Dimethyl sulfoxide (DMSO) as a solvent in acute toxicity determinations

3 Final Report on the Safety Assessment of Benzethonium Chloride and Methylbenzethonium Chloride

Benzethonium Chloride and Methylbenzethonium Chloride are quaternary ammonium salts used in cosmetics primarily as preservatives and secondarily as cationic surfactants, usually at concentrations below 1 percent. They can be irritating to the skin at concentrations of greater than 5 percent. Chronic and subchronic feeding studies indicated little or no toxic effects for both ingredients. Benzethonium Chloride was nonmutagenic in microbial systems and shown to be noncarcinogenic in rodent studies.

In clinical studies, Benzethonium Chloride produced mild skin irritation at 5 percent but not at lower concentration. Neither ingredient is considered to be a sensitizer.

It is concluded that both compounds are safe at concentrations of 0.5 percent in cosmetics applied to the skin. A maximum concentration of 0.02 percent is safe for cosmetics used in the eye area.

Pharmacologic and biochemical considerations of dimethyl sulfoxide

DMSO has multiple known pharmacological properties. In addition to those referred to include: cryoprotective action, radioprotective effect, influence on serum cholesterol in experimental hypercholesteremia, and platelet aggregation antagonism. How the multiple properties of this chemical affect therapy in clinical medicine must yet be explained. It is clear, however, that DMSO does affect biological systems, and that this influence has many clinical applications. Perhaps one of the most interesting and significant properties of DMSO is its ability to move other drugsthrough membranes. When mixed with DMSO, many drugs appear to be potentiated in their physiologic effect; thus smaller doses are required and less toxicity is demonstrated. In cancer chemotherapy, this value already has practical use. Some of the studies to be reported in this monograph will describe additional, almost unbelievable observations. Perhaps the mechanism of action of these clinical phenomena will be found in one or more of the pharmacological properties described. It would not be surprising, however, if we were to conclude with a resolution to search for new explantations of the mystery of DMSO, for it would appear that DMSO is really a new principle in medicine and cannot always be measured by existing standards.

Dimethyl sulfoxide: interactions with aromatic hydrocarbons

Dimethyl sulfoxide (DMSO) enhanced the hypertaurinuria produced by benzene, chlorobenzene, and toluene in rats. Undiluted DMSO was more effective than DMSO diluted with water in potentiating the toxicity of benzene in both rats and mice. Supernatants (9000g) prepared from livers of rats treated with DMSO 24 hours earlier metabolized more benzene than those from control rats.