NOTE: This monograph has been developed to cover unlicensed formulations.
Action and use
Keratolytic.
DEFINITION
Salicylic Acid Ointment contains Salicylic Acid in a suitable water-emulsifying basis.
The ointment complies with the requirements stated under Topical Semi-solid Preparations and with the following requirements. Where appropriate, the ointment also complies with the requirements stated under Unlicensed Medicines.
Content of salicylic acid, C7H6O3
95.0 to 105.0% of the stated amount.
IDENTIFICATION
Shake 1 g with 10 mL of water, filter and add to the filtrate iron(III) chloride solution R1; an intense reddish violet colour is produced which persists on the addition of 6M acetic acid. Add 2M hydrochloric acid; the colour disappears and a white, crystalline precipitate is produced.
ASSAY
Dissolve a quantity of the ointment containing 0.25 g of Salicylic Acid in a mixture of 20 mL of ethanol (96%), previously neutralised to phenol red solution, and 20 mL of ether and titrate with 0.1M sodium hydroxide VS using phenol red solution
as indicator. Each mL of 0.1M sodium hydroxide VS is equivalent to 13.81 mg of C7H6O3
