[Percutaneous absorption of nonsteroidal anti-inflammatory preparations].

Percutaneous uptake of anti-inflammatory drugs is very small. The velocity of permeation for all substances may be described by permeation constants over a long time after deposition in the lipid phase of the horny layer, and an analogous function of the infusion kinetics may be generally used. Examples of salicylic acid and methyl salicylate applied by bathing and of indomethacine were discussed. Plasma values were used to compare different application methods. They rise to 10 ng/ml salicylic acid and 450 ng/ml metabolized methyl salicylate during first hour and 20 minutes bathing the whole body. After the first hour plasma levels by use of salicylic acid are nearly constant and by use of methyl salicylate decrease quickly. These values are in good agreement with calculated values by a kinetic model. Another application method for NSAIDs is the iontophoresis. By this method higher permeation rates are generally found. Iontophoresis of salicylic acid on 400 cm2 of the skin daily resulted in plasma values going up to about 600 ng/ml. By use of this method for the uptake of indomethacine on 1380 cm2 of the skin for one hour plasma values going up to 100-350 ng/ml were attained. Tissue concentration of salicylic acid in the epidermis is about one hundredth of the concentration of the applied solution. By iontophoresis using 0.1 mA/cm2 the concentration in the epidermis increases about ten times. The concentration in the dermis is higher than the plasma levels but in other tissues no differences regarding the plasma levels were found.(ABSTRACT TRUNCATED AT 250 WORDS)