Prazosin 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)

DOWNLOAD PDF HERE

1 DEFINITION

Prazosin Hydrochloride Compounded Oral Suspension contains NLT 90.0% and NMT 110.0% of the labeled amount of prazosin (C₁₉H₂₁N₅O₄ ). 

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

Empty the required number of Prazosin Hydrochloride capsules into a suitable container. Add a small amount of Ora-Blend and mix well to form a smooth paste. Add a sufficient amount of Ora-Blend to make the contents pourable. Transfer the contents stepwise and quantitatively to a calibrated container using the remainder of the Ora-Blend. Add succulent Ora-Blend to bring to nal volume. Shake well.

2 ASSAY

Change to read:

Procedure

Mobile phase: Add 1.74 g of sodium 1-pentanesulfonate and 3.64 mL of a 25% tetramethylammonium hydroxide (ERR 1-Mar-2019) solution to 500 mL of water. Adjust with glacial acetic acid to a pH of 5.0. Add 500 mL of methanol.

Standard solution: Transfer 21.90 mg of USP Prazosin Hydrochloride RS (equivalent to 20 mg of prazosin) to a 200-mL volumetric flask and dissolve in 20 mL of methanol. Add Mobile phase to volume.

Sample solution: Transfer 1.0 mL of Oral Suspension into a 10-mL volumetric flask. Dissolve in about 8 mL of methanol. Add Mobile phase to volume. Pass through a filter of 0.22-µm pore size.

2.1 Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 250 nm

Column: 4.6-mm × 25-cm; 5-µm packing L1

Column temperature: 15°

Flow rate: 1.0 mL/min

Injection volume: 10 µL

2.2 System suitability

Sample: Standard solution

[Note—The retention time for prazosin is about 10.0 min.]

Suitability requirements

Tailing factor: NMT 2.0

Relative standard deviation: NMT 2.0% for replicate injections

2.3 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of prazosin (C₁₉H₂₁N₅O₄) in the portion of Oral Suspension taken:

Result = (r_U /r_S ) × (C_S /C_U ) × (M_r1 /M_r2) × 100

r_U = peak response of prazosin from the Sample solution

r_S = peak response of prazosin from the Standard solution

C_S = concentration of USP Prazosin Hydrochloride RS in the Standard solution (mg/mL)

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

M_r1 = molecular weight of prazosin, 383.40

M_r2 = molecular weight of prazosin hydrochloride, 419.86

Acceptance criteria: 90.0%–110.0%

3 SPECIFIC TESTS

pH 〈791〉: 4.6–5.6

4 ADDITIONAL REQUIREMENTS

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

Beyond-Use Date: NMT 90 days after the date on which it was compounded when stored at controlled room temperature or in a refrigerator

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 Prazosin Hydrochloride RS2S (USP41)