title: Polymeric micelles for oral drug administration enabling locoregional and systemic treatments.
abstract: BACKGROUND
  Amphiphilic block copolymers are recognized components of parenteral drug nanocarriers. However, their performance in oral administration has barely been evaluated to any great extent.
  
  
  METHODS
  This review provides an overview of the methods used to prepare drug-loaded polymeric micelles and to evaluate their stability in gastrointestinal (GI) fluids, and then analyzes in detail recent in vitro and in vivo results about their performance in oral drug delivery. Oral administration of polymeric micelles has been tested for a variety of therapeutic purposes, namely, to increase apparent drug solubility in the GI fluids and facilitate absorption, to penetrate in pathological regions of the GI tract for locoregional treatment, to carry the drug directly toward the blood stream minimizing presystemic loses, and to target the drug after oral absorption to specific tissue or cells in the body.
  
  
  CONCLUSIONS
  Each therapeutic purpose demands micelles with different performance regarding stability in the GI tract, ability to overcome physiological barriers and drug release patterns. Depending on the block copolymer composition and structure, a wealth of self-assembled micelles with different morphologies and stability can be prepared. Moreover, copolymer unimers can play a role in improving drug absorption through the GI mucosa, either by increasing membrane permeability to the drug and/or the carrier or by inhibiting drug efflux transporters or first-pass metabolism. Therefore, polymeric micelles can be pointed out as versatile vehicles to increase oral bioavailability of drugs that exhibit poor solubility or permeability and may even be an alternative to parenteral carriers when targeting is pursued.
authors.affiliation: University of Coimbra, Faculty of Pharmacy , Coimbra , Portugal +351 239 855099 ; fveiga@ci.uc.pt.
authors.forename: Susana M N
authors.initials: SM
authors.lastname: Simões
authors.forename: Ana R
authors.initials: AR
authors.lastname: Figueiras
authors.forename: Francisco
authors.initials: F
authors.lastname: Veiga
authors.forename: Angel
authors.initials: A
authors.lastname: Concheiro
authors.forename: Carmen
authors.initials: C
authors.lastname: Alvarez-Lorenzo
mesh_terms: D000284:Administration, Oral; D000818:Animals; D001682:Biological Availability; D016503:Drug Delivery Systems; D006801:Humans; D008823:Micelles; D010539:Permeability; D004364:Pharmaceutical Preparations / Q000008:administration & dosage* / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*; D012995:Solubility
chemical_list: D008823:Micelles; D004364:Pharmaceutical Preparations; D011108:Polymers
keywords: drug solubilization; efflux inhibition; locoregional treatment; micelle architecture; oral administration; polymeric micelles