Abstract
Microsphere based drug delivery system has gained substantial attention in the modern era. Microspheres are normally free-flowing powders that can be made with both natural and synthetic polymers. The sizes of the microspheres ranges from 1 to 1000 µm. Microspheres are matrix systems in which the drug is uniformly dispersed, dissolved or suspended. Microspheres contain solid or liquid drug dissolved or dispersed in a matrix system. The current review provides an inclusive outline of up to date and novel developments on formations of microspheres which have been reported to increase bioavailability, improves stability, enhances biological half-life and reduces the toxicity of the drug. Microsphere provides efficient delivery of various proteins and peptide molecules. There are different types of microspheres such as bio adhesive microsphere, magnetic microsphere, floating microsphere, and polymeric microspheres. Diverse kinds of methods are used in the formulation of microsphere e. g. Simple emulsion-based method, Double emulsion-based method, Interfacial deposition technique, Interfacial polymerization technique, Phase separation method, and Spray drying. Microspheres deliver the drug in a controlled manner through different routes like oral, topical, naso-pulmonary and gene therapy. The Polymeric based microspheres are model carriers for numerous controlled delivery applications owing to their capacity to encapsulate a diversity of drugs, bio-compatibility, high bio-availability and continuous drug release character. Therefore, by developing newer techniques, it can give more therapeutic effects and improves the safety of drugs. The formation of microspheres has been reported to increase bioavailability, improves stability, enhances biological half-life and reduces the toxicity of the drug.
Highlights
A drug proposed for clinical use must have an optimal therapeutic index
Bhadouriya et al (2014) developed and evaluated a floating drug delivery system containing clopidogrel bisulphate to increase bioavailability and to reduce the side effects caused by the drug like development of drug resistance and gastric bleeding [18, 19]
Alginate Microspheres containing ondansetron prepared by Ionic-gelation method used to sustain the drug release for extended time period though nasal mucosa [60]
Summary
A drug proposed for clinical use must have an optimal therapeutic index (ratio of minimum effective to the maximum safe concentration of drug). The content of magnetic material and the extent of magnetic field applied govern the retention of microspheres at the targeted site [15] These microspheres are kind of gastro retentive systems which prolongs the drug residence time in stomach having size of less than 200 micrometer [16]. Bhadouriya et al (2014) developed and evaluated a floating drug delivery system containing clopidogrel bisulphate to increase bioavailability and to reduce the side effects caused by the drug like development of drug resistance and gastric bleeding [18, 19] These are radiolabeled microspheres used for targeting the drugs to tumors in cancer treatment. Methyl methacrylate (PMMA), Glycidyl methacrylate, Epoxy polymers, Acrolein) [28]
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