Polystyrene disks, zeolite

Model II. The Use of Zeolite-Polystyrene Disks as Models in the Study of Drug Penetration through Skin... 

Zeolite-polystyrene disks seem to offer reasonable models for comparison in general, and are mechanically stable and reusable. There seem to be special similarities between zeolite X disks and pigskin dermis and between zeolite Y disks and human dermis. The use of these models is being extended to investigate the use of vehicles in drug transport. These are compounds which increase the rate of drug transport through... 

Figure 5. Self-diffusion rates of l C-salicylic acid through polystyrene-zeolite X disks...

Materials. The zeolites used were X and 2.62 Y. These were compacted in a 13-mm diameter KBr press in the ratio of 3 1 zeolite to emulsion polymer polystyrene by weight. The resulting disk was about 0.35 mm thick. 14C-labeled salicylic acid was supplied by the Radiochemical Center, Amersham. The pigskin used was from the relatively hair-free stomach region of freshly killed pigs, and the human skin was undiseased stomach skin of post-mortem origin. 

To commence measurements, 1 ml of labeled solution was added to one arm (donor), and at the same time an equal volume of unlabeled solution was dispensed to the remaining arm (receptor). Aliquots of 0.1 ml were withdrawn from both arms at suitable time intervals over 4r-5 days. The activity of samples from the receptor side was determined by liquid scintillation counting, and Wt/Wm vs. y/t plots were constructed. The temperature range studied was 20-50°C. (Note salicylic acid was shown not to penetrate disks composed of polystyrene alone, and self-diffusion kinetics were reproducible between different disks of the same polystyrene/zeolite composition). 

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