圈上开攻达线 Factors affecting drug permeation through the skin 国生 Factors affecting drug permeation through the skin Optimal physiochemical properties for transdermal drug ④Formulation factors candidates ·Dosage form ·Dose deliverable <10 mg day-l ·Base ·Molecular weight <500Da ·pH value Lipophilicity (oil-water partition) 10<K<1000 Drug concentration and surface area pH(saturated aqueous solution) pH5-9 Percutaneous penetration enhancer ·Aqueous solubility >1 mg ml! ·Melting point <200°C ·Hydrogen bonding <2 国生 Semisolid dosage forms 国线一 Semisolids are unique systems used for topically application Semisolid dosage forms Semisolid systems retain their shape until acted ·Ointments软膏剂 on by an outside force,whereupon,unlike solids, ·Gels凝胶剂 they are easily deformed. .The rheological properties allow semisolids to be ·Pastes糊剂 spread over the skin to form films that cling ·Rigid foams硬泡沫剂 tenaciously 国生一 Semisolids 国秋生 Gels ④Ointment bases(USP) Gels are semisolid systems in which a liquid ·Oleaginous bases油脂性基质 ·Absorption bases吸收性基质 phase is trapped within an interlocking,three- Those permit the incorporation of aqueous solutions dimensional polymeric matrix. resulting in the formation of W/O emulsions ·W/O emulsions ·Water-removable bases易水洗基质 ·O/W emulsions ·Water-soluble bases水溶性基质 22 Shanghai Jiao Tong University Factors affecting drug permeation through the skin Optimal physiochemical properties for transdermal drug candidates • Dose deliverable <10 mg day-1 • Molecular weight <500 Da • Lipophilicity (oil-water partition) 10<Ko/w <1000 • pH (saturated aqueous solution) pH 5-9 • Aqueous solubility >1 mg ml-1 • Melting point <200°C • Hydrogen bonding <2 Shanghai Jiao Tong University Factors affecting drug permeation through the skin Formulation factors • Dosage form • Base • pH value • Drug concentration and surface area • Percutaneous penetration enhancer Shanghai Jiao Tong University Semisolids are unique systems used for topically application • Semisolid systems retain their shape until acted on by an outside force, whereupon, unlike solids, they are easily deformed. • The rheological properties allow semisolids to be spread over the skin to form films that cling tenaciously. Semisolid dosage forms Shanghai Jiao Tong University Semisolid dosage forms • Ointments 软膏剂 • Gels 凝胶剂 • Pastes 糊剂 • Rigid foams 硬泡沫剂 Shanghai Jiao Tong University Semisolids Ointment bases (USP) • Oleaginous bases 油脂性基质 • Absorption bases 吸收性基质 • Those permit the incorporation of aqueous solutions resulting in the formation of W/O emulsions • W/O emulsions • Water-removable bases 易水洗基质 • O/W emulsions • Water-soluble bases 水溶性基质 Shanghai Jiao Tong University Gels Gels are semisolid systems in which a liquid phase is trapped within an interlocking, three￾dimensional polymeric matrix