Esomeprazole Identification and Assay by HPLC

Esomeprazole Magnesium and Esomeprazole Magnesium Delayed-Release Capsules USP Monograph Methods

Overview

Esomeprazole is the S-enantiomer of omeprazole.

Esomeprazole is a proton pump inhibitor and reduces acid secretion through inhibition of the H+/K+ ATPase in gastric parietal cells. By inhibiting the functioning of this transporter, the drug prevents formation of gastric acid. It is used in the treatment of dyspepsia, peptic ulcer disease, gastroesophageal reflux disease, and Zollinger-Ellison syndrome.

Common commercial brand names: Nexium, Essocam, and Esomezol

Esomeprazole magnesium was developed by AstraZeneca. In 2010, sales were $4.9 billion globally; the patent expired in 2014.

Esomeprazole

We have followed the USP 40–NF 35 experimental conditions for esomeprazole magnesium and esomeprazole magnesium delayed-release capsules and applied the following tests:

  • Identification—FTIR and AAS (content of magnesium)
  • Assay and Related Substances—HPLC and UHPLC (both isocratic and gradient methods)
  • Water Content—Karl Fischer Titration
  • Dissolution—HPLC

Identification and Assay

DEFINITION
Esomeprazole magnesium contains not less than (NLT) 98.0% and not more than (NMT) 102.0% of C34H36MgN6O6S2, calculated on the anhydrous basis.


IDENTIFICATION—FTIR <197K> and AAS

A. Infrared absorption

B. The sample solution, prepared and tested as directed in the test for Content of Magnesium, exhibits a significant absorption at 285.2 nm.

 

ASSAY—HPLC (gradient method)

Procedure:

Solution A: Dissolve 0.725 g of monobasic sodium phosphate and 4.472 g of anhydrous dibasic sodium phosphate in 300 mL of water, and dilute with water to 1,000 mL. Dilute 250 mL of this solution with water to 1,000 mL. If necessary, adjust with phosphoric acid to a pH of 7.6.

Solution B: Mix 11 mL of 0.25 M tribasic sodium phosphate with 22 mL of 0.5 M dibasic sodium phosphate, and dilute with water to 100 mL.

Mobile phase: Acetonitrile and Solution A (7:13)

Standard solution: Transfer 10 mg of USP Omeprazole to a 200-mL volumetric flask, and dissolve in approximately 10 mL of methanol. Add 10 mL of Solution B, and dilute with water to volume.
Note: This solution contains 0.05 mg/mL of omeprazole.

Sample solution: Transfer 10 mg of esomeprazole magnesium to a 200-mL volumetric flask, and dissolve in approximately 10 mL of methanol. Add 10 mL of Solution B, and dilute with water to volume. Note: This solution contains 0.05 mg/mL of esomeprazole magnesium.

 

Chromatographic System (See USP General Chapter 621, Chromatography, System Suitability.)

Detector: UV 280 nm
Column: 4.0 mm × 12.5 cm or a 4.6 mm × 15 cm (5 µm) packing L7. Note: Alternatively, a 3.9 mm × 15 cm column (4 µm) packing L1 may be used. Flow rate: 1 mL/min
Injection size: 20 µL

We have used a Purospher® STAR RP-8 endcapped (5 µm) 150 x 4.6 mm (Catalogue Number 1.51453) for HPLC analysis.

Materials

     
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