Famciclovir 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

Famciclovir Compounded Oral Suspension contains NLT 90.0% and NMT 110.0% of the labeled amount of famciclovir (C₁₄H₁₉N₅O₄).

Prepare Famciclovir Compounded Oral Suspension 100 mg/mL as follows (see Pharmaceutical Compounding—Nonsterile Preparations 〈795〉).

^a Famvir 500-mg tablets, Novartis Pharmaceuticals Corporation, East Hanover, NJ.

^b Perrigo Laboratories, Allegan, MI.

Place the Famciclovir tablets in a suitable container and comminute to a fine powder. Wet the powder with a small amount of Vehicle and triturate to make a smooth paste. Add the Vehicle to make the contents pourable. Transfer contents stepwise and quantitatively to a calibrated container using the Vehicle. Add sufficient Vehicle to bring to final volume. Shake to mix well.

2 ASSAY

2.1 Procedure

Solution A: 5 mM monobasic potassium phosphate. Adjust with phosphoric acid to a pH of 3.0. Pass through a nylon filter of 0.45-μm pore size, and degas.

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

Diluent: Water. Adjust with phosphoric acid to a pH of 3.0.

Standard stock solution: 10 mg/mL of USP Famciclovir RS in Diluent. Sonicate to mix well. Store at 2°– 8°.

Standard solution: Transfer 1.0 mL of the Standard stock solution to a 250-mL volumetric flask, dilute with Diluent to volume, and mix well.

Transfer an aliquot to a centrifuge tube, and centrifuge at 2°– 8° for 5 min at 14,000 rpm. Transfer the supernatant to an amber vial and store at 2°–8°.

Sample solution: Transfer 1.0 mL of Oral Suspension to a 10-mL volumetric flask, dilute with Diluent to volume, and sonicate to mix well. Transfer 1.0 mL of the resultant solution to a 250-mL volumetric flask, dilute with Diluent to volume, and mix well. Transfer an aliquot to a centrifuge tube, and centrifuge at 2°–8° for 5 min at 14,000 rpm. Transfer the supernatant to an amber vial and store at 2°–8°.

2.2 Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV-Vis 310 nm

Column: 4.6-mm × 15-cm; 5-μm packing L7

2.3 Temperatures

Column: 30°

Autosampler: 5°

Flow rate: 1.0 mL/min

Injection volume: 20 μL

2.4 System suitability

Sample: Standard solution

[Note—The retention time for famciclovir is about 4.5 min.]

2.5 Suitability requirements

Tailing factor: NMT 2.0

Relative standard deviation: NMT 2.0% for replicate injections

2.6 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of famciclovir (C₁₄H₁₉N₅O₄) in the portion of Oral Suspension taken:

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

r_{​​​​​​​U} = peak response of famciclovir from the Sample solution

r_S = peak response of famciclovir from the Standard solution

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

C_{​​​​​​​U} = nominal concentration of famciclovir in the Sample solution (mg/mL)

Acceptance criteria: 90.0%–110.0%

3 SPECIFIC TESTS

pH 〈791〉: 4.3–6.0

4 ADDITIONAL REQUIREMENTS

Packaging and Storage: Package in tight, light-resistant, plastic containers. Store in a refrigerator (2°–8°) or at controlled room temperature.

Beyond-Use Date: NMT 90 days after the date on which it was compounded when stored in a refrigerator (2°–8°) or 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 Famciclovir RS