PERCUTANEOUS-ABSORPTION OF DODECYLTRIMETHYLAMMONIUM BROMIDE, A CATIONIC SURFACTANT, IN THE RAT

The route and rate of excretion of the cationic surfactant [14C]dodecyl-trimethylammonium bromide (DTB) given by parenteral injection were investigated in rats, and the percutaneous absorption of the surfactant through non-occluded rat skin and the resulting blood levels were also studied. The surfactant was applied to the intact clipped skin of rats in aqueous solution or in a hair-rinse formulation. Elimination by the rat after parenteral administration was rapid and was effected primarily via the urine, more than 80% of the radioactivity being eliminated within 24 hr of application. Percutaneous absorption of the surfactant was low. Application in a cream hair-rinse preparation under user conditions resulted in the absorption of about 0·1% of the administered radioactivity in 48 hr. No measurable radioactivity was present in the blood. Application of the surfactant at a higher concentration in aqueous solution gave a somewhat higher absorption (0·6% in 72 hr). Some radioactivity (equivalent to less than 100 ng unchanged DTB/g) was found in the blood after application of the surfactant to the skin without subsequent rinsing. © 1979.