Formulation and In vitro Evaluation of Metoprolol Succinate Extended Release Pellets

The objective of the present study was for improving bioavailability and reducing the dosage frequency of Metoprolol succinate in the form of extended release pellets by pan coating technology. Initially drug solution coated on different cores i.e. water soluble, insoluble and swellable cores and layered by different combinations of extended release polymers as EC(ethyl cellulose) 10 cps + HPMC (Hydroxy propyl methyl cellulose), EC 10 cps + Di ethyl phthalate and EC 10 cps + HPMC+ Diethyl phthalate. Formulated pellets were evaluated for flow properties, surface morphology, size analysis and in vitro dissolution studies. Studies were done on the effect of core nature and coating composition and effect of plasticizer. In vitro dissolution studies revealed that higher release observed from water-soluble core compared to insoluble and swellable cores. Controlled drug release observed from coating composition containing combination of EC + diethyl phthalate. Moderate drug release observed from combination of HPMC + EC+ diethyl phthalate. The mechanism of drug release follows Higuchi diffusion model. In conclusion the resulting formulations F6 (Water soluble core and coat was EC 10 cps + HPMC+ Di ethyl phthalate) can reduce the dosing frequency of the Metoprolol succinate to once daily