ABSTRACT
Dosage forms that are in a plastic, malleable semisolid state at room temperature include ointments, creams, gels, pastes, lotions, jellies, and foams. These semisolid preparations may contain dissolved and/or suspended drugs. Most of the semisolid formulations are used topically to deliver drugs to/through the skin. Ointments are semisolid preparations that incorporate a lipid or hydrophobic excipient and are intended for external application to the skin or other mucosal membranes. Creams are semisolid dosage forms containing one or more drug substances dissolved or dispersed in a suitable oil-in-water or water-in-oil emulsion base. Gels are semisolid systems consisting of dispersions of small or large molecules in an aqueous liquid vehicle, which has been thickened with a gelling agent. Jellies are semisolid gels of intertwining hydrophilic polymers that form a structurally coherent matrix and contain a high proportion of liquid, usually water, hydrogen bonded and associated with the hydrophilic polymer chains.
