Phenoxybenzamine Hydrochloride 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

Phenoxybenzamine Hydrochloride Compounded Oral Suspension contains NLT 90.0% and NMT 110.0% of the labeled amount of phenoxybenzamine hydrochloride (C₁₈H₂₂CINO·HCI).

Prepare Phenoxybenzamine Hydrochloride Compounded Oral Suspension 10 mg/mL as follows (see Pharmaceutical Compounding-Nonsterile Preparations (795)).

Pour the weighed Phenoxybenzamine Hydrochloride powder into a suitable mortar. Wet the powder with a small amount of Corn Oil, and triturate to make a smooth paste. Add the Corn Oil to make the mortar contents pourable. Transfer the contents of the mortar, stepwise and quantitatively, to a calibrated container using the Corn Oil to rinse the mortar. Add sufficient Corn Oil to bring the preparation to final volume. Shake to mix well.

2 ASSAY

2.1 PROCEDURE

Solution A: 25 mM monobasic potassium phosphate adjusted with phosphoric acid to a pH of 3.1

Mobile phase: Acetonitrile and Solution A (70:30)

Diluent: Prepare a mixture of 20 mL of acetonitrile and 80 mL of isopropyl alcohol in a conical flask. Add 10 g of anhydrous sodium sulfate to the flask, shake well for 1 min, and allow the sodium sulfate to precipitate to the bottom. [NOTE-The addition of anhydrous sodium sulfate removes trace amounts of water in the solvent.]

Standard solution: 0.5 mg/mL of phenoxybenzamine hydrochloride prepared from USP Phenoxybenzamine Hydrochloride RS in acetonitrile

Sample solution: Shake thoroughly each bottle of Oral Suspension. Transfer 0.5 mL of the Oral Suspension into a 10-mL volumetric flask, dilute with Diluent to volume, and mix well to dissolve.

2.2 Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 220 nm

Column: 3.9-mm x 15-cm; 5-µm packing L1

Flow rate: 1.5 mL/min

Injection volume: 10 µL

2.3 System suitability

Sample: Standard solution

[NOTE-The retention time for phenoxybenzamine hydrochloride is about 5.2 min.]

Suitability requirements

Tailing factor: NMT 2.0

Relative standard deviation: NMT 2.0% for replicate injections

2.4 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of phenoxybenzamine hydrochloride (C₁₈H₂₂CINO·HCI) in the portion of Oral Suspension taken:

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

r_U = peak response of phenoxybenzamine hydrochloride from the Sample solution

r_S = peak response of phenoxybenzamine hydrochloride from the Standard solution

C_S = concentration of phenoxybenzamine hydrochloride in the Standard solution (mg/mL)

C_U = nominal concentration of phenoxybenzamine hydrochloride in the Sample solution (mg/mL)

Acceptance criteria: 90.0%-110.0%

3 ADDITIONAL REQUIREMENTS

3.1 PACKAGING AND STORAGE

Package in tight, light-resistant containers. Store at 2°-8° or at controlled room temperature.

3.2 BEYOND-USE DATE

NMT 90 days after the date on which it was compounded when stored at 2°-8° or controlled room temperature

3.3 LABELING

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

3.4 USP REFERENCE STANDARDS (11)

USP Phenoxybenzamine Hydrochloride RS