Advances in semisolid dosage form

The semisolid dosage form is considered one of the major routes of administration. Semisolid dosage forms are also known as topical application dosage forms as they are meant to be applied on the skin. The absorption of these drugs is possible as they penetrate through the layers of the skin. Drugs with a molecular weight of less than 600 Da and high diffusion and permeation constants are considered good choices for topical dosage forms. Mostly, they are meant to have localized therapeutic actions, but with the recent advancements in transdermal patches, they have also been reported to have systemic drug effects. The most common semisolid dosage forms are creams, gels, ointments, and pastes. The drugs are dispersed in the base or vehicles either by the trituration or the fusion method. Various bases classified as oleaginous, absorption, water-soluble, and emulsifying are used for the formulation of semisolid dosage forms. Stabilizers such as emulsifying agents, so-solvents, thickening agents, humectants, antioxidants, and preservatives are also added to improve the stability of the dosage forms. The chapter also includes a description of the quality control methods, such as rheology, gel strength, and in vitro drug release. Finally, various uses of microspheres, liposomes, and nanoparticles in semisolid topical dosage forms have also been discussed. The chapter serves as a good source of information on solid dosage forms for undergraduate and postgraduate students