DEFINITION
Zinc and Ichthammol Cream contains 5% w/w of Ichthammol dispersed in a suitable basis of which about 82% w/w is Zinc Cream.
Extemporaneous preparation
The following formula and directions apply.
| Ichthammol | 50 g |
| Cetostearyl Alcohol | 30 g |
| Wool Fat | 100 g |
| Zinc Cream Sufficient to produce | 1000 g |
Melt together the Wool Fat and the Cetostearyl Alcohol with the aid of gentle heat, triturate the mixture with 800 g of Zinc Cream until smooth, incorporate the Ichthammol, add sufficient Zinc Cream 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 zinc oxide, ZnO
23.4 to 29.3% w/w.
ASSAY
Gently heat 0.4 g, taking precautions to avoid loss caused by spitting, until the basis is completely volatilised or charred, cool, dissolve the residue in 10 mL of 2M sulfuric acid, add 40 mL of water, adjust the solution to about pH 10 with 5M ammonia, add 10 mL of ammonia buffer pH 10.9 and titrate with 0.05M disodium edetate VS using mordant
