S)2 Mg x 3 H2 O with molecular weight of 767.17 as a trihydrate and 713.1 on an anhydrous basis. The structural formula is:

Figure 1

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(click image for full-size original)

The magnesium salt is a white or slightly colored powder. It contains 3 moles of water of solvation and is slightly soluble in methanol, insoluble in water and in n-Heptane. The stability of esomeprazole magnesium is a function of pH; it rapidly degrades in acidic media, but it has acceptable stability under alkaline conditions. At pH 6.8 (buffer), the half-life of the magnesium salt is about 19 hours at 25°C and about 8 hours at 37°C.

Esomeprazole magnesium delayed-release capsules are supplied in delayed-release capsules. Each delayed-release capsule contains 20 mg, or 40 mg of esomeprazole (present as 22.25 mg, or 44.50 mg esomeprazole magnesium trihydrate) in the form of enteric-coated granules with the following inactive ingredients: hydroxypropyl cellulose, hypromellose 2910, magnesium stearate, methacrylic acid and ethyl acrylate copolymer dispersion, mono-and di-glycerides, polysorbate 80, sugar spheres, talc and triethyl citrate. The capsule shells have the following inactive ingredients: gelatin, sodium lauryl sulfate and titanium dioxide. The imprinting ink also contains ferric oxide black, shellac, strong ammonium solution, potassium hydroxide and propylene glycol.

12 CLINICAL PHARMACOLOGY

12.1 Mechanism of Action

Esomeprazole belongs to a class of antisecretory compounds, the substituted benzimidazoles, that suppress gastric acid secretion by specific inhibition of the H+/K+ ATPase enzyme system at the secretory surface of the gastric parietal cell. Esomeprazole is protonated and converted in the acidic compartment of the parietal cell forming the active inhibitor, the achiral sulphenamide. Because this enzyme system is regarded as the acid (proton) pump within the gastric mucosa, esomeprazole has been characterized as a gastric acid-pump inhibitor, in that it blocks the final step of acid production. This effect is dose-related and leads to inhibition of both basal and stimulated acid secretion irrespective of the stimulus.

12.2 Pharmacodynamics

Antisecretory Activity

Adults

The effect of esomeprazole magnesium delayed-release capsules on intragastric pH was determined in adult patients with symptomatic GERD in two separate studies. In the first study of 36 patients, esomeprazole magnesium delayed-release capsules 40 mg and 20 mg capsules were administered once daily over 5 days as shown in Table 5:

Table 5: Effect of Esomeprazole on Intragastric pH on Day 5 (N=36) Following Once Daily Dosing of Esomeprazole magnesium Delayed-Release Capsules in Adult Patients with Symptomatic GERD

1. Gastric pH was measured over a 24-hour period

2. p< 0.01 Esomeprazole magnesium delayed-release capsules 40 mg vs. esomeprazole magnesium delayed-release capsules 20 mg

Parameter Esomeprazole magnesium delayed-release capsules
40 mg once daily 20 mg once daily
% Time Gastric pH >41 (Hours) 70%2 (16.8 h) 53% (12.7 h)
Coefficient of variation 26% 37%
Median 24 Hour pH 4.92 4.1
Coefficient of variation 16% 27%

In a second study, the effect on intragastric pH of esomeprazole magnesium delayed-release capsules 40 mg administered once daily over a five-day period was similar to the first study, (% time with pH > 4 was 68% or 16.3 hours).

Serum Gastrin Effects

The effect of esomeprazole magnesium delayed-release capsules on serum gastrin concentrations was evaluated in approximately 2,700 patients in clinical trials of oral esomeprazole for up to 8 weeks and in over 1,300 patients for up 12 months. The mean fasting gastrin level increased in a dose-related manner. This increase in serum gastrin concentrations reached a plateau within two to three months of therapy and returned to baseline levels within four weeks after discontinuation of therapy.

Increased gastrin causes enterochromaffin-like cell hyperplasia and increased serum Chromogranin A (CgA) levels. The increased CgA levels may cause false positive results in diagnostic investigations for neuroendocrine tumors [see Warnings and Precautions (5.10)]

Enterochromaffin-like (ECL) Cell Effects

Human gastric biopsy specimens have been obtained from more than 3,000 patients (both pediatrics and adults) treated with omeprazole in long-term clinical trials. The incidence of ECL cell hyperplasia in these studies increased with time; however, no case of ECL cell carcinoids, dysplasia, or neoplasia has been found in these patients [see Nonclinical Toxicology (13.1)].

In over 1,000 patients treated with oral esomeprazole (10 mg, 20 mg or 40 mg/day) up to 12 months, the prevalence of ECL cell hyperplasia increased with time and dose. No patient developed ECL cell carcinoids, dysplasia, or neoplasia in the gastric mucosa.

Endocrine Effects

Esomeprazole had no effect on thyroid function in adults when given esomeprazole magnesium delayed-release capsules 20 mg or 40 mg once daily for 4 weeks. Other effects of esomeprazole on the endocrine system were assessed in studies of omeprazole. Oral doses of omeprazole 30 mg or 40 mg once daily for 2 to 4 weeks had no effect on carbohydrate metabolism, circulating levels of parathyroid hormone, cortisol, estradiol, testosterone, prolactin, cholecystokinin, or secretin.

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