Betamethasone and Clioquinol Ointment

Definition

 

Betamethasone and Clioquinol Ointment contains Betamethasone Valerate and Clioquinol, the latter in very fine powder , in a suitable basis.

 

The ointment complies with the requirements stated under Topical Semi-solid Preparations and with the following requirements.

 

Content of betamethasone, C22H29FO5

 

90.0 to 110.0% of the stated amount.

 

Content of clioquinol, C9H5ClINO

 

90.0 to 110.0% of the stated amount.

 

Identification

 

A.    Complies with test A for Identification described under Betamethasone and Clioquinol Cream but preparing the solutions in the following manner. For solution (1) disperse a quantity of the ointment containing the equivalent of 1 mg of betamethasone with 10 ml of methanol  by heating on a water bath until the methanol begins to boil. Shake vigorously, cool in ice and filter. Evaporate the filtrate to dryness in a current of nitrogen and dissolve the residue in 0.5 ml of chloroform. Solution (2) contains 0.24% w/v of betamethasone valerate BPCRS in chloroform.

 

B.    In the Assay for betamethasone the chromatogram obtained with solution (2) shows a peak with the same retention time as the peak due to betamethasone valerate in the chromatogram obtained with solution (1).

 

C.    In the Assay for clioquinol the chromatogram obtained with solution (2) shows a peak with the same retention time as the peak due to clioquinol in the chromatogram obtained with solution (1).

 

Assay

 

For betamethasone

 

Carry out the method for liquid chromatography, Appendix III D, using the following solutions. For solution (1) mix 10 ml of a solution containing 0.024% w/v of betamethasone valerate BPCRS and 0.0012% w/v of betamethasone 21-valerate BPCRS in ethanol  (65%) with 5 ml of a 0.072% w/v solution of beclometasone dipropionate BPCRS (internal standard) in ethanol  (65%) and dilute to 50 ml with ethanol  (65%). For solution (2) disperse a quantity of the ointment containing the equivalent of 2 mg of betamethasone in 100 ml of hot hexane, cool, extract with 20 ml of ethanol  (65%) and filter the lower, ethanolic layer through absorbent cotton previously washed with ethanol  (65%); repeat the extraction of the hexane mixture with two 10 ml quantities of ethanol  (65%), filtering each extract in turn through the absorbent cotton and dilute the combined filtrates to 50 ml with ethanol  (65%). Prepare solution (3) in the same manner as solution (2) but add 5 ml of the 0.072% w/v solution of the internal standard in ethanol  (65%) before diluting to 50 ml.

 

The chromatographic procedure may be carried out using (a) a stainless steel column (10 cm 5 mm) packed with stationary phase C (5 µm) (Spherisorb ODS 1 is suitable) and maintained at 60, (b) as the mobile phase with a flow rate of 2 ml per minute a mixture of absolute ethanol  and water  adjusted so that the resolution factor  between the peaks due to betamethasone valerate (retention time about 5 minutes) and betamethasone 21-valerate (retention time about 7 minutes) is more than 1.0 (a mixture of 42 volumes of absolute ethanol  and 58 volumes of water  is usually suitable) and (c) a detection wavelength of 238 nm.

 

Calculate the content of C22H29FO5 in the ointment using the declared content of C22H29FO5 in betamethasone valerate BPCRS.

 

For clioquinol

 

Carry out the Assay described under Betamethasone and Clioquinol Cream.

 

Storage

 

Betamethasone and Clioquinol Ointment should be protected from light.

 

Labelling

 

The quantity of active ingredient with respect to Betamethasone Valerate is stated in terms of the equivalent amount of betamethasone.