Minoxidil Topical Solution, chemical structure, molecular formula, Reference Standards

Minoxidil Topical Solution

»Minoxidil Topical Solution contains not less than 90.0percent and not more than 110.0percent of the labeled amount of minoxidil (C9H15N5O).

Packaging and storage— Preserve in tight containers.

USP Reference standards á11ñ— USP Minoxidil RS.

Identification—

A: Infrared Absorption á197Mñ—

Test specimen— Evaporate 1mLof the Topical Solution under a stream of nitrogen while heating at 50

B: The retention time of the major peak for minoxidil in the chromatogram of the Assay preparationcorresponds to that of the Standard preparation,as obtained in the Assay.

Assay—

Mobile phase,Internal standard solution,Standard preparation ,and Chromatographic system—Proceed as directed in the Assayunder Minoxidil.

Assay preparation— Transfer an accurately measured volume of Topical Solution,equivalent to about 100mg of minoxidil,to a 10-mLvolumetric flask,dilute with Mobile phaseto volume,and mix.Transfer 0.5mLof this solution to a suitable vial,add 20.0mLof Internal standard solution,and mix.

Procedure— Proceed as directed for Procedurein the Assayunder Minoxidil.Calculate the quantity,in mg,of minoxidil (C9H15N5O)in each mLof the Topical Solution taken by the formula:

(400C/V)(RU/RS),

in which Cis the concentration,in mg per mL,of USP Minoxidil RSin the Standard preparation,Vis the volume,in mL,of the Topical Solution taken for the Assay preparation,and RUand RSare the ratios of the minoxidil peak to that of the internal standard obtained from the Assay preparationand the Standard preparation,respectively.

Auxiliary Information— Staff Liaison:Andrzej Wilk,Ph.D.,Senior Scientific Associate

Expert Committee:(PA5)Pharmaceutical Analysis 5

USP28–NF23Page 1301

Phone Number:1-301-816-8305