Microporous polycaprolactone matrices for drug delivery and tissue engineering: the release behaviour of bioactives having extremes of aqueous solubility

Microporons polycaprolactone (PCL) matrices loaded with hydrophobic steroidal drags or a hydrophilic drug pilocarpine hydrochloride were produced by precipitation casting using solutions of PCL in acetone. The efficiency of steroid incorporation in the final matrix (progesterone (56 %) testosterone (46 %)dexamethasone (80 %)) depended on the nature of the drug initially co-dissolved in the PCL solution. Approximately 90 % w/w of the initial load of progesterone, 85 % testosterone and 50 % dexamethasone was released from the matrices in PBS at 37 degrees C over 8 days. Pilocarpine hydrochloride (PH)-loaded PCL matrices, prepared by dispersion of powder in PCL solution, released 70-90 % of the PH content over 12 days in PBS. Application of the Higuchi model revealed that the kinetics of steroid and PH release were consistent with a Fickian diffusion mechanism with corresponding coefficients of 5.8 x 10(-9) (progesterone), 3.9 x 10(-9) (testosterone), 7.1 x 10(-10) (dexamethasone) and 2.2 x 10(-8) (pilocarpine hydrochloride). The formulation techniques described are expected to be useful for production of implantable, insertable and topical devices for sustained delivery of a range of bioactive molecules of interest in drug delivery and tissue engineering.