Zonisamide 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

Zonisamide Compounded Oral Suspension contains NLT 90.0% and NMT 110.0% of the labeled amount of zonisamide (C₈H₈N₂O₃S).

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

^a Zonisamide 100-mg capsules, Mylan, Morgantown, WV.

^b Paddock Laboratories, Minneapolis, MN.

Empty the capsules, and pour the contents into a mortar or other suitable container. Crush the capsule contents into a fine powder using a pestle or other mechanical means. Wet the powder with a small amount of Vehicle, and triturate to make a smooth paste. Add the Vehicle to make the mortar contents pourable. Transfer the contents, stepwise and quantitatively, to a calibrated container using the remainder of the Vehicle. Add sufficient Vehicle to bring to final volume, and mix well. [CAUTION-Avoid skin contact or inhalation of zonisamide by using protective gloves and a fume hood or surgical mask.]

2 ASSAY

2.1 PROCEDURE

Solution A: 50 mM sodium phosphate adjusted with phosphoric acid to a pH of 2.8

Mobile phase: Acetonitrile and Solution A (25:75)

Standard stock solution: 1 mg/mL of USP Zonisamide RS in Mobile phase. Sonicate for 10 min.

Standard solution: Transfer 1 mL of the Standard stock solution to a 10-mL volumetric flask, dilute with Mobile phase to volume, and mix well. Centrifuge an aliquot of the solution for 10 min at 13,000 rpm.

Sample solution: Shake each bottle of Oral Suspension thoroughly. Transfer 1 mL of Oral Suspension to a 10-mL volumetric flask, dilute with Mobile phase to volume, and mix well. Vortex for 30 s, and sonicate for 10 min. Transfer 1 mL of the resultant solution to a 10-mL volumetric flask, and dilute with Mobile phase to volume. Centrifuge an aliquot of the solution for 10 min at 13,000 rpm.

2.2 Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 264 nm

Column: 4.6-mm x 15-cm; 3.5-µm packing L1

Column temperature: 32°

Flow rate: 1.0 mL/min

Injection volume: 50 µL

2.3 System suitability

Sample: Standard solution

[NOTE-The retention time for zonisamide is about 4.6 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 zonisamide (C₈H₈N₂O₃S) in the portion of Oral Suspension taken:

Result = (r_U/r_S) x (C_S/C_U) x 100

r_U = peak response of zonisamide from the Sample solution

r_S = peak response of zonisamide from the Standard solution

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

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

Acceptance criteria: 90.0%-110.0%

3 SPECIFIC TESTS

PH (791): 3.9-4.9

4 ADDITIONAL REQUIREMENTS

4.1 PACKAGING AND STORAGE

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

4.2 BEYOND-USE DATE

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

4.3 LABELING

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

4.4 USP REFERENCE STANDARDS (11)

USP Zonisamide RS