INSECT REPELLANT INTERACTIONS: SUNSCREENS ENHANCE DEET (N,N-DIETHYL-M-TOLUAMIDE) ABSORPTION

• Published in: Drug metabolism and disposition Vol. 32; no. 8; pp. 783 - 785
• Main Authors: ROSS, Edward A, SAVAGE, Kathleen A, UTLEY, Luke J, TEBBETT, Ian R
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Pharmacology and Experimental Therapeutics 01.08.2004
• Subjects: Biological and medical sciences; Diseases of the skin. Cosmetics; Domestic and cosmetic products toxicology; Medical sciences; Radiotherapy. Instrumental treatment. Physiotherapy. Reeducation. Rehabilitation, orthophony, crenotherapy. Diet therapy and various other treatments (general aspects); Toxicology; Diethyltoluamide; Toxicokinetics; Vertebrata; Mammalia; Absorption; Poison interaction; Mouse; Animal; Rodentia; Repellent; Sunscreen product; Topical administration
• ISSN: 0090-9556; 1521-009X
• DOI: 10.1124/dmd.32.8.783

Toxicology studies are typically performed on single compounds, which we hypothesized would miss adverse synergies from chemical mixtures. This hypothesis was tested using an insect repellant and sunscreens because both groups include known permeation enhancers, with prior pediatric reports of toxicity from highly concentrated DEET ( N , N -diethyl- m -toluamide). Using real-time mass spectroscopy in a hairless mouse skin model, we confirmed substantial penetration of a 20% DEET standard. Despite a lower (10%) DEET content, a commercially marketed sunscreen formulation had a 6-fold more rapid detection (5 versus 30 min) and 3.4-fold greater penetration at steady state. We also tested the efficacy of DEET microemulsion products and confirmed that one successfully slowed the onset of absorption, but not the steady-state permeation. Risks from mixtures of potential toxins are worthy of routine testing, which can be accomplished by simple assays, and are of utmost importance for pediatric applications.