MECHANICAL-PROPERTIES OF DRY AND WET CELLULOSIC AND ACRYLIC FILMS PREPARED FROM AQUEOUS COLLOIDAL POLYMER DISPERSIONS USED IN THE COATING OF SOLID DOSAGE FORMS

The mechanical properties of dry and wet polymeric films prepared from various aqueous polymeric dispersions were evaluated by a puncture te st. They were studied with respect to type of polymer dispersion [cell ulosic: Aquacoat and Surelease; acrylic: Eudragit NE, L, RS, and RL 30 D], plasticizer type (water-soluble or water-insoluble), drying or cu ring conditions, method of film preparation (pseudolatex- vs solvent c asting) and ratio of Eudragit RS/RL 30 D in mixed Eudragit RS/RL films . Dry and wet mechanical strengths of the polymeric films depended pri marily on the types of the colloidal polymer dispersion and the plasti cizer. Films prepared from ethylcellulose dispersions resulted in very weak and brittle films when compared to the acrylic films. Pseudolate x-cast ethylcellulose films showed lower puncture strength and elongat ion values when compared to those of the solvent-cast films. Curing of the pseudolatex-cast ethylcellulose films had minimal effects on thei r mechanical properties. Eudragit L 30D, an enteric polymer dispersion , resulted in brittle films in the dry state, but in very flexible fil ms in the wet state because of the plasticization effect of water. Wet Eudragit RS 30 D polymer films plasticized with water-insoluble plast icizers were significantly more flexible than the corresponding wet fi lms plastizers with water-soluble plasticizers. The water-soluble plas ticizers leached from the films during exposure to the aqueous medium, while the water-insoluble plasticizers were almost completely retaine d within the wet films. The low permeability of a water-soluble drug, chlorpheniramine maleate, and the weak mechanical proper ties of Aquac oat films could suggest osmotic driven/rupturing effects as the releas e mechanisms from Aquacoat-coated dosage forms.