Pharmaceutical Applications of colloids:
Colloids are extensively used for modifying the properties of pharmaceutical agents. The most common property that is affected is the solubility of a drug .However, colloidal forms of many drugs exhibits substantially different properties when compared with traditional forms of these drugs. Certain medicinals have been found to possess unusual or increased therapeutic properties when formulated in the colloidal state. Another important pharmaceutical application of colloid is their use as drug delivery system. The most often used colloid type drug delivery systems include hydrogels, microspheres, microemulsions, liposomes, micelles, nanoparticles and nanocrystals. Here we mention the main characteristics of each colloidal delivery system.
Hydrogel is a colloidal gel in which water is the dispersion medium. It (also called aquagel) is a network of polymer chains that are hydrophilic, sometimes found as a colloidal gel in which water is the dispersion medium. Hydrogels are highly absorbent (they can contain over 99% water) natural or synthetic polymers. Hydrogels also possess a degree of flexibility very similar to natural tissue, due to their significant water content. These hydrogels have the ability to sense changes of pH, temperature, or the concentration of metabolite and release their load as result of such a change Natural and synthetic hydrogels are used for wound healing, as scaffolds in tissue engineering, and as sustained- release delivery systems. When used as scaffolds for tissue engineering, hydrogels may contain human cells to stimulate tissue repair, since they are loaded with pharmaceutical ingredients, hydrogels provide a sustained drug release. Light-sensitive, pressure- responsive, and electro-sensitive hydrogels also have the potential to be used in drug delivery. Environmentally sensitive hydrogels include slow response time, limited biocompatibility, and biodegradability. Hydrogel used as sustained-release drug delivery systems. it provide absorption, desloughing and debriding capacities of necrotics and fibrotic tissue.hydrogels that are responsive to specific molecules, such as glucose or antigens can be used as biosensors, as well as in DDS.Also used in disposable diapers where they "capture" urine, or in sanitary napkins, contact lenses (silicone hydrogels, polyacrylamides).Medical electrodes using hydrogels composed of cross-linked polymers (polyethylene oxide, polyAMPS and polyvinylpyrrolidone).hydrogel used as water gel explosives, rectal drug delivery and diagnosis. Other, less common uses include, breast implants, granules for holding soil moisture in arid areas, dressings for healing of burn or other hard-to-heal wounds. Wound gels are excellent for helping to create or maintain a moist environment, reservoirs in topical drug delivery; particularly ionic drugs, delivered by iontophoresis (see ion exchange resin), Common ingredients are e.g. polyvinyl alcohol, sodium polyacrylate, acrylate polymers and copolymers with an abundance of hydrophilic groups. Natural hydrogel materials are being investigated for tissue engineering; these materials include agarose, methylcellulose, hyaluronan, and other naturally derived polymers. .However if the achievements of the past can be extrapolated into the future, it is likely that responsive hydrogels with a wide array of desirable properties will be forthcoming.
Microparticles are small loaded microspheres of natural or synthetic polymers.Microparticles was initially developed as carriers for vaccines and anti-cancer drugs. More recently, novel properties of Microparticles have been developed to increase the efficiency of drug delivery and improve release profiles and drug targeting. Several investigations have focused on the development of methods of reducing the uptake of the nanoparticles by the cells of the...