Formulation and evaluation of extended release microspheres loaded with labetalol

Microspheres loaded with Labetalol were prepared using chitosan as the polymer and TPP as the crosslinking agent. The formulation of micropsheres was done at various concentrations of the polymer and TPP. All the microsphere formulations (F1 to F6) were characterized for yield, entrapment efficiency, rheological properties (angle of repose, bulk density, tapped density, Hausner's ratio, Carr's index), and in vitro drug release. The pharmacokinetic release profile of drug from all the formulations was determined using zero order, Higuchi equation and KorsemeyerPeppas release model.The particles were found to be in the range of 600-1100 µm and the percentage yield varied from 64-83%.The drug entrapment efficiencies of different formulations were in the range of 64.26 to 86.00%. All the formulated microspheres exhibit good flow properties with a value of angle of repose between 21°32' to 29°72'. The Carr's index of all the formulations was found in the range 5.88 to 14.57 % indicating good flow ability. The Hausner's ratio of the formulations was found in the range 1.062 to 1.170. The cumulative drug release was observed to be 61.774%, 63.061%, 36.035%, 34.380%, 60.855% and 57.178% for the formulations F1 to F6 respectively. Consequently, it can be concluded that the microspheres produced from chitosan and TPP using ion gelation method is an excellent delivery system that has good extended release behavior and this would be beneficial in decreasing the dosing frequency of Labetalol in treatment of hypertensive conditions