POLY(ALKYL VINYL ETHER COPOLYMERS) AS PROTECTIVE AND CONTROLLED RELEASE PHARMACEUTICAL FILM COATINGS (POLYALKYL)

Selected vinyl copolymers, alone and in combination with plasticizers, were screened and evaluated for possible application as pharmaceutical tablet film-coating systems. Based on an evaluation of physical and mechanical properties of free films, selected polymer candidates were modified and tested for possible applications as soluble, enteric release or sustained release tablet film-coatings. A high molecular weight grade of poly(methyl vinyl ether/maleic anhydride) was found to be best suited for tablet film-coating, carried out by both spray and immersion techniques. The chemical functionality of this polymer enabled the development of tablet film-coating systems, based on new and unique technological concepts. Hydrophobic film systems were applied to tablets with subsequent mild humidity and temperature conditioning to render films soluble in aqueous media for rapid tablet disintegration. The addition of reactive, polyfunctional plasticizers to similar polymer systems just prior to tablet film-coating, produced insoluble film-coatings due to polymer-plasticizer esterification/cross-linking reactions within the applied films. Completed reactions before film application, resulted in insoluble products which could not be used to coat tablets. Insoluble, applied systems of reacted polymer and plasticizer swelled in aqueous media to allow controlled release of soluble tablet components depending on the polymer-plasticizer ratio in the film systems. Polymer-plasticizer reactions were studied using infrared analysis and plasticizer extraction methods, along with the characterization of water vapor transmission properties of free film systems. These studies indicated that the probable polymer-plasticizer reaction was that of esterification and/or cross-linking, and that the majority of plasticizer was chemically bound by the polymer. Water vapor transmission rates were affected by the degree or state of the polymer-plasticizer esterification, i.e., decreasing water vapor transmission rates with increasing polymer-plasticizer esterification. Poly(methyl vinyl ether/maleic anhydride) in the film systems studied, yielded film-coatings of unparalleled gloss and clarity, and due to polymer\u27s hardness, these features were essentially permanent in that films were resistant to marring. . . . (Author\u27s abstract exceeds stipulated maximum length. Discontinued here with permission of school.) UM