Packaging and storage— Preserve in collapsible tubes,or other well-closed containers.

USP Reference standards á11ñ— USP Amphotericin B RS.

Minimum fill á755ñ: meets the requirements.

Water,Method Iá921ñ: not more than 1.0%,20mLof a mixture of toluene and methanol (7:3)being used in place of methanol in the titration vessel.

Assay— Proceed as directed for amphotericin Bunder Antibiotics—Microbial Assays á81ñ,using an accurately weighed portion of Ointment,equivalent to about 30mg of amphotericin B,mixed with 10.0mLof ether in a suitable glass-stoppered conical flask and allowed to stand,with intermittent shaking,for 1hour.Add 20.0mLof dimethyl sulfoxide and shake by mechanical means for 10minutes.Dilute quantitatively and stepwise with dimethyl sulfoxide to a concentration of approximately 20µg per mL.Quantitatively dilute an accurately measured volume of this stock solution with Buffer No.10to obtain a Test Dilutionhaving a concentration assumed to be equal to the median dose level of the Standard.

Expert Committee:(PA7)Pharmaceutical Analysis 7

USP28–NF23Page 151

Phone Number:1-301-816-8335