Diethyltoluamide

Most diethyltoluamide (DEET) formulations employ the agent as a liquid to be applied onto human skin in an effort to repel mosquitoes from feeding on the skin. Topical application and absorption is consequently the most common route of absorption. When used appropriately, DEET formulations are generally not indicated for too many other routes of absorption or administration, like parenterally or orally. DEET is absorbed quickly through intact skin; 48% of the applied dose is totally absorbed within 6 hours ^L2775. Topical absorption is the usual route of entry as DEET is normally applied to the skin as a mosquito repellent ^L2775. DEET applied to the skin has also been shown to accumulate in the dermis ^L2775. DEET is rapidly absorbed after oral ingestion ^L2775. Additionally, animal experiments demonstrate that DEET can cross the placenta ^L2775. DEET is efficiently absorbed across the skin and by the gut ^L2779. Blood concentrations of about 3 mg/L have been reported several hours after dermal application in the prescribed fashion ^L2779. Between 9% and 56% of dermally applied DEET is absorbed through the skin with peak blood levels being attained within 1 hour ^L2775. Absorption through the skin varies according to the site exposed to the DEET ^L2775. In animal model surfaces corresponding to the human palmar surface (an area that is typically heavily exposed during the application of liquid DEET), 68% of administered topical DEET was absorbed ^L2775. As a consequence, small children are at increased risk of excessive absorption of DEET applied to the skin because of their relatively higher surface to volume ratio compared to adults ^L2775.