Tretinoin Cream

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

Tretinoin Cream contains NLT 90.0% and NMT 120.0% of the labeled amount of tretinoin (C₂₀H₂₈O₂).

2 IDENTIFICATION

A. The retention time of the major peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.

3 ASSAY

PROCEDURE

Avoid exposure to strong light, and use low-actinic glassware in the performance of the following procedure. Use stabilized tetrahydrofuran in the preparation of the Standard solution and the Sample solution.

Diluted phosphoric acid: Dilute 10 mL of phosphoric acid with water to 100 mL..

Buffer: 1.38 g/L of monobasic sodium phosphate in water. Adjust with Diluted phosphoric acid to a pH of 3.0.

Diluent A: Water and Diluted phosphoric acid (9:1)

Diluent B: Tetrahydrofuran and Diluent A (3:2)

Mobile phase: Tetrahydrofuran and Buffer (42:58)

Standard stock solution: 0.4 mg/mL of USP Tretinoin RS in tetrahydrofuran

Standard solution: 4 µg/mL of USP Tretinoin RS in Diluent B from Standard stock solution

Sample stock solution: Nominally 20 µg/mL, of tretinoin in tetrahydrofuran prepared as follows. Transfer a quantity of Cream, equivalent to 1.0 mg of tretinoin, into a 50-mL volumetric flask, and add 20.0 mL of tetrahydrofuran. Shake the flask to disperse the cream, dilute with tetrahydrofuran to volume, mix, and filter if necessary.

Sample solution: 4 µg/mL of tretinoin in Diluent B from Sample stock solution

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 365 nm

Column: 3.9-mm x 15-cm; 4-um packing L1

Flow rate: 1 mL/min

Injection volume: 25 µL

System suitability

Sample: Standard solution

Suitability requirements

Relative standard deviation: NMT 2.0%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of tretinoin (C₂₀H₂₈O₂) in the portion of Cream taken:

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

r_U = peak response from the Sample solution

r_S = peak response from the Standard solution

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

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

Acceptance criteria: 90.0%-120.0%

4 PERFORMANCE TESTS

MINIMUM FILL (755): Meets the requirements

5 ADDITIONAL REQUIREMENTS

PACKAGING AND STORAGE: Preserve in collapsible tubes or in tight, light-resistant containers.

USP REFERENCE STANDARDS (11)

USP Tretinoin BS