Amlodipine 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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1 DEFINITION

Amlodipine Compounded Oral Suspension contains NLT 90.0% and NMT 110.0% of the labeled amount of amlodipine (C₂₀H₂₅ClN₂O₅).

Prepare Amlodipine Compounded Oral Suspension 1 mg/mL as follows (see Pharmaceutical Compounding-Nonsterile Preparations 〈795〉).

^a Norvasc 5-mg tablets, Pfizer, Inc., Groton, CT.

^b Paddock Laboratories, Minneapolis, MN.

Calculate the required quantity of each ingredient for the total amount to be prepared. Place the required number of 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 amlodipine 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. [Note-To ensure component uniformity, homogenization is recommended.]

2 ASSAY

2.1 Procedure

Mobile phase: Acetonitrile, methanol, and 40 mM ammonium acetate (50:15:35). Filter through a nylon 66 filter of 0.45-μm pore size, and degas.

Standard stock solution: Dissolve an appropriately weighed amount of USP Amlodipine Besylate RS in methanol, equivalent to 1.0 mg/mL of amlodipine (approximately equal to 1.4 mg/mL of amlodipine besylate).

Standard solution: Transfer 1.0 mL of the Standard stock solution into a 50-mL volumetric flask, and dilute with Mobile phase to volume to obtain a solution with a nominal concentration of about 20 μg/mL of amlodipine. Centrifuge.

Sample solution: Shake thoroughly by hand each bottle of Oral Suspension. Pipet 1.0 mL of Oral Suspension into a 50-mL volumetric flask, rinse the pipet three times with Mobile phase, and dilute with Mobile phase to volume to obtain a solution with a nominal concentration of about 20 μg/mL of amlodipine. Centrifuge.

2.2 Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 240 nm

Column: 3.0-mm × 15-cm; 5-μm packing L10

Flow rate: 0.4 mL/min

Injection volume: 10 μL

2.3 System suitability

Sample: Standard solution

[Note-The retention time for amlodipine is about 10.1 min.]

2.4 Suitability requirements

Column efficiency: NLT 4000 theoretical plates

Tailing factor: NMT 2.0

Relative standard deviation: NMT 2.0% for replicate injections

2.5 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of amlodipine (C₂₀H₂₅ClN₂O₅) in the portion of Oral Suspension taken:

Result = (r_U/r_S) × (C_S/C_U) × 100

r_U = peak response of amlodipine from the Sample solution

r_S = peak response of amlodipine from the Standard solution

C_S = concentration of amlodipine in the Standard solution (μg/mL)

C_U = nominal concentration of amlodipine in the Sample solution (μg/mL)

Acceptance criteria: 90.0%–110.0%

3 SPECIFIC TESTS

pH 〈791〉: 4.0–5.0

4 ADDITIONAL REQUIREMENTS

Packaging and Storage: Package in tight, light-resistant containers. Store in a refrigerator or at controlled room temperature.

Beyond-Use Date: NMT 90 days after the date on which it was compounded when stored in a refrigerator; NMT 60 days when stored 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.

USP Reference Standards 〈11〉

USP Amlodipine Besylate RS