Polymeric micelles for oral drug delivery: Why and how

Abstract

Abstract:The oral delivery of drugs is regarded as the optimal means for achieving therapeutic effects owing to increased patient compliance. Unfortunately, the oral delivery route is beset with problems such as gastrointestinal (GI) destruction of labile molecules, low levels of macromolecular absorption, etc. To reduce the impact of digestive enzymes and to ensure the absorption of bioactive agents in an unaltered form, molecules may be incorporated into microparticulate carriers. Many approaches to achieve the oral absorption of a wide variety of drugs are currently under investigation. Among the different polymer-based drug delivery systems, polymeric micelles represent a promising delivery vehicle especially intended for poorly water-soluble pharmaceutical active ingredients in order to improve their oral bioavailability. Recent findings of a dextran-based polymeric micelle study for solubilization of a highly lipophilic drug, cyclosporin A (CsA), will be discussed.

Conventional Synthesis of Amphiphilic Block Copolymer Utilized for Polymeric Micelle by Mechanochemical Solid-State Polymerization

“…[29][30][31][32][33][34] When a unitary solvent, such as water, is used as a selective solvent to form star micelles, spherical micelles are obtained and other micellar shapes not formed within our knowledge. [1][2][3][4][5][6][7][8][9][10]31,32,[35][36][37][38] The PMG-Te possessed much longer hydrophilic blocks than hydrophobic blocks. Therefore, a spherical micelle would be formed by the aggregation of PMG-Te.…”

“…Such micelles have attracted much attention in drug delivery systems because of their ability to solubilize hydrophobic molecules; nanoscale size; good thermodynamic solution stability; extended release of various drugs; and prevention of rapid clearance by the reticuloendothelial system. [1][2][3][4][5][6][7][8][9][10] One needs to use model polymers with well-controlled molecular weight, narrow molecular weight distribution, and low compositional heterogeneity for systematic studies of micellar properties. Living polymerization is eminently suitable to prepare block copolymers with these properties.…”

Preliminary spectroscopic characterization of PEGylated mucin, a novel polymeric drug delivery system

“…Oral administration of therapeutic agents represents by far the easiest, safest and most convenient route of drug delivery, especially in the case of chronic therapies (Kreuter, 1991). Unfortunately, the oral delivery route is beset with problems such as gastrointestinal (GI) destruction of labile molecules and low levels of macromolecular absorption (Francis et al, 2004). The development of oral forms of many drugs however remains a challenge either on account of their stability or their absorption from the GIT thus leading to sub-therapeutic bioavailability (Kreuter, 1991).…”

Novel pH-Responsive Polymeric Micelles Prepared through Self-assembly of Amphiphilic Block Copolymer with Poly-4-vinylpyridine Block Synthesized by Mechanochemical Solid-State Polymerization

“…Considerable attention has been paid to the use of polymeric micelles in drug delivery systems because of their ability to solubilize hydrophobic molecules and their nanoscale size, good thermodynamic stability in solution, capacity for extended release of various drugs, and their resistance to rapid clearance by the reticuloendothelial system. [1][2][3][4][5][6][7][8][9] Stimulus-responsive polymeric micelles have recently emerged as a novel controlled-release system in which drugs can be released by applying an appropriate stimulus, such as a specific temperature, pH, or ultrasound. A pHsensitive polymeric micelle would be particularly useful for targeting tumor tissues, endosomes, and lysosomes because these sites are more acidic than other parts of the body, such as the blood.…”