ABSTRACT
Dosage forms are defined as the systems comprised of one or more active ingredients in association with inert excipients (additives) that constitute the vehicle or formulation matrix. These additives are usually incorporated in the formulation to enhance physical appearance (aesthetic value), facilitate handling, improve stability and potentially influence the absorption and/or bioavailability of the active ingredients. In this context, pharmaceutical semisolid dosage forms including ointment, cream and gels contain one or more medicaments dissolved in or dispersed in a suitable base and appropriate excipients such as emulsifier, gelling agent, viscosity modifiers, antimicrobial agents, antioxidants and or stabilizing agents. These conventional forms of semisolids are meant for delivering drugs into skin and body cavities. But, the recent development in semisolid dosage forms is mainly oriented towards the systemic circulation and more particularly site-specific delivery of drug in an amount, which can elicit therapeutic action. Therefore, this chapter focuses on recent advances in semisolid dosage forms to enhance their aesthetic value and to increase the drug permeation across the skin without impacting their stability, including micro- and nanoemulsion (NE) systems, bioadhesive/mucoadhesive gel, in situ gels (e.g., thermal gel), in situ injectable gels, semisolid containing vesicular systems (e.g., liposomes, ethosomes, niosomes, proniosomes, ethosomesand transfersomes, and 126particulate systems (such as polymeric micro- and nanoparticles, lipid-based particles), cryogels, and pluronic lecithin organogels (PLO). This article also discusses the theory of semisolids, new tools available for the evaluation of semisolids. Furthermore, regulatory requirements for the semisolid dosage forms are also described in this chapter.
