AUTOMATED IN-VITRO DERMAL ABSORPTION (AIVDA) - A NEW IN-VITRO METHOD FOR INVESTIGATING TRANSDERMAL FLUX

A new in vitro method for investigating transdermal flux is described. The method, called Automated In Vitro Dermal Absorption (AIVDA), empl oyed small autosampler vial inserts (Moody cells) to hold human skin ( 0.07cm(2)) in a standard autosampler carousel. HPLC was used to monito r the permeation rate of test compounds. Analysis was fully automated and remotely monitored and controlled via a modem. A modified Hank's b alanced salt solution was used to minimise HPLC background interferenc e. Permeation assays conducted with Deep Woods(R), a commercial N,N-di ethyl-m-toluamide (DEET)-based mosquito repellent, showed no significa nt difference in DEET absorption between fresh and frozen human abdomi nal skin (Student's t test [p less than or equal to 0.05] 56 +/- 9.1% [n = 4] and 48 +/- 6.3% [n = 4], respectively). No significant differe nce was obtained for DEET absorption in human skin pretreated with bar rier cream. Preliminary tests conducted to validate AIVDA versus the s tandard Bronaugh procedure demonstrated excellent agreement for DEET p ermeation in rat skin (62 +/- 12.8% [n = 4] Moody cells; 59 +/- 8.1% [ n = 3] Bronaugh cells). AIVDA has many advantages over other in vitro permeation tests, including automation, higher analytical sensitivity, rapid sample processing and the ability to use small (5mm outside dia meter) skin specimens.