Calcium Hydroxide Topical Solution
» Calcium Hydroxide Topical Solution is a solution containing, in each 100 mL, not less than 140 mg of calcium hydroxide [Ca(OH)2].
Prepare Calcium Hydroxide Topical Solution as follows (see Pharmaceutical Compounding—Nonsterile Preparations 795):
Calcium Hydroxide 3 g
Purified Water 1000 mL
Add the Calcium Hydroxide to 1000 mL of cool Purified Water, and agitate the mixture vigorously and repeatedly during 1 hour. Allow the excess calcium hydroxide to settle. Dispense only the clear supernatant.
note—The solubility of calcium hydroxide, which varies with the temperature at which the solution is stored, is about 170 mg per 100 mL at 15 and less at a higher temperature. The official concentration is based upon a temperature of 25.
The undissolved portion of the mixture is not suitable for preparing additional quantities of Calcium Hydroxide Topical Solution.
Packaging and storage— Preserve in well-filled, tight containers, at a temperature not exceeding 25.
A: It absorbs carbon dioxide from the air, a film of calcium carbonate forming on the surface of the liquid.
B: When heated, it becomes turbid, owing to the separation of calcium hydroxide.
C: It responds to the tests for Calcium 191.
Alkalies and their carbonates— A portion of it, saturated with carbon dioxide and subsequently boiled, is neutral in reaction.
Assay— Pipet 100 mL of Topical Solution into a suitable container, add 50 mL of water, 15 mL of 1 N sodium hydroxide, and 300 mg of hydroxy naphthol blue, and titrate with 0.05 M edetate disodium VS to a blue endpoint. Each mL of 0.05 M edetate disodium is equivalent to 3.705 mg of calcium hydroxide [Ca(OH)2].
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