The main aim of the present investigation is to study of formulation, development and characterization of floating mcrospheres of verapamil hydrochloride. Floating microspheres with a central hollow cavity were prepared by using a modified Quasi-emulsion diffusion technique. Weighed quantities of verapamil hydrochloride, ethyl cellulose, polyethylene oxide and hydroxy propylmethyl cellulose (HPMC K15M) were dissolved in a mixture of ethanol and dichloromethane (1:1 solvent ratio) at room temperature in a magnetic stirrer at 50 rpm for 50 min. The samples were assayed for drug content using UV spectrophotometer at 228 nm after suitable dilution. No interference was found due to the other components of floating microspheres at 228 nm. The yield was determined by weighing the microspheres and then the percentage yield was calculated with respect to the weight of the input materials, i.e., weight of verapamil and polymers used. The polymers like ethyl cellulose, eudragit L 100, polyethylene oxide and HPMC were selected for hollow microspheres preparation. These formulations contained ethyl cellulose (2%) and Polyethylene oxide (1%), HPMC K15M (1%) & eudragit L100 (1%) respectively. The encapsulation efficiency ranged between 53 ± 2.2 to 89 ± 1.9%, and was observed that the encapsulation efficiency increased with increasing amount of polymers in the hollow microspheres. The sphericity factors for all formulations were in the range of 1.01 ± 0.2 to 1.29 ± 0.6 and the sphericity values of best formulations F3, F7 and F9 were 1.05±0.2, 1.07 ± 0.1 and 1.16 ± 0.1 respectively. Quassi emulsion method used for preparation of hollow microspheres was suitable for poor water soluble drugs, because the drug was soluble in the internal organic phase.
Particle Characterization of Poorly Water-Soluble Drugs Using a Spray Freeze Drying Technique
