Edition: BP 2025 (Ph. Eur. 11.6 update)
General Notices
Action and use
Antiseptic.
DEFINITION
Cetrimide Cream contains the stated percentage w/w of Cetrimide in a suitable basis.
Extemporaneous preparation
The following formula and directions apply.
Cetrimide 5 g, or a sufficient quantity
Cetostearyl Alcohol 50 g
Liquid Paraffin 500 g
Purified Water, freshly boiled and cooled Sufficient to produce 1000 g
Melt the Cetostearyl Alcohol and heat with the Liquid Paraffin to about 60°. Dissolve the Cetrimide in sufficient Purified Water to produce about 450 g. Add the aqueous solution to the oily phase when both are at about 60° and mix. Stir gently until cool, add sufficient of the Purified Water to produce 1000 g and mix.
The cream complies with the requirements stated under Topical Semi-solid Preparations and with the following requirements.
Content of cetrimide, C17H38BrN
88.0 to 106.0% of the stated amount.
IDENTIFICATION
Mix 1 g with 50 mL of water. The diluted cream complies with the following tests.
A. To 10 mL add 2 mL of potassium hexacyanoferrate(III) solution. A yellow precipitate is produced.
B. Shake 3 mL of water with 1 mL of 1M sulfuric acid, 2 mL of chloroform and 0.5 mL of methyl orange solution. Add 2 mL of the diluted cream, shake and allow to separate. A yellow colour develops in the chloroform layer.
ASSAY
To a quantity containing 5 mg of Cetrimide add 10 mL of hot water and shake gently until dispersed. Add 5 mL of 1M sulfuric acid, 20 mL of chloroform and 0.25 mL of dimethyl yellow solution and titrate with 0.001M dioctyl sodium sulfosuccinate VS. Each mL of 0.001M dioctyl sodium sulfosuccinate VS is equivalent to 0.3364 mg of C17H38BrN.
LABELLING
The strength is stated as the percentage w/w of Cetrimide.
When Cetrimide Cream is prescribed or demanded, no strength being stated, a cream containing 0.5% w/w shall be dispensed or supplied.
