Tretinoin Topical Solution

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

Tretinoin Topical Solution is a solution of Tretinoin in a suitable nonaqueous, hydrophilic solvent. It contains NLT 90.0% and NMT 135.0% of the labeled amount of tretinoin (C₂₀H₂₈O₂) (w/w). 

2 IDENTIFICATION

2.1 A.

Sample solution: Mix 5 mL of Topical Solution and 5 mL of water.

Acceptance criteria: A voluminous yellow precipitate is formed.

2.2 B.

Sample solution: Proceed as directed for the Sample solution in the Assay.

Analysis: Measure the absorbance between 300 and 450 nm.

Acceptance criteria: The Sample solution exhibits maxima and minima at the same wavelengths as that of a similar solution of USP Tretinoin RS, concomitantly measured.

3 ASSAY

PROCEDURE

Avoid exposure to strong light, and use low-actinic glassware.

Acidified isopropyl alcohol: Dilute 1 mL of 0.01 N hydrochloric acid with isopropyl alcohol to make 1000 mL..

Standard solution: 3.75 µg/mL of USP Tretinoin RS in Acidified isopropyl alcohol

Sample solution: Nominally 3.75 µg/mL of tretinoin in Acidified isopropyl alcohol from Topical Solution

Instrumental conditions

Mode: UV

Analytical wavelength: 352 nm

Cell: 1 cm

Blank: Acidified isopropyl alcohol

Analysis

Samples: Standard solution and Sample solution

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

                         Result = (A_U/A_S) x (C_S/C_U) × 100

A_U = absorbance of the Sample solution

A_S = absorbance of the Standard solution 

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

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

Acceptance criteria: 90.0%-135.0%

4 OTHER COMPONENTS

ALCOHOL DETERMINATION (611): 90.0%-110.0% of the labeled amount of alcohol (C₂H₅OH)

5 ADDITIONAL REQUIREMENTS

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

USP REFERENCE STANDARDS (11)

USP Tretinoin RS