Performance of diltiazem tablet and multiparticulate osmotic formulations in the dog.

The in vivo performance of two extended-release (ER) osmotic formulations of diltiazem were evaluated in the beagle dog. Both ER formulations had similar bioavailabilities (F) as the diltiazem solution. Although F was somewhat variable following ER administration, this variability may be related to the drug entity since intra- and interanimal variability of orally administered diltiazem solutions was substantial. Deconvolution of the ER plasma diltiazem data with absorption data from the orally administered diltiazem solutions provided an estimate of the in vivo drug release from the ER formulations. The two ER formulations, designed with different in vitro release profiles, reflected these differences in vivo, with nearly identical respective in vivo and in vitro release profiles.