国人生 国生 Semisolids are unique systems used for topically application Semisolid dosage forms Semisolid systems retain their shape until acted .Ointments on by an outside force,whereupon,unlike solids, ·Gels they are easily deformed. .The rheological properties allow semisolids to be ·Pastes spread over the skin to form films that cling ·Rigid foams tenaciously. 国生一 图上生 Semisolid dosage forms Semisolid dosage forms ·Ointment bases(USP) ·Ointment bases(USP) ·Oleaginous bases Oleaginous bases(hydrocarbon bases) ·Absorption bases -Hydrocarbon-based semisolids containing -W/O emulsions dissolved or suspended drugs. .Water-removable bases -Can be made by incorporating high-melting -O/W emulsions waxes into fluid mineral oil at high Water-soluble bases temperature. 国丝生 国生 Semisolid dosage forms Semisolid dosage forms ·Ointment bases(USP) ·Ointment bases(USP) Oleaginous bases(hydrocarbon bases) ·Absorption bases -Effective as occlusive dressings -permit the incorporation of aqueous -Have an emollient effect solutions resulting in the formation of W/O -Remain on the skin for long periods emulsions -Difficult to wash off -limited by the relative insolubility of drug 33 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. Shanghai Jiao Tong University Semisolid dosage forms • Ointments • Gels • Pastes • Rigid foams Shanghai Jiao Tong University Semisolid dosage forms • Ointment bases (USP) • Oleaginous bases • Absorption bases – W/O emulsions • Water-removable bases – O/W emulsions • Water-soluble bases Shanghai Jiao Tong University Semisolid dosage forms • Ointment bases (USP) • Oleaginous bases (hydrocarbon bases) – Hydrocarbon-based semisolids containing dissolved or suspended drugs. – Can be made by incorporating high-melting waxes into fluid mineral oil at high temperature. Shanghai Jiao Tong University Semisolid dosage forms • Ointment bases (USP) • Oleaginous bases (hydrocarbon bases) – Effective as occlusive dressings – Have an emollient effect – Remain on the skin for long periods – Difficult to wash off – limited by the relative insolubility of drug Shanghai Jiao Tong University Semisolid dosage forms • Ointment bases (USP) • Absorption bases – permit the incorporation of aqueous solutions resulting in the formation of W/O emulsions