©上特 - 圈上生 Semisolid dosage forms and transdermal systems Semisolid dosage forms and transdermal systems ·Structure of skin School of pharmacy .Semisolid dosage forms Chen Jian 2013.4 cbenjian.@situ.cdu.cn .Transdermal drug delivery system(patch) 圈生 Structure of skin ©Structure of skin ·Epidermis Stratum corneum/horny layer Viable epidermis .Dermis Network of capillaries Subcutaneous tissue ·Skin appendages 国秋生 国生 ©Stratum corneum Stratum corneum is the principal diffusion barrier for most drugs The outmost layer of skin 62 .The intracellular space of the fully differentiated ·I0-l5 um thickness horny cell is packed full with keratin.Therefore,it is dense and chemically impenetrable. Multilayers,metabolically inactive and flattened Lipid,which is synthesized during a keratinocyte's epidermal transit,becomes a mortar that seals the horny structure. 11 Semisolid dosage forms and transdermal systems School of pharmacy Chen Jian 2013.4 chenjian@sjtu.edu.cn Shanghai Jiao Tong University Semisolid dosage forms and transdermal systems • Structure of skin • Semisolid dosage forms • Transdermal drug delivery system (patch) Structure of skin Shanghai Jiao Tong University Structure of skin • Epidermis • Stratum corneum/horny layer • Viable epidermis • Dermis • Network of capillaries • Subcutaneous tissue • Skin appendages Shanghai Jiao Tong University Stratum corneum • The outmost layer of skin • 10-15 μm thickness • Multilayers, metabolically inactive and flattened Shanghai Jiao Tong University Stratum corneum is the principal diffusion barrier for most drugs • The intracellular space of the fully differentiated horny cell is packed full with keratin. Therefore, it is dense and chemically impenetrable. • Lipid, which is synthesized during a keratinocyte’s epidermal transit, becomes a mortar that seals the horny structure