Enalapril Maleate Compounded Oral Suspension

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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DEFINITION

Enalapril Maleate Compounded Oral Suspension contains NLT 90.0% and NMT 110.0% of the labeled content of enalapril maleate (C₂₀H₂₈N₂O₅ · C₄H₄O₄).

Prepare Enalapril Maleate Compounded Oral Suspension 1 mg/mL as follows (see Pharmaceutical Compounding Nonsterile Preparations (795)).

^aVasotec 20-mg tablets, Merck Sharp & Dohme, West Point, PA.

^bPaddock Laboratories, Minneapolis, MN,

Calculate the required quantity of each ingredient for the total amount to be prepared. Place the required number of Enalapril Maleate tablets in a suitable mortar, and comminute to a fine powder. Add the Vehicle in small portions, and triturate to make a smooth paste. Add increasing volumes of the Vehicle to make an enalapril maleate liquid that is pourable. Transfer the contents of the mortar, stepwise and quantitatively, to a calibrated bottle. Add enough of the Vehicle to bring to final volume, and mix well.

1 ASSAY

PROCEDURE

Buffer solution: 1 M monobasic potassium phosphate, adjusted with phosphoric acid to a pH of 4.0

Mobile phase: Acetonitrile, Buffer solution, and water (30:2:68). Filter and degas.

Standard solution: 0.1 mg/mL of USP Enalapril Maleate RS in Mobile phase

Sample solution: Shake thoroughly by hand each bottle of Oral Suspension. Pipet 1.0 ml of the Oral Suspension into a 10-ml. volumetric flask, and dilute with Mobile phase to volume to obtain a solution with a nominal concentration of 0.1 mg/ml of enalapril maleate.

Chromatographic system

(See Chromatography (621), System Suitability)

Mode: LC

Detector: UV 215 nm

Column: 4.6-mm × 25-cm; 5-μm packing L7

Flow rate: 1.5 mL/min

Injection volume: 20 µL

System suitability

Sample: Standard solution

Nore-The retention time for enalapril maleate is about 8.8 min.)

Suitability requirements

Relative standard deviation: NMT 2.1% for the replicate injections

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of enalapril maleate (C₂₀H₂₈N₂O₅ · C₄H₄O₄) in the portion of Oral Suspension taken:

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

r_U = peak response from the Sample solution

r_S = peak response from the Standard solution

C_S = concentration of USP Enalapril Maleate RS in the Standard solution (mg/ml)

C_U = nominal concentration of Enalapril Maleate in the Sample solution (mg/mL)

Acceptance criteria: 90.0% - 110.0%

2 SPECIFIC TESTS

PH (791): 4.2-5.3

3 ADDITIONAL REQUIREMENTS

PACKAGING AND STORAGE: Package in tight, light-resistant containers. Store at controlled room temperature or in a refrigerator.

BEYOND-USE DATE: NMT 60 days after the date on which it was compounded, when stored in a refrigerator or at controlled room temperature

LABELING: Label it to indicate that it is to be well shaken before use, and to state the Beyond-Use Date