Betamethasone Dipropionate Ointment
» Betamethasone Dipropionate Ointment contains an amount of betamethasone dipropionate (C28H37FO7) equivalent to not less than 90.0 percent and not more than 110.0 percent of the labeled amount of betamethasone (C22H29FO5), in a suitable ointment base.
Packaging and storage— Preserve in collapsible tubes or tight containers. Store at 25, excursions permitted between 15 and 30. Protect from freezing.
Thin-layer chromatographic identification test 201
Test solution— Transfer about 1.5 g of Ointment to a glass-stoppered, 50-mL centrifuge tube. Add 15 mL of methanol–hydrochloric acid solution prepared by mixing 1 volume of dilute hydrochloric acid (1 in 120) with 4 volumes of methanol. Shake to obtain a homogeneous mixture. Add 30 mL of solvent hexane, mix for 10 minutes, and centrifuge. Using a suitable syringe, transfer the lower aqueous phase to a second centrifuge tube, add about 20 mL of water, and mix. Extract this aqueous mixture with chloroform by shaking, centrifuging, and removing the lower, chloroform phase with a syringe. Evaporate the chloroform on a steam bath with the aid of a stream of nitrogen to dryness, cool, and dissolve the residue in chloroform to obtain a solution containing about 150 µg of betamethasone dipropionate per mL.
Standard solution: USP Betamethasone Dipropionate RS in chloroform containing 150 µg per mL.
Application volume: 40 µL.
Developing solvent system: a mixture of chloroform and acetone (7:1).
Procedure— Proceed as directed in the chapter.
Minimum fill 755: meets the requirements.
Mobile phase— Prepare as directed in the Assay under Betamethasone Dipropionate.
Internal standard solution and Standard preparation— Prepare as directed in the Assay under Betamethasone Dipropionate Cream, except to use alcohol containing acetic acid (1 in 1000) as the solvent.
Assay preparation— Transfer an accurately weighed quantity of Ointment, equivalent to about 2 mg of betamethasone dipropionate, to a capped 50-mL centrifuge tube. Add 5.0 mL of Internal standard solution and 10.0 mL of alcohol containing acetic acid (1 in 1000). Heat in a water bath at 70, shaking intermittently until the assay specimen melts. Remove from the bath, and shake vigorously until the ointment has solidified. Repeat the heating and shaking operation. Proceed as directed for Assay preparation in the Assay under Betamethasone Dipropionate Cream, beginning with “Freeze in an ice-methanol bath.”
Procedure— Proceed as directed for Procedure in the Assay under Betamethasone Dipropionate Cream.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Daniel K. Bempong, Ph.D.
Senior Scientist
(MDPS05) Monograph Development-Pulmonary and Steroids
Reference Standards Lili Wang, Technical Services Scientist
USP32–NF27 Page 1662
Pharmacopeial Forum: Volume No. 29(5) Page 1430
Chromatographic Column—
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.