FORMULATION AND EVALUATION OF ASCORBIC ACID EXTENDED RELEASE HYDROPHYLLIC MATRIX TABLETS BY USING HYDROXYPROPYL METHYLCELLULOSE AND POLYETHYLENE OXIDE AS MATRIX FORMING POLYMERS

Aim: Developing extended release matrix tablets containing 350 mg ascorbic acid and hydroxypropyl methylcellulose (HPMC) or polyethylene oxide (PEO) as hydrophilic polymer/s which control the rate and degree of drug release through 12 hour period. Materials and methods: Six batches of matrix tablets (P1, P2, P3, P4, P5, P6) were produced by direct compression. Ascorbic acid 97% was used as active compound. HPMC K4M, HPMC K15M, PEO 1105 and PEO 301 were used as hydrophilic polymers. Cellulose microcrystaline was used as diluent, copovidone was employed as binder, colloidal silica as flow-aid while magnesium stearate was used as lubricant. Before tableting powder mixtures were sieved and evaluated for bulk density, tapped density, angle of repose, compressibility index and Hausner ratio. Compressed tablets were evaluated for average mass, hardness, friability, average drug content and dissolution profile through 12 hours in phosphate buffer pH=7.2 . All test were conducted according pharmacopoeial standards (PhEur 7 and USP 35) Results: All six batches of powder mixtures demonstrated good flow properties and didn’t tend to make any problems during tableting process. Also all six batches of tablets complied the pharmacopeial requirements concerning average mass, hardness, friability and drug content. Dissolution studies demonstrated that all six batches of tablets provided extended release of ascorbic acid through 12 hours period, but only tablets containing PEO 1105, PEO 301 and their 1:1 mixture liberated more than 80% active compound, which is generally due to the lower viscosity and higher erodability of these PEO-s compared with the used HPMC-s. It was also demonstrated that low viscosity PEO 1105 or HPMC K4M released higher percent of active compound compared with higher viscosity PEO 301 or HPMC K15M, while both PEO 1105/PEO 301 1:1 mixture and HPMC K4M/HPMC K15M 1:1 mixture gave intermediate drug release, which is connected to the intermediate viscosity obtained by mixing these polymers. Conclusion: From the results received from all test it was concluded that tablets containing PEO 1105 as hydrophilic polymer (P1) are the most suitable choice for developing 12 hour extended release matrix tablets containing 350mg ascorbic acid as active compound.