Potassium hydroxide

Absorption

Potassium hydroxide (KOH) in aqueous solutions completely dissociates into K+ and OH- ions. Because of the neutralization of OH- by gastric HCl and the rapid blood pH regulation action (buffer capacity of extracellular body fluids, respiratory and renal compensation mechanisms), an alkalosis due to the OH- ions after KOH oral dosage in non-irritating conditions is thus prevented .
The uptake of potassium, in potassium hydroxide form, is much less than the oral uptake with therapeutic doses of KCl for treating potassium deficiency, of up to 10 g/day. Furthermore, the oral uptake of potassium from food/natural sources or from food additives is likely to be also much higher.

Toxicity

The Ld50 of potassium hydroxide in rats ranges from 0.273 - 1.230 g KOH/kg body weight/day.
Adverse effects include vomiting, diarrhea, skin blistering, gastrointestinal disturbance, and burns.
Potassium Hydroxide can irritate the lungs. Repeated exposure may cause bronchitis to develop with coughing, phlegm, and/or shortness of breath.

Description

Potassium hydroxide (KOH) is a strong base commonly used in organic chemistry. It is typically bought in pellet form as 85% KOH, 15% water. The pKa of the conjugate acid of potassium hydroxide is 15.7. The hydroxide ion is not only a base, it is also an effective nucleophile. It is capable of nucleophilic reactions such as the diplacement of alkyl halides to form alcohols, and the hydrolysis of esters and nitriles to carboxylic acids.

Chemical properties

Potassium hydroxide occurs as a white or nearly white fused mass. It is available in small pellets, flakes, sticks and other shapes or forms. It is hard and brittle and shows a crystalline fracture. Potassium hydroxide is hygroscopic and deliquescent; on exposure to air, it rapidly absorbs carbon dioxide and water with the formation of potassium carbonate. Soluble in water, alcohol, glycerol; slightly soluble in ether.

Indications

Medically, the microscopic examination of potassium hydroxide (KOH) preparations is utilized in the diagnosis of fungal hyphae or trichomonads .
Samples from hair, skin, or nail tissue are obtained by scraping with a scalpel, cotton-tipped applicator and are inoculated directly onto the KOH solution .
In addition to the above, potassium hydroxide is used as a softener for nail grooves .

Background

Medically, potassium hydroxide (KOH) is widely used in the wet mount preparation of various clinical specimens for microscopic visualization of fungi and fungal elements in skin, hair, nails, and even vaginal secretions.
Recently, it has been studied for efficacy and tolerability in the treatment of warts. It was determined that topical KOH solution was found to be a safe and effective treatment of plane warts.

Production Methods

Potassium hydroxide is made by the electrolysis of potassium chloride. Commercial grades may contain chlorides as well as other impurities.

Indications

Potassium hydroxide (KOH) is a strong alkali that digests proteins and epidermal debris. In one study, 10% solution was applied b.i.d. to each lesion for 30 days with excellent clearance. The side effects included stinging of the lesion and one case of secondary infection. Also reported were the occurrence of a hypertrophic scar as well as some persistent or transitory hyper- and hypopigmentation. The same authors who used the 5% KOH solution completed further studies and they found it to be as effective-yet with decreased side effects.

Health Hazard

Potassium hydroxide is a strongly alkaline, hydrophilic substance and therefore solid potassium hydroxide is highly corrosive. It reacts with fat and can cause irreversible damage to any site of contact with the body (for example skin or eyes). Solutions of potassium hydroxide in water at concentrations above 0.5% (w/w) are irritating at points of contact and, at higher concentrations, the solutions can be corrosive. Potassium hydroxide does not cause skin allergies.

Pharmaceutical Applications

Potassium hydroxide (KOH) is widely used in pharmaceutical formulations to adjust the pH of solutions. It can also be used to react with weak acids to form salts.
Therapeutically, potassium hydroxide is used in various dermatological applications.

Pharmacokinetics

The corrosiveness of potassium hydroxide renders it a very useful agent in the decomposition/removal soft tissue and hair removal. It is incorporated into some nail products, shaving creams, and soaps .

Safety

Potassium hydroxide is widely used in the pharmaceutical and food industries and is generally regarded as a nontoxic material at low concentrations. At high concentrations it is a corrosive irritant to the skin, eyes, and mucous membranes.
(rat, oral): 0.273 g/kg

Metabolism

KOH in aqueous solution is entirely dissociated into K+ and OH- ions. Due to the neutralization of OH- by gastric HCl and the quick and efficient blood pH regulation mechanisms (buffer capacity of extra cellular body fluids, respiratory and renal compensation mechanisms), an alkalosis due to the OH- ions after KOH oral dosage in non-irritating conditions is prevented .

The Uses of Potassium hydroxide

Potassium hydroxide (KOH) is also known as caustic potash. It is a strong alkali or a solid base compound that can be used in a variety of industrial applications. It finds its usage in the production of soaps, cleaners and detergents.

Purification Methods

Its carbonate content can be reduced by rinsing potassium hydroxide sticks rapidly with water prior to dissolving them in boiled out distilled water. Alternatively, a slight excess of saturated BaCl2 or Ba(OH)2 can be added to the solution which, after shaking well, is set aside so that the BaCO3 is allowed to separate out.

Incompatibilities

Potassium hydroxide is a strong base and is incompatible with any compound that readily undergoes hydrolysis or oxidation. Violent reaction with acids, alcohols, water, metals (when wet), halogenated hydrocarbons; maleic anhydride. Heat is generated if KOH comes in contact with water and carbon dioxide from the air. It should not be stored in glass or aluminum containers, Corrosive to zinc, aluminum, tin and lead in the presence of moisture releasing combustible/explosive hydrogen gas. Can absorb water from air and give off sufficient heat to ignite surrounding combustible materials.