Evaluation of hydroxypropyl methylcellulose phthalate 50 as film forming polymer from aqueous dispersion systems

Abstract

Hydroxypropyl methylcelluose phthalate 50 (HPMCP 50) was evaluated as a film forming polymer from aqueous dispersion systems. The influence of plasticizer type and level on the elasticity of HPMCP 50 free films prepared by the casting method was studied by measuring Young's modulus using an Instron Material Testing System. The release of a water soluble drug in various dissolution media from pellets coated with HPMCP 50 with 30% plasticizer containing various levels of hydroxypropyl cellulose (HPC) or hydroxypropyl methylcellulose (HPMC) was also studied. The influence of coating level on drug release from pellets was also investigated. Results showed that HPMCP 50 alone without a plasticizer does not form a film. However, when a plasticizer was added HPMCP 50 did form a film. Also, as the concentration of the plasticizer triethyl citrate was increased the elasticity of HPMCP 50 films was increased. Similar results were obtained with the plasticizer diethyl phthalate. For pellets a high coating level was required to achieve adequate protection in 0.06 N HCl. Drug release from coated pellets was found to be dependent upon the type and the level of the water soluble polymer incorporated with HPMCP 50. Drug release was increased as the percentage of HPC was increased. Higher release rates were obtained with HPMC compared to HPC. Coating level significantly influenced drug release in 0.06 N HCl; however, less of an effect was observed at pH 5.5.