title: Advances in oral controlled drug delivery: the role of drug-polymer and interpolymer non-covalent interactions.
abstract: BACKGROUND
  After more than four decades of intense research, oral controlled drug delivery systems (DDSs) still represent a topic of major interest for pharmaceutical scientist and formulators. This can be explained in part by considering the economic value of oral DDSs whose market accounts for more than half of the overall drug delivery market. Polymeric systems based on drug-polymer non-covalent interaction represent a limited, but growing part of the field. Despite the large amount of literature and published reviews covering specific aspects, there is still need for a review of the relevant literature providing a general picture of the topic.
  
  
  METHODS
  The present review aims at presenting the latest findings in drug-polymer and interpolymer non-covalent interactions in oral controlled delivery while providing a specific perspective and a critical point of view, particularly on the tools and methods used for the study of these DDSs. Four main sections are considered: i) ionic interactions between drugs and polymers; ii) interpolymer complexes; iii) hydrogen bond; and iv) hydrophobic interactions.
  
  
  CONCLUSIONS
  The largest part of the scientific literature deals with systems based on drug-polymer ionic interactions while hydrogen bonding and hydrophobic interaction though, very promising, are more difficult to exploit, and therefore less studied. An accurate and exhaustive representation of the specific role of the chemical functions in establishing predictable interactions between drug and polymers is still required.
authors.affiliation: PhD Student, University of Parma, Department of Pharmacy , Parma , Italy.
authors.forename: Simona
authors.initials: S
authors.lastname: De Robertis
authors.forename: Maria Cristina
authors.initials: MC
authors.lastname: Bonferoni
authors.forename: Lisa
authors.initials: L
authors.lastname: Elviri
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Sandri
authors.forename: Carla
authors.initials: C
authors.lastname: Caramella
authors.forename: Ruggero
authors.initials: R
authors.lastname: Bettini
mesh_terms: D000284:Administration, Oral; D002626:Chemistry, Pharmaceutical / Q000379:methods*; D003692:Delayed-Action Preparations / Q000737:chemistry*; D016503:Drug Delivery Systems / Q000379:methods*; D065546:Drug Liberation; D005079:Excipients / Q000737:chemistry*; D006860:Hydrogen Bonding; D007477:Ions / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*
chemical_list: D003692:Delayed-Action Preparations; D005079:Excipients; D007477:Ions; D011108:Polymers
keywords: Eudragit; alginate; carrageenan; chitosan; controlled release; drug–polymer interaction; interpolymer complex; oral delivery; polyelectrolyte complex