Lactic Acid

Products

Lactic acid is available as a pure substance in pharmacies and drugstores. It is found in pharmaceuticals, cosmetics, and medical products, including wart remedies, corn remedies, vaginal care products, skin care products, and callus removal products.

Structure and properties

Lactic acid (C3H6O3, Mr = 90.1 g/mol) is an organic acid belonging to the α-hydroxycarboxylic acids. It exists as a colorless to faint yellow syrupy liquid with a typical odor and is miscible with water. In addition to lactic acid, the liquid may also contain condensation products (esters) and water, according to the pharmacopoeia. Lactic acid is a racemate consisting of the – and -enantiomer. The -enantiomer corresponds to L-(+)-lactic acid and is physiological for humans. The -enantiomer is also known as D-(-)-lactic acid. Lactic acid was first isolated from sour milk in the 18th century. It is obtained by bacterial fermentation from sugars such as glucose and lactose, for example with the help of lactobacilli and certain streptococci. This is known as lactic acid fermentation. The salts and esters of lactic acid are called lactates. The pKa (carboxylic acid) is 3.86. Lactic acid is found in higher concentrations in various foods, for example, yogurt, sauerkraut, sour bread, cottage cheese, cheese, sour milk, and some beverages (e.g., Rivella).

Effects

Lactic acid (ATC G01AD01) has corrosive, acidic, keratolytic, and antiseptic properties depending on the concentration of the product. In the vagina, it is involved in maintaining the acidic environment and in immune defense. Furthermore, it plays an important role in metabolism as a metabolite of pyruvate, for example in muscles.

Fields of application

In the form of suitable preparations:

  • Warts, corns, corneal thickening.
  • To strengthen the vaginal environment, vaginal infections.
  • To hydrate the skin in skin care products, in skin diseases.
  • As a pharmaceutical excipient.
  • Lactate in Ringer’s solutions.
  • For chemical syntheses.
  • For the production of active ingredient salts.
  • In beekeeping against varroa mites in honey bees.
  • As a food additive, for example, as a preservative and as an acidifier. Lactic acid fermentation has great importance in the food production of sour milk products and cheese.

Adverse effects

Concentrated (pure) lactic acid is corrosive and may cause skin irritation and severe eye damage if used improperly. The appropriate precautions in the Material Safety Data Sheet must be observed.