In vitro release of azidothymidine (AZT) by ceramic drug delivery systems

Conventional methods of administration of 3-azido-2,3-dideoxythymidine (AZT) to treat AIDS patients is associated with negative side effects, including toxic effects on bone marrow. This study was designed to investigate the capability of tricalcium phosphate (TCP) and alumino-calcium-phosphorous oxide (ALCAP) drug delivery systems to release AZT in a sustained manner in an in vitro environment. A total of 35 TCP and 35 ALCAP ceramic capsules were used in this experiment. The final densities of the ceramics were 1.68 +/- 0.11 and 1.58 +/- 0.08 g/cm3 for ALCAP and TCP, respectively. Tricalcium phosphate ceramics were distributed into four groups. Each ceramic in groups I, II and III (n = 10) was loaded with 20, 40, or 60 mg of AZT in powder form, respectively. Group IV ceramics (n = 5) were left empty and served as a control group for possible corrections of absorbance readings. A similar protocol was followed for ALCAP ceramic capsules unless otherwise indicated. All TCP and ALCAP ceramic capsules were sealed at both ends with Silastic Medical Adhesive Silicon Type A (Dow Corning, Midland, MI). Each empty capsule and those loaded with AZT were sealed and suspended in a capped and sealed individual serum bottles containing 100 mls of phosphate buffered saline (pH 7.4), and agitated at 100 cycles per min in a water bath at 37 degrees C. The amount of AZT released from the ceramic reservoir into the buffered medium was measured spectrophotometrically (265 nm). Release of AZT from the ceramic capsule was monitored until the contents of the capsules were depleted.(ABSTRACT TRUNCATED AT 250 WORDS)