ABSTRACT
Liquid formulations offer many advantages, from ease in dosing to ease in administration (easy to swallow), and myriad possibilities of innovative drug delivery systems. One of the most desirable features of liquid formulations, particularly the solution forms, is the relatively lower importance of bioavailability considerations, as the drug molecules are already in the dispersed phase, removing many rate-limiting steps in the absorption of drugs. For the purpose of this volume, liquid formulations include formulations that have liquid characteristics, meaning they can flow and thus include clear liquids, suspensions, and extemporaneous powder suspensions (which could easily be classified as uncompressed solids but for the stability considerations postreconstitution, which are common to liquid preparations). However, all of the advantages of liquid dosage forms are balanced by the many problems in their formulation. These include stability problems, taste masking needs, phase separations, and so forth, all of which require highly specialized formulation techniques.
