AIM To develop a novel pulsatile drug delivery system of which the lag time is cont rolled by an
erodible plug (EP) and
evaluate its release characteristics in vi tro . METHODS The impermeable capsule body was prepared by fulfilling method and the drug tabl et and the
erodible plug were made by wet granulating compression. Tetramethylpy razine phosphate (TMPP)
pulsincap capsule was prepared by sealing the drug table t and fillers inside the impermeable capsule body with the EP. The influence fac tors on the lag time such as the EP pharmaceutical properties and the dissoluti on condition were investigated by dissolution testing. RESULTS Both the composition and the weight of EP influenced the lag time of the tetram ethylpyrazine phosphate pulsincap capsule significantly. The lag time prior to the drug release was enhanced when the content of gel forming excipient (hydrox ypropylmethylcellulose, HPMC) in the EP or the weight of EP was increased. The h ardness of EP showed minor influence on the lag time. In addition, the lag tim e was shortened when the paddle speed was higher, while the pH value of the diss olution medium exhibited no significant influence on it. CONCLUSION To meet the chronotherapeutic requirements, a pulsatile drug delivery system wit h a suitable lag time can be achieved by adjusting the composition and the EP w eight.