Microencapsulation has been applied to solve problems in the development of pharmaceutical dosage forms as well as in cosmetics for several purposes. These include the conversion of liquids to solids, separation of incompatible components in dosage form, taste masking, reduction of gastrointestinal irritation, protection of the core materials against atmospheric deterioration, and enhancement of stability and controlled-release of active ingredients.
For drug follicular targeting, microspheres were envisaged mainly as site-specific drug delivery systems because they present several advantages: 1) good stability of the microspheres when applied on the skin, 2) easy preparation of microspheres with a defined size in a narrow size distribution, 3) protection of the active incorporated, 4) controlled release of the active in the hair follicles from the microspheres, and 5) the possibility of incorporating either lipophilic or hydrophilic actives into the microspheres . Concerning the microsponge system, each microsphere is composed of thousands of small beads wrapped together to form a microscopic sphere capable of binding, suspending, or entrapping a range of substances. The outer surface is porous, allowing the controlled flow. Microsponges can be incorporated into gels, creams, liquids, powders, or other formulations, and can release ingredients depending on their temperature, moisture, friction, volatility of the entrapped ingredient, or time.
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