International Numbering System (INS) for Food Additives: 526
Food additives Europe numbers: E526
Functional Category
Alkalizing agent; astringent; therapeutic agent.
Applications in Pharmaceutical Formulation
Calcium hydroxide is a strong alkali and is used as a pharmaceutical pH adjuster/buffer and antacid in topical medicinal ointments, creams, lotions, and suspensions, often as an aqueous solution (lime water).(1,2) It forms calcium soaps of fatty acids, which produce water-in-oil emulsions (calamine liniment), and it is also used as a topical astringent.(3,4) Calcium hydroxide is a common cosmetic ingredient in hairstraightening and hair-removal products, and in shaving preparations.(1) In dentistry, it is used as a filling agent and in dental pastes to encourage deposition of secondary dentine.(5) Calcium hydroxide was traditionally used as an escharotic in Vienna Paste
Description
Calcium hydroxide occurs as a white or almost white, crystalline or granular powder. It has a bitter, alkaline taste. Calcium hydroxide readily absorbs carbon dioxide to form calcium carbonate
Stability and Storage Conditions
Calcium hydroxide should be stored in an airtight container, in a cool, dry, well-ventilated place. Calcium hydroxide powder may be sterilized by heating for 1 hour at a temperature of at least 1608C.
Incompatibilities
Incompatible with strong acids, maleic anhydride, phosphorus, nitroethane, nitromethane, nitroparaffins, and nitropropane. Calcium hydroxide can be corrosive to some metals.
Safety
Calcium hydroxide is used in oral and topical pharmaceutical formulations. It is mildly toxic by ingestion. In the pure state, calcium hydroxide is a severe skin, eye, and respiratory irritant, and it is corrosive, causing burns. Typical exposure limits are TVL 5 mg/m3 in air.(7) LD50 (mouse, oral): 7.3 g/kg LD50 (rat, oral): 7.34 g/kg