Preparation and evaluation of sustained-release diltiazem hydrochloride pellets

In this study, diltiazem hydrochloride (DTZ) pellets were prepared successfully by extrusion–spheronization method. Then methacrylic acid and ethylcellulose coating formulations were employed to make the DTZ pellets sustained release. The pellets with different coatings were investigated by in vitro dissolution tests. At last, the pellets with the best coating copolymer were subjected to pharmacokinetic studies in beagle dogs. The dissolution profiles of pellets coated with Eudragit® NE30D were similar to Herbesser®, one of the marketed sustained release capsules. In the bioavailability study, the principal pharmacokinetic parameters of self-made pellets and the marketed ones were comparable; the relative bioavailability of DTZ sustained release capsules compared with Herbesser® was 98.5 ± 36.4%. All the data indicated self-made sustained pellets could prolong the release of DTZ, decrease the fluctuation of drug level in vivo, and increase the compliance of patients.