An investigation of some factors affecting transdermal permeation.

Al-Saidan, Saleh Mohammed Hamad

Abstract

Factors affecting transdermal permeation were investigated using Differential Thermal Anlaysis (DTA) and in vitro penetration studies of neonatal rat stratum corneum (s.c.), with radiolabelled propanol and hexanol as penetrants. Thermogravimetric Analysis, Thin-Layer Chromatography (TLC) and Infrared Spectroscopy were used to provide additional information. DTA of s.c. revealed four endothermic transitions. Those at 42°, 71° and 80°C were attributed to melting of crystalline lipid, and at 110°C to water loss. TLC indicated that T71 and T80 were related to melting of free fatty acids. The T80 endotherm displaying an irreversibility dependent on both temperature and time of exposure to elevated temperature. This is explained as being due to an interaction between free fatty acids and sterols within s.c. Variations in peak temperature with species and human body site may explain corresponding variations in skin permeability. Both hydration and type of vehicle were found to affect penetration rate. The effect of time and temperature of heat pretreatment (40°-90°C) on s.c. permeability was studied. Large increases in the permeability were obtained above 70°C. This correlates with the irreversible changes in T80 seen with DTA, suggesting distortion of lipid structures. S.C. exposed to DMSO vapour showed lower endothermic temperatures and higher permeability. Heat above 75°C plus DMSO vapour pre-treatments produced similar permeability as heat alone, indicating a common site of action. Studies of the concentration dependance of aqueous DMSO action showed increasing s.c. permeability above 70% DMSO. The corresponding changes in T80 suggested a possible screen test for penetration enhancers which was confirmed with several materials. It is concluded that penetration enhancers appear to disrupt the lipid barrier structures, probably by hydrogen bonding. DTA linked to penetration studies has been shown to be a useful technique for studying the skin barrier and mode of action of penetration enhancers.

Citation

AL-SAIDAN, S.M.H. 1985. An investigation of some factors affecting transdermal permeation. Robert Gordon's Institute of Technology, PhD thesis. Hosted on OpenAIR [online]. Available from: https://doi.org/10.48526/rgu-wt-1993284

• Thesis Type: Thesis
• Deposit Date: Jun 22, 2023
• Publicly Available Date: Jun 22, 2023
• DOI: https://doi.org/10.48526/rgu-wt-1993284
• Keywords: Skin; Skin permeability; Dermal penetration; Transdermal penetration
• Public URL: https://rgu-repository.worktribe.com/output/1993284
• Award Date: May 31, 1985