Thymol

Synonyms: Acido trimico; 3-p-cymenol; p-cymen-3-ol; Flavinol; 3-hydroxy-pcymene; 3-hydroxy-1-methyl-4-isopropylbenzene; Intrasol; isopropyl cresol; isopropyl-m-cresol; 6-isopropyl-m-cresol; isopropyl
metacresol; 2-isopropyl-5-methylphenol; 1-methyl-3-hydroxy-4-
isopropylbenzene; 5-methyl-2-isopropylphenol; 5-methyl-2-(1-
methylethyl) phenol; Medophyll; thyme camphor; thymic acid; mthymol; thymolum; timol.

Description: Thymol occurs as colorless or often large translucent crystals, or as a white crystalline powder with a herbal odor (aromatic and thymelike) and a pungent caustic taste.

Chemical Name: Thymol

Antioxidant; antiseptic; cooling agent; disinfectant; flavoring agent; skin penetrant; therapeutic agent.

• Thymol is a phenolic antiseptic, which has antibacterial and antifungal activity.

• However, it is not suitable for use as a preservative in pharmaceutical formulations because of its low aqueous solubility.

• The antimicrobial activity of thymol against eight oral bacteria has been studied in vitro.

• Inhibitory activity was noted against almost all organisms, and a synergistic effect was observed for combinations of thymol and eugenol, and of thymol and carvacrol.

• The activity of thymol against bacteria commonly involved in upper respiratory tract infections has also been shown.

• Thymol is a more powerful disinfectant than phenol, but its low water solubility, its irritancy to tissues, and its inactivation by organic material, such as proteins, limit its use as a disinfectant.

• Thymol is chiefly used as a deodorant in antiseptic mouthwashes, gargles, and toothpastes, such as in Compound Thymol Glycerin BP, in which it has no antiseptic action.

• Thymol is also a true antioxidant and has been used at concentrations of 0.01% as an antioxidant for halothane, trichloroethylene, and tetrachloroethylene.

• The antioxidant activity of thymol and thymol analogues has been described.

• More recently, thymol has been shown to enhance the in vitro percutaneous absorption of a number of drugs, including 5- fluorouracil, piroxicam, propranolol, naproxen, and tamoxifen.

• Studies have also demonstrated that the melting point of lidocaine is significantly lowered when it is mixed with thymol

Thymol is incompatible with iodine, alkalis, and oxidizing agents. It liquefies, or forms soft masses, on trituration with acetanilide, antipyrine, camphor, monobromated camphor, chloral hydrate, menthol, phenol, or quinine sulfate. The antimicrobial activity of thymol is reduced in the presence of proteins.

Thymol is used in cosmetics, foods, and pharmaceutical applications as an excipient. However, thymol may be irritating when inhaled or following contact with the skin or eyes. It may also cause abdominal pain and vomiting, and sometimes stimulation followed by depression of the central nervous system following oral consumption; fats and alcohol increase absorption and aggravate symptoms.

Observe normal precautions appropriate to the circumstances and quantity of material handled. Special precautions should be taken to avoid inhalation, or contact with the skin or eyes. Eye protection and gloves are recommended. When thymol is heated to decomposition, carbon dioxide and carbon monoxide are formed.

Menthol.