Packaging and storage— Preserve in collapsible tubes or other tight containers, and avoid exposure to excessive heat.

USP Reference standards 11— USP Gentamicin Sulfate RS.

Identification— Shake a quantity of Ointment, equivalent to about 5 mg of gentamicin, with a mixture of 200 mL of chloroform and 5 mL of water. Allow to separate, and filter the aqueous layer: the filtrate so obtained meets the requirements of the Identification test under Gentamicin Injection.

Minimum fill 755: meets the requirements.

Water, Method I 921: not more than 1.0%, 20 mL of a mixture of toluene and methanol (7:3) being used in place of methanol in the titration vessel.

Residual solvents 467: meets the requirements.

Assay— Proceed with Ointment as directed under Antibiotics—Microbial Assays 81, using an accurately weighed quantity of Ointment, equivalent to about 1 mg of gentamicin, shaken with about 50 mL of ether in a separator, and extracted with four 20-mL portions of Buffer No. 3. Combine the aqueous extracts, and dilute quantitatively and stepwise with Buffer No. 3 to obtain a Test Dilution having a concentration assumed to be equal to the median dose level of the Standard.

Expert Committee : (MDANT05) Monograph Development-Antibiotics

USP29–NF24 Page 995

Phone Number : 1-301-816-8223