title: Relationship between Surface Properties and In Vitro Drug Release from Compressed Matrix Containing Polymeric Materials with Different Hydrophobicity Degrees.
abstract: This work is the continuation of a study focused on establishing relations between surface thermodynamic properties and in vitro release mechanisms using a model drug (ampicillin trihydrate), besides analyzing the granulometric properties of new polymeric materials and thus establishing the potential to be used in the pharmaceutical field as modified delivery excipients. To do this, we used copolymeric materials derived from maleic anhydride with decreasing polarity corresponding to poly(isobutylene-alt-maleic acid) (hydrophilic), sodium salt of poly(maleic acid-alt-octadecene) (amphiphilic), poly(maleic anhydride-alt-octadecene) (hydrophobic) and the reference polymer hydroxyl-propyl-methyl-cellulose (HPMC). Each material alone and in blends underwent spectroscopic characterization by FTIR, thermal characterization by DSC and granulometric characterization using flow and compaction tests. Each tablet was prepared at different polymer ratios of 0%, 10%, 20%, 30% and 40%, and the surface properties were determined, including the roughness by micro-visualization, contact angle and water absorption rate by the sessile drop method and obtaining Wadhand surface free energy (SFE) using the semi-empirical models of Young-Dupré and  Owens-Wendt-Rabel-Käelbe (OWRK), respectively. Dissolution profiles were determined simulating physiological conditions in vitro, where the kinetic models of order-zero, order-one, Higuchi and Korsmeyer-Peppas were evaluated. The results showed a strong relationship between the proportion and nature of the polymer to the surface thermodynamic properties and kinetic release mechanism.
authors.affiliation: Pharmaceutical Physical Chemistry Laboratory, Natura Research Group, Pharmaceutical Chemistry Program, Faculty of Natural Sciences, ICESI University, Cali 760031, Colombia. cjyarce@icesi.edu.co.
authors.forename: Cristhian J
authors.initials: CJ
authors.lastname: Yarce
authors.affiliation: Pharmaceutical Physical Chemistry Laboratory, Natura Research Group, Pharmaceutical Chemistry Program, Faculty of Natural Sciences, ICESI University, Cali 760031, Colombia. juandiegoqf@hotmail.com.
authors.forename: Juan D
authors.initials: JD
authors.lastname: Echeverri
authors.affiliation: Pharmaceutical Physical Chemistry Laboratory, Natura Research Group, Pharmaceutical Chemistry Program, Faculty of Natural Sciences, ICESI University, Cali 760031, Colombia. marioandres_8@hotmail.com.
authors.forename: Mario A
authors.initials: MA
authors.lastname: Palacio
authors.affiliation: Pharmaceutical Physical Chemistry Laboratory, Natura Research Group, Pharmaceutical Chemistry Program, Faculty of Natural Sciences, ICESI University, Cali 760031, Colombia. carlosrive114@gmail.com.
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Rivera
authors.affiliation: Pharmaceutical Physical Chemistry Laboratory, Natura Research Group, Pharmaceutical Chemistry Program, Faculty of Natural Sciences, ICESI University, Cali 760031, Colombia. chsalamanca@icesi.edu.co.
authors.forename: Constain H
authors.initials: CH
authors.lastname: Salamanca
keywords: ampicillin trihydrate; contact angle; drug release; polymeric materials; surface free energy