General Notices
DEFINITION
Calamine Ointment contains 15% w/w of Calamine in a suitable hydrophobic basis.
Extemporaneous preparation
The following formula and directions apply.
Calamine, finely sifted……………………..150g
White Soft Paraffin………………………….850g
Triturate the Calamine with part of the White Soft Paraffin until smooth and gradually incorporate the remainder of the White Soft Paraffin.
The ointment complies with the requirements stated under Topical Semi-solid Preparations and with the following requirements.
Content of zinc, Zn
7.8 to 9.4% w/w.
IDENTIFICATION
The residue obtained in the Assay is yellow when hot and white when cool.
ASSAY
Gently heat 1 g until the basis is completely volatilised or charred, increase the heat until all the carbon is removed and ignite the residue until, after further ignition, two successive weighings do not differ by more than 0.2% of the weight of the residue. Each g of residue is equivalent to 0.8034 g of Zn.
