Acetazolamide 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

Acetazolamide Compounded Oral Suspension contains NLT 90.0% and NMT 110.0% of the labeled amount of acetazolamide (C₄H₆N₄O₃S₂). Prepare Acetazolamide Compounded Oral Suspension, 25 mg/mL, as follows (see Pharmaceutical Compounding-Nonsterile Preparations (795)).

If using tablets, place in a mortar and comminute to a fine powder, or add Acetazolamide powder. Add about 20 mL of the Vehicle, and mix to a uniform paste. Add the Vehicle in small portions almost to volume, and mix thoroughly after each addition. Transfer the contents of the mortar, stepwise and quantitatively, to a calibrated bottle. Add enough liquid Vehicle to bring to final volume, and mix well.

2 ASSAY

2.1 PROCEDURE

Mobile phase: Dissolve 4.1 g of anhydrous sodium acetate in 950 mL of water, and add 20 mL of methanol and 30 mL of acetonitrile. Adjust with glacial acetic acid to a pH of 4.0.

Standard stock solution: Transfer about 25 mg of USP Acetazolamide RS, accurately weighed, to a 50-mL volumetric flask, add 5.0 mL of 0.5 N sodium hydroxide, and mix to dissolve. Dilute with water to volume, and mix.

Standard solution: 250 µg/mL of USP Acetazolamide RS from the Standard stock solution in water

Sample solution: 250 µg/mL of acetazolamide from Oral Suspension in Mobile phase. Agitate the container of Oral Suspension for 30 min on a rotating mixer, remove a 5-mL sample, and store in a clear glass vial at -70° until analyzed. At the time of analysis, remove the sample from the freezer, allow to reach room temperature, and mix with a vortex mixer for 30 s. Pipet 1.0 mL of this solution to a 100-mL volumetric flask, and dilute with Mobile phase to volume.

2.2 Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 254 nm

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

Flow rate: 2 mL/min

Injection volume: 20 µL

2.3 System suitability

Sample: Standard solution

[NOTE-The retention time for the acetazolamide peak is about 3 min.]

Suitability requirements

Relative standard deviation: NMT 1.1% for replicate injections

2.4 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of acetazolamide (C₄H₆N₄O₃S₂) in the portion of Oral Suspension taken:

Result = (r_U/r_S) x (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 Acetazolamide RS in the Standard solution (µg/mL)

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

Acceptance criteria: 90.0%-110.0%

3 SPECIFIC TESTS

PH (791): 4.0-5.0 (Vehicle for Oral Solution and Vehicle for Oral Suspension), 3.1-3.9 (Cherry Syrup)

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 60 days after the day on which it was compounded when stored at controlled room temperature, or in a refrigerator

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

USP REFERENCE STANDARDS (11)

USP Acetazolamide RS