D-Optimal experimental design

ABSRACT The aim of this study was to prepare a solid dosage form able to release theophylline after a maximum delayed time and at a maximum cumulative amount in 12 hours. To achieve this goal a blend of two polymers with different properties was used along with talc powder and utilizing D-expert statistical software package. The polymer blend consists of Eudragit NE 30D and Eudragit RL 30D-55. Solid precipitates composed from polymer blend and talc powder and containing a fixed amount of theophylline were prepared using spray dryer. The prepared solid precipitates were compressed into tablets and the dissolution profile of each formulation was investigated. Delayed time was observed in term of time required to release 10 % of the labeled theophylline. Delay time was ranged from 2.14 to 4.1 hour while, percent of theophylline released in 12 hours ranged from 84.06 to 97.94 %. After that optimization was performed to prepare a dosage form with a desired properties in term of maximum delayed time and maximum percent theophylline released in 12 hours. The optimized solid precipitates as generated from the statistical software package was formulated and investigated. The optimized formulation was able to delay the time of theophylline release to 3.24 hour and release 93.64 % of the incorporated theophylline in 12 hours. Solid dispersion technique in conjunction with statistical design was shown to be very efficient for the optimization of both the delayed time and cumulative amount of drug released in 12 hours. Keywords: D-Optimal experimental design, optimization, Theophylline, Delayed release