Nitroglycerin Ointment
»Nitroglycerin Ointment is Diluted Nitroglycerin in a suitable ointment base.It contains not less than 90.0percent and not more than 115.0percent of the labeled amount of Nitroglycerin (C3H5N3O9).
Packaging and storage— Preserve in tight containers.
Labeling— Label multiple-dose containers with a direction to close tightly,immediately after each use.
Identification— The retention time of the major peak obtained from the Assay preparationcorresponds to that from the Standard preparationas obtained in the Assay.
Minimum fill á755ñ: meets the requirements.
Homogeneity— In the case of single-dose containers,perform the Assayon specimens from each of 10containers.In the case of multiple-dose containers,perform the Assayon one specimen from the top and one from the bottom of each of 5containers.Each specimen contains not less than 90.0%and not more than 110.0%of the mean value.
Assay—
Mobile phase,Standard preparation,andChromatographic system— Proceed as directed in the Assayunder Diluted Nitroglycerin.
Assay preparation— Transfer an accurately weighed portion of Ointment,equivalent to about 2.0mg of nitroglycerin,to a glass-stoppered,50-mLconical flask,and add 25.0mLof Mobile phase.Immerse for 10minutes in a water bath maintained at a temperature of 50,shaking intermittently until the specimen becomes dispersed.Remove from the bath,and shake vigorously for 1minute to obtain a coagulated solid.Repeat the heating and shaking steps one more time and filter.
Procedure— Separately inject equal volumes of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg,of C3H5N3O9in the portion of Ointment taken by the formula:
25C(rU/rS)
in which Cis the concentration,in mg per mL,of nitroglycerin in the Standard preparation,and rUand rSare the peak responses of nitroglycerin 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 1386
Phone Number:1-301-816-8305
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