Development of a ceramic device for continuous delivery of acetylsalicylic acid

Acetylsalicylic acid (aspirin) is a commonly used analgesic. The recommended postoperative regimen of aspirin administration for animals is every four to six hours for seven to ten days. This procedure requires repeated restraint of the animal, which increases the risk of injury to both the animal and laboratory/veterinary personnel. Therefore, development of a biodegradable, implantable ceramic device for continuous delivery of effective amounts of aspirin for seven to ten days should alleviate the above problems. Experiments conducted to date have shown that aspirin can be delivered in effective amounts by a ceramic matrix device in rats for six days. Thus, additional variables had to be tested in an attempt to slow the rate of release. The variables tested in this experiment were compression load at which the ceramic matrix is pressed, sintering the ceramic, the ceramic to aspirin ratio, incorporation of Vitamin E oil in the ceramic, and insertion of a compressed aspirin pellet in the ceramic matrix. The ceramic device that accomplished the longest release (six continuous days in vitro) was a combination of an aspirin insert (150 mg), a 3:1 ratio of dry HA to oil saturated HA (375 mg dry HA and 125 mg oily HA), and 2 mg erythromycin pressed together at 10000 lbs in a 10 mm steel die. It has been shown that 24 hours (one day) in vitro release corresponds to about 48 hours (two days) in vivo release, suggesting this system will release aspirin for at least 12 days in animals.