Mequinol

Mequinol, MeHQ or 4-methoxyphenol, is a phenol used in dermatology and organic chemistry. Mequinol, MeHQ or 4-methoxyphenol, is a phenol used in dermatology and organic chemistry. Mequinol is a common active ingredient in topical drugs used for skin depigmentation. As a topical drug mequinol is often mixed with tretinoin, a topical retinoid. A common formulation for this drug is an ethanolic solution of 2% mequinol and 0.01% tretinoin by mass. Dermatologists commonly prescribe the drug to treat solar lentigines, liver spots, or age spots. Lower dosages of mequinol have been used in conjunction with a Q-switched laser to depigment skin in patients with disseminated idiopathic vitiligo. In organic chemistry 4-methoxyphenol is used to inhibit the radical polymerization of monomers (e.g. acrylates or styrene monomers). 4-Methoxyphenol is produced from p-benzoquinone and methanol via a free radical reaction. People can be exposed to 4-methoxyphenol in the workplace by breathing it in, skin absorption, swallowing it, skin contact, and eye contact. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) of 5 mg/m3 over an 8-hour workday.