Entecavir Oral Solution

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

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1 DEFINITION

Entecavir Oral Solution contains NLT 90.0% and NMT 105.0% of the labeled amount of entecavir (C₁₂H₁₅N₅O₃).

2 IDENTIFICATION

A. The retention time of the major peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.

B. The UV spectrum of the major peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.

3 ASSAY

PROCEDURE

Solution A: 19.1 g/L of sodium tetraborate, decahydrate in water. Add 35 ml of methanol per liter of the solution. Pass through a suitable filter of 0.45-μm pore size.

Solution B: Methanol

Mobile phase: See Table 1

Diluent: Methanol and water (20:80)

System suitability solution: 0.05 mg/mL of USP Entecavir Monohydrate RS and 1.5 mg/ml of methylparaben prepared as follows. Transfer an amount of USP Entecavir Monohydrate RS and methylparaben to a suitable volumetric flask and add about 5% of the flask volume of methanol. Sonicate to dissolve. Dilute with Diluent to volume.

Standard stock solution: 0.2 mg/mL of USP Entecavir Monohydrate RS prepared as follows. Transfer an amount of USP Entecavir Monohydrate RS to a suitable volumetric flask and add about 4% of the flask volume of methanol. Sonicate to dissolve. Dilute with Diluent to volume.

Standard solution: 0.05 mg/ml, of USP Entecavir Monohydrate RS in Diluent from Standard stock solution

Sample solution: Nominally 0.05 mg/ml, of entecavir from a measured volume of Oral Solution

Chromatographic system

(See Chromatography (623). Svstem Suitability.)

Mode: LC

Detector: UV 254 nm. For Ideritification B, use a diode array detector in the range of 200-400 nm.

Column: 4.6 mm x 15-cm; 3.5 µm packing 11

Column temperature: 30°

Flow rate: 0.8 mL/min

Injection volume: 20 µl

System suitability

Samples: System suitability solution and Standard solution

[NOTE-The relative retention times for entecavir and methylparaben are 1.0 and 1.2, respectively)

Suitability requirements

Resolution: NLT 2.0 between entecavir and methylparaben, System suitability solution

Tailing factor: NMT 2.0, Standard solution

Relative standard deviation: NMT 2.0%, Standard solution

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of entecavir (C₁₂H₁₅N₅O₃) in the portion of Oral Solution taken:

Result = (r_U/(r_S) × (C_S /C_U) x 100

r_U = peak response of entecavir from the Sample solution

r_S = peak response of entecavir from the Standard solution

C_S = concentration of USP Entecavir Monohydrate RS in the Standard solution (mg/ml)

C_U = concentration of Entecavir in the Sample solution (mg/mL)

Acceptance criteria: 90.0%-105.0%

4 PERFORMANCE TESTS

DELIVERABLE VOLUME (698)

For multiple-unit containers: Meets the requirements.

5 IMPURITIES

ORGANIC IMPURITIES

Solution A, Solution B, Mobile phase, Diluent, System suitability solution, Standard stock solution, Standard solution, Sample solution,

Analysis

Sample: Sample solution

Result = (r_U/(r_S) x 100

Acceptance criteria: See Table 2

^a 2-(19-(15,3R,45)-4-Hydroxy-3-(hydroxymethyl)-2-methylenecyclopentyl)-6-oxo-6,9-dihydro-1h-purin-2-yl)amino)propanoic acid. Configuration of epimers may be interchangeable.

6 SPECIFIC TESTS

MICROBIAL ENUMERATIKIN TESTS (61) and TESTS FOR SPECIFICS MICROORGANISMS (62): The total aerobic microbial count does not exceed 10 cfu/mL

The total yeasts and molds count is NMT 10 cfu/mL. It meets the requirements of the test for absence of Escherichia coli.

7 ADDITIONAL REQUIREMENTS

PACKAGING AND STORAGE: Preserve in tight, light-resistant containers. Store at controlled room temperature.