Potassium hydroxide

• BPPotassium Hydroxide
• JPPotassium Hydroxide
• Ph. Eur.Potassium Hydroxide
• USP–NFPotassium Hydroxide

Caustic potash; kalii hydroxidum; potassa; potassium hydrate; E525

Potassium hydroxide · [1310-58-3]

UNII WZH3C48M4T · PubChem CID 14797

KOH · 56.11

pH adjuster, buffering agent

Typical concentrations: — · Dosage forms: Liquid, Semi-solid

Used as an alkalising agent and pH adjuster in parenteral, oral and topical preparations, usually added as a dilute solution in the amount needed to reach the target pH. It is used to neutralise carbomers to form gels, to saponify fatty acids in the in-situ formation of soaps in creams and liquid soaps, and to form potassium salts of acidic drugs.

White or almost white, hard, brittle, deliquescent sticks, pellets, flakes or fused masses with a crystalline fracture. It is strongly alkaline and corrosive.

Assay

not less than 85% KOH (the remainder is mostly water and potassium carbonate)

Density

about 2.04 g/cm³

Solubility

very soluble in water with strong evolution of heat; freely soluble in ethanol

pH

about 13.5 (0.1 M aqueous solution)

Deliquescent; on exposure to air it absorbs water and carbon dioxide, forming potassium carbonate. Store in a tightly closed, non-metallic container in a dry place. Concentrated solutions slowly attack glass.

A strong base that reacts violently with acids. It attacks aluminium, zinc and tin with evolution of hydrogen, liberates ammonia from ammonium salts and hydrolyses esters and many other drugs and excipients.

Manufactured by electrolysis of aqueous potassium chloride solution; the resulting solution is evaporated and the solid is cast or formed into pellets or flakes.

Highly corrosive to the skin, eyes and mucous membranes; ingestion causes severe burns of the mouth, oesophagus and stomach, and eye contact can cause permanent damage. In finished products it is present only in neutralised form and at small levels, so it poses no toxicity concern.

Wear gloves, goggles or a face shield and protective clothing. Always add the solid slowly to water, with cooling and stirring, never water to the solid, because dissolution is strongly exothermic. Spills on the skin should be washed with plenty of water.

GRAS listed. Accepted as a food additive in Europe (E525). Included in the FDA Inactive Ingredient Database (including injections and oral and topical preparations) and in parenteral and non-parenteral medicines licensed in Europe.

Potassium carbonate; sodium hydroxide.

Because the solid takes up water and carbon dioxide, its effective KOH content varies; when an exact quantity is needed, use a standardised solution or titrate to the required pH rather than relying on the weighed amount.