Tretinoin Topical Solution
» Tretinoin Topical Solution is a solution of Tretinoin in a suitable nonaqueous, hydrophilic solvent. It contains not less than 90.0 percent and not more than 135.0 percent of the labeled amount of C20H28O2 (w/w).
Packaging and storage— Preserve in tight, light-resistant containers.
A: Mix 5 mL of Topical Solution with 5 mL of water: a voluminous yellow precipitate is formed.
B: The absorption spectrum, obtained between wavelengths of 300 nm and 450 nm, of the solution employed for measurement of absorbance in the Assay exhibits maxima and minima at the same wavelengths as that of a similar solution of USP Tretinoin RS, concomitantly measured.
Alcohol content 611: between 90.0% and 110.0% of the labeled amount of C2H5OH.
Assay— [note—Avoid exposure to strong light, and use low-actinic glassware in the performance of the following procedure.] Transfer to a 100-mL volumetric flask an accurately weighed quantity of Topical Solution, equivalent to about 375 µg of tretinoin, dilute with acidified isopropyl alcohol (prepared by mixing 1 mL of 0.01 N hydrochloric acid with isopropyl alcohol to make 1000 mL of solution) to volume, and mix. Dissolve an accurately weighed quantity of USP Tretinoin RS in the acidified isopropyl alcohol, and dilute quantitatively and stepwise with the same solvent to obtain a Standard solution having a known concentration of about 3.75 µg per mL. Concomitantly determine the absorbances of both solutions in 1-cm cells at the wavelength of maximum absorbance at about 352 nm, with a suitable spectrophotometer, using the acidified isopropyl alcohol as the blank. Calculate the quantity, in µg, of C20H28O2 in the portion of Topical Solution taken by the formula:
100C(AU / AS)
in which C is the concentration, in µg per mL, of USP Tretinoin RS in the Standard solution, and AU and AS are the absorbances of the solution from the Topical Solution and the Standard solution, respectively.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Feiwen Mao, M.S.
(MDOOD05) Monograph Development-Ophthalmics Oncologics and Dermatologicals
Reference Standards Lili Wang, Technical Services Scientist
USP32–NF27 Page 3780
Chromatographic Column—
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.