Carbon Nanotube as Adsorbent for Floating Microspheres of Diltiazem Hydrochloride

Abstract

Diltiazem hydrochloride (DTZ), a highly water soluble antihypertensive drug, was used as a model drug for the incorporation of drug‐carbon nanotube adsorbates microspheres. These microspheres were characterized by yield, drug entrapment efficiency, micromeritics, flow properties, buoyancy, scanning electron microscopy (SEM), powder X‐ray diffractometry (PXRD) and drug release kinetics. Studies on carbon nanotubes (CNT) doped microspheres showed that the total yield of microspheres was independent of CNTs incorporated. Size, shape, circularity and flow properties of microspheres for all batches were not affected by the incorporation of CNTs. Microspheres of all batches had uniform size distribution, very good shape and circularity as well as flow properties. Drug entrapment efficiency of microspheres containing adsorbates was more compared to microspheres containing drug alone; hence CNTs can be considered as a good carrier for improving drug entrapment. Drug entrapment efficiency was found to be 82–94wt.% for CNT doped microspheres while only 63–74wt.% for microspheres without CNTs. Buoyancy of the microspheres containing CNT was found to be little bit more (77–86%) as compared to the buoyancy of microspheres without CNT (77–81%). Drug was released completely in 10 hours from microspheres without CNT, while only 50–60% of drug was released from CNT microspheres in 10 hours and the release of drug followed Higuchi matrix model due to diffusion of drug through the microspheres. From the existing data it was concluded that physical interaction between drug and CNTs exists, and being inert in nature, they can be used as novel carriers for extended drug release purpose and improving drug entrapment efficiency of microspheres.