The isolated rabbit ear was perfused by an erythrozyte- containing blood- equivalent medium circulating in a closed circuit. The presented model enables dermal resorption studies with low technical expense. The experimental conditions were as far as possible standardized and adapted to physiological circumstances. Proved by biochemical and histoloical examinations the isolated rabbit ear is viable over a period of 2 hours. Glukose utilization, LDH and potassium leakage into the perfusate were

more »

... asured. The interpretation of these parameters and the comparison with the results of other scientists did not refer to cell or membrane damages. Within the microscopical examinations the density of hair was found out as a factor influencing the permeability. At the area of application about 950 hair follicles/ cm2 were counted and at the margin of the ear are situated 1240 hairs/ cm2 on an avarage. One primary hair and 3- 5 wool hairs are clustered. Sebeceous glands are close to the hair groups. There are no sweat glands at the rabbit ear. Testing the model, the percutaneous absorption of an oily testosterone solution containing testosteronenantate and castor oil was ascertained. One milliliter of the test substance includes 250 mg Testosteronenantate. In the beginning of the perfusion 2500 µg/ cm2 of skin were applied to an area of 20 cm2 of the convexe side of the rabbit ear. After two hours 0,0288 % of applied dose were determined in the perfusate. Comparing the present results with the examinations by other authors parallels at resorption behaviour are pointed out. By reason of different experimental conditions there are several restrictions.