title: Drug release from complexes with a series of poly(carboxyalkyl methacrylates), a new class of weak polyelectrolytes.
abstract: Carboxyalkyl methacrylates, a new class of non-cross-linked, hydrophobic weak polyelectrolytes, were synthesized, and then bound to cationic drugs (propranolol.HCl, diltiazem.HCl and verapamil.HCl) to form water-insoluble complexes that release the bound drug only in ionic media (pH 7.4). Compressed tablets were prepared from these cation exchange polyelectrolytes. Release profiles followed zero order kinetics (n>0.90; n is the release exponent). As the hydrophobicity of the polyelectrolytes increased, the rate of release decreased and deviated from linearity (n=0.7). Both the ionic strength of the medium as well as the solubility of the drug affected the rate of release. In acidic media (pH 1.2) a burst of drug was released but the release was halted by a layer of non-ionized polymer precipitated on the surface of the tablets. The results indicate that it is possible to "tailor-make" the release kinetics by using a polyelectrolyte from the series with the suitable hydrophobicity.
authors.affiliation: Facultad de Ciencias Químicas e Ingeniería, Universidad Autónoma de Baja California, PMB 121, 2498 Roll Dr, San Diego, CA 92154, USA. jmcornejo@uabc.mx
authors.forename: Jose M
authors.initials: JM
authors.lastname: Cornejo-Bravo
authors.forename: Maria E
authors.initials: ME
authors.lastname: Flores-Guillen
authors.forename: Eder
authors.initials: E
authors.lastname: Lugo-Medina
authors.forename: Angel
authors.initials: A
authors.lastname: Licea-Claverie
mesh_terms: D002412:Cations; D003692:Delayed-Action Preparations / Q000737:chemistry*; D004110:Diltiazem / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D009994:Osmolar Concentration; D011073:Polyamines / Q000138:chemical synthesis*; D000071228:Polyelectrolytes; D011109:Polymethacrylic Acids / Q000138:chemical synthesis*; D011433:Propranolol / Q000737:chemistry; D012995:Solubility; D013329:Structure-Activity Relationship; D013607:Tablets; D013696:Temperature; D014700:Verapamil / Q000737:chemistry
chemical_list: D002412:Cations; D003692:Delayed-Action Preparations; D004110:Diltiazem; D011073:Polyamines; D000071228:Polyelectrolytes; D011109:Polymethacrylic Acids; D011433:Propranolol; D013607:Tablets; D014700:Verapamil