A ceramic system for continuous release of acetylsalicylic acid

This investigation was conducted to study the release of acetylsalicylic acid (ASA) from a beta-Tricalcium Phosphate (TCP) resorbable ceramic matrix (RCM) in Tris-HCl (pH 7.4, 0.5M) at 37 degrees C. Initial compression load studies were conducted for 12 hours. Compression load and dose-response studies were conducted for a total duration of seven days. Mixtures of 150 mg acetylsalicylic acid (Aspirin) and 500 mg TCP were compressed at loads of 2000, 3000, or 4000 lbs. Ceramics with 75, 150, 225, 300, or 375 mg of ASA were mixed with 500 mg TCP and compressed at 3000 lbs. Aliquots of Tris-HCl, taken at two hour intervals for the first 12 hours, and daily thereafter, were assayed spectrophotometrically for ASA at 245 nm. Differences in the amounts of ASA released by RCMs compressed at the three loads were not significant. Release of ASA from RCMs was linear only if the ceramic/ASA ratio was close to 6.67:1. Results of this investigation suggest that resorbable TCP ceramics can be used for continuous delivery of ASA for seven days.