EFFECT OF GELATION CONDITIONS AND DISSOLUTION MEDIA ON THE RELEASE OFPARACETAMOL FROM ALGINATE GEL BEADS

Paracetamol was entrapped in alginate beads gelled with calcium or zin c at 0.1, 0.34 or 0.7M. The payloads were of the order of 60-70% w/w w hich represented an entrapment yield of > 75%. The release of drug fro m the beads was observed in three media; water, Simulated Gastric Flui d USP without pepsin (SGF) and 0.1% trisodium citrate solution. Releas e was slowest in water and was complete within 4-5 h. The zinc beads r eleased more slowly than calcium beads prepared at the same molar conc entration of cation. Complete release of drug from the alginate gel be ads in SGF occurred within 2 h and was unaffected by the cation type a nd concentration. Except for beads prepared from 0.1M zinc, paracetamo l was released rapidly in the citrate solution. All release profiles c ould be described by first-order kinetics with half-lives which ranged from 25-73 min. Due to the rapid release in acidic conditions, it is unlikely that alginate beads loaded with a relatively water soluble dr ug will provide satisfactory prolonged release orally.