Minoxidil Tablets
»Minoxidil Tablets contain 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.
Identification—
Transfer a portion of finely powdered Tablets,equivalent to about 10mg of minoxidil,to a separator.Add 25mLof water,and extract with three 15-mLportions of chloroform.Combine the chloroform extracts,and evaporate with the aid of a stream of nitrogen.Wash the inside of the container with about 5mLof alcohol,add 300mg of potassium bromide,and evaporate under vacuum at 50
until dry:the IRabsorption spectrum of a potassium bromide dispersion prepared from the residue so obtained exhibits maxima at the same wavelengths as that of a similar preparation of USP Minoxidil RS.
until dry:the IRabsorption spectrum of a potassium bromide dispersion prepared from the residue so obtained exhibits maxima at the same wavelengths as that of a similar preparation of USP Minoxidil RS.
Dissolution á711ñ—
Medium:
pH7.2phosphate buffer (see under Buffer Solutionsin the section Reagents,Indicators,and Solutions);900mL.
Apparatus 1:
75rpm.
Time:
15minutes.
Procedure—
Determine the amount of C9H15N5Odissolved from UVabsorbances at the wavelength of maximum absorbance of filtered portions of the solution under test,suitably diluted with Dissolution Medium,if necessary,in comparison with a Standard solution having a known concentration of USP Minoxidil RSin the same medium.For Tablets containing up to 10mg of minoxidil,measurement is made at about 231nm;for Tablets containing more than 10mg,the wavelength used is about 287nm.
Tolerances—
Not less than 75%(Q)of the labeled amount of C9H15N5Ois dissolved in 15minutes.
Uniformity of dosage units á905ñ:
meet the requirements.
Assay—
Mobile phase
,Internal standard solution,Standard preparation,and Chromatographic system—Proceed as directed in the Assayunder Minoxidil.
Assay preparation—
Weigh and finely powder not less than 10Tablets.To an accurately weighed portion of the powder,equivalent to about 5mg of minoxidil,add 20.0mLof Internal standard solution,shake for 5minutes,and centrifuge.
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