Development of a /spl beta/-tricalcium phosphate ceramic system for in vitro and in vivo release of acetaminophen

Acetaminophen is often used as a veterinary analgesic. Conventional methods of drug administration may lead to drug levels that periodically exceed and/or fall below therapeutic levels. This study investigated the ability of a /spl beta/-tricalcium phosphate ceramic delivery system to release acetaminophen in vitro and in vivo. In response to difficulties experienced with the use of Tris-HCl, ethanol was used as the in vitro media. One 12 hour and one seven day study examined the effects of compression load on the acetaminophen release profile from the ceramic device. Differences in compression loads did not affect the release profiles of acetaminophen from the ceramic device. The effects of different acetaminophen dosages were investigated in one 12 hour and one four day study. The initial amount of drug loaded in the ceramic device significantly changed release profiles of acetaminophen. An in vivo study investigated the ability of the ceramic matrix devices (CMDs) to release acetaminophen for a minimum of seven days. Pain tolerance levels were tested and circulating analgesic levels were determined. Animals implanted with ceramic devices containing acetaminophen displayed significantly higher levels of circulating analgesic and pain tolerance. These studies suggest that it is possible to effectively deliver acetaminophen by means of a /spl beta/-tricalcium phosphate ceramic device, both in vitro and in vivo.