Guar gum-based sustained release diltiazem.

PURPOSE

This study was performed to examine the use of guar gum to sustain the release of diltiazem under in vitro and in vivo conditions.

METHODS

Guar gum tablet formulations were prepared and evaluated under a variety of in vitro dissolution conditions. The formulations, along with Dilacor XR, were administered to a group eight fasted, healthy volunteers in a four period crossover study.

RESULTS

Varying the lot of guar gum as well as using guar from different suppliers had little effect on diltiazem dissolution. Also, dissolution of diltiazem from guar gum tablets was essentially independent of stir speed under normal conditions (USP Apparatus II) The stability of guar-based formulations under stressed conditions (40 degrees C/75% relative humidity for 3 months) was also established. All four formulations gave similar plasma concentrations over time in the healthy volunteers pharmacokinetic study.

CONCLUSIONS

Guar gum-based matrix tablets represent a simple and economical alternative to existing diltiazem sustained release dosage forms.