Assessment of hot-processability and performance of ethylcellulose-based materials for injection-molded prolonged-release systems : an investigational approach

The present work focuses on application of an investigational approach to assess the hot-processability of pharmaceutical-grade polymers with a potential for use in the manufacturing of reservoir drug delivery systems via micromolding, and the performance of resulting molded barriers. An inert thermoplastic polymer, ethylcellulose (EC), widely exploited for preparation of prolonged-release systems, was employed as a model component of the release-controlling barriers. Moldability studies were performed with plasticized EC, as such or in admixture with release modifiers, by the use of disk-shaped specimens ≥ 200 µm in thickness. The disks turned out to be a suitable tool for evaluation of the dimensional stability and diffusional barrier performance of the investigated materials after demolding. The effect of the amount of triethyl citrate, used as a plasticizer, on hot-processability of EC was assessed. The rate of a model drug diffusion across the polymeric barriers was shown to be influenced by the extent of porosity from the incorporated additives. The investigational approach proposed, of simple and rapid execution, holds potential for streamlining the development of prolonged-release systems produced by micromolding in the form of drug reservoirs, with no need for molds and molding processes to be set up on a case-by-case basis.