Release control of theophyline from plasmairradiated double-compressed tablet composed of polylactic acid as a wall material.

Abstract

Oxygen plasma-irradiation(radio frequency discharges operating at 13.56 MHz with less than 10 W) on the compressed tablet of one of the bioerodible polymers, polylactic acid(PLA), was found to cause only low efficiency in its degradation to such an extent as has been observed with polystyrene. Thus, controlled-release tablets have been obtained by oxygen plasma irradiation on the outermost layer of the double-compressed tablet which were fabricated from theophylline tablet as a core materials and a mixture of plasma-degradable polyoxymethylene (POM) and bioerodible PLA as a wall material. Dissolution test clearly indicated that the theophylline has been released from the tablet through the resulting micropore, while the release from untreated tablets was negligible. It was also found that dissolution profiles are capable of being varied so as to cause release of theophylline at different rates, depending on the set of conditons chosen for tablet fabrication as well as plasma operational conditions.