Structure and properties of polycaprolactone/ibuprofen rods prepared by melt extrusion for implantable drug delivery

In this study, the structure and properties of polycaprolactone/ibuprofen (PCL/IBP) rods prepared by melt extrusion were investigated by infrared spectroscopy, X-ray diffraction, scanning electron microscopy, flexural tests, dynamic mechanical analysis and drug release analysis. The crystallinity values for the PCL/IBP rods were lower than that for the pure PCL rods. The PCL/IBP rods had higher values for the flexural modulus compared with the pure PCL rods prepared using the same processing temperature, suggesting that ibuprofen has a hardening effect when dispersion in a PCL matrix. Rods prepared at a processing temperature of 130 °C had the highest flexural modulus and glass transition temperature, probably due to better drug dispersion in the PCL matrix at lower temperature. The surfaces of PCL/IBP rods prepared at 150 °C had small particles and molten drug was deposited on the surface. This is probably due to the low melt temperature of ibuprofen and thus at high temperatures the ibuprofen phase migrates from the PLC matrix to the rod surface. The PCL/IBP rods prepared using different processing temperatures provided different drug release behaviors, with fast or slow drug release depending on the ibuprofen distribution. This feature is of great interest in relation to producing implantable drug delivery rods for acute inflammatory crisis or therapeutic treatments via controlled release