Packaging and storage— Preserve in collapsible ophthalmic ointment tubes.

USP Reference standards á11ñ— USP Chlortetracycline Hydrochloride RS.

Sterility á71ñ: meets the requirements.

Minimum fill á755ñ: meets the requirements.

Water,Method Iá921ñ: not more than 0.5%,20mLof a mixture of toluene and methanol (7:3)being used in place of methanol in the titration vessel.

Metal particles— It meets the requirements of the test for Metal Particles in Ophthalmic Ointments á751ñ.

Assay— Proceed as directed under Antibiotics—Microbial Assays á81ñ,using an accurately weighed quantity of Ophthalmic Ointment,equivalent to about 10mg of chlortetracycline hydrochloride,shaken in a separator with about 50mLof ether,and extracted with four 20-mLportions of 0.01Nhydrochloric acid.Combine the aqueous extracts in a 100-mLvolumetric flask,dilute with 0.01Nhydrochloric acid to volume,and mix.Dilute this stock solution quantitatively and stepwise with water to 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 459

Phone Number:1-301-816-8335