Development and Evaluation of Carbon Nanotubes Doped Sustained Release Microspheres of Metoprolol Tartrate.

A highly water soluble antihypertensive drug, metoprolol tartrate (MT) was selected as a model drug for preparation ofmulti-walled carbon nanotubes (MWCNTs) impregnated ethyl cellulose (EC) microspheres with aim to increase encapsulation efficiency and sustained release rate. Carbon nanotubesdrug adsorbate (MWCNTs:MT) loaded EC microspheres were optimized by Central Composite Design of experiment. The effects of independent variables (MWCNTs:MT and EC:adsorbate) were evaluated on responses like entrapment efficiency (EE) and time required for 50% drug release (t50). Furthermore, desirability approach was adopted to select best batch. The results revealed improvement in encapsulation efficiency for MWCNTs:MTloaded EC microspheres. In vitro drug release study exhibited complete release form drug alone microspheres within 14 h while MWCNTs impregnated EC microspheres exhibited only 50-60 % drug release in 14 h.The optimized batch was further characterized by various instrumental analysis which endorse encapsulation of MWCNTs:MT adsorbate inside the matrix of EC microspheres which resulted in enhanced encapsulation and sustained effect of MT.