Design and In Vitro Evaluation of Eudragit-Based Extended Release Diltiazem Microspheres for Once- and Twice-Daily Administration: The Effect of Coating on Drug Release Behavior.

Microspheres prepared with DL:Eud RL ratios of 1:3 and 1:4 showed release profiles in accordance with the USP criteria for a DL extended release product for dosing every 12 and 24 h, respectively.