NOVEL DIFFUSION CELL FOR IN-VITRO TRANSDERMAL PERMEATION, COMPATIBLE WITH AUTOMATED DYNAMIC SAMPLING

The development of a new diffusion cell for in vitro transdermal perme ation is described. The so-called Kelder cells were used in combinatio n with the ASPEC system (Automatic Sample Preparation with Extraction Columns), which is designed for the automation of solid-phase extracti ons (SPE). Instead of SPE columns, 20 Kelder cells were placed in the racks. This allowed automatic sampling of up to 20 cells for 24 h in a dynamic mode. The cells consist of an inlet compartment, a donor comp artment and a receptor compartment. The size and the depth of the inle t compartment were important to avoid entrapment of air bubbles in the receptor compartment. The Kelder cells mimic blood flow beneath the s kin by replacement of the permeating drug every 2 min. Hence sink cond itions are more easily maintained than with the static Franz diffusion cell. The performance of the cells was tested with permeation experim ents using atropine as a model drug permeating through an artificial m embrane (Silastic). The use of this skin model minimized the variabili ty in permeation of atropine as compared with human skin.