Zinc pyrithione


Zinc pyrithione is a coordination complex of zinc. It has fungistatic and bacteriostatic properties and is used in the treatment of seborrhoeic dermatitis.

Structure of the compound

The pyrithione ligands, which are formally monoanions, are chelated to Zn2+ via oxygen and sulfur centers. In the crystalline state, zinc pyrithione exists as a centrosymmetric dimer, where each zinc is bonded to two sulfur and three oxygen centers. In solution, however, the dimers dissociate via scission of one Zn-O bond.
This compound was first described in the 1930s.
Pyrithione is the conjugate base derived from 2-mercaptopyridine-N-oxide, a derivative of pyridine-N-oxide.

Uses

Medical

Zinc pyrithione is best known for its use in treating dandruff and seborrhoeic dermatitis, particularly in dandruff shampoos. It also has antibacterial properties and is effective against many pathogens from the Streptococcus and Staphylococcus genera. Its other medical applications include treatments of psoriasis, eczema, ringworm, fungus, athletes foot, dry skin, atopic dermatitis, tinea, and vitiligo.

In paint

Due to its low solubility in water, zinc pyrithione is suitable for use in outdoor paints and other products that provide protection against mildew and algae. It is an effective algaecide. It is chemically incompatible with paints relying on metal carboxylate curing agents. When used in latex paints with water containing high amount of iron, a sequestering agent that will preferentially bind the iron ions is needed. Its decomposition by ultraviolet light is slow, providing years of protection even against direct sunlight.

In sponges

Zinc pyrithione is also used as an antibacterial treatment for household sponges, most notably by the 3M Corporation.

In clothing

A process to apply zinc pyrithione to cotton with washable results was patented in the United States in 1984. Zinc pyrithione is now used to prevent microbe growth in polyester. Textiles with applied zinc pyrithione protect against odor-causing microorganisms. Export of antimicrobial textiles reached US$497.4 million in 2015.

Mechanism of action

Its antifungal effect is thought to derive from its ability to disrupt membrane transport by blocking the proton pump that energizes the transport mechanism.

Health effects

Zinc pyrithione is approved for over-the-counter topical use in the United States as a treatment for dandruff and is the active ingredient in several antidandruff shampoos. In its industrial forms and strengths, it may be harmful by contact or ingestion. Zinc pyrithione can trigger a variety of responses, such as DNA damage in skin cells.