Effect of tabletting compaction pressure on alginate microspheres

Alginate and alginate-hydroxypropylmethylcellulose (HPMC) microspheres were prepared by the emulsification method. The compaction of microspheres for producing tablet dosage forms raises concerns about possible damage to micr osphere walls with subsequent unpredictable dissolution rates. The effect o f different compaction pressures on the integrity of the microspheres was i nvestigated. The addition of a diluent, microcrystalline cellulose (MCC), w as required to make compacts containing alginate and alginate-HPMC microsph eres. Compacts containing alginate-HPMC (7:3) microspheres had the highest crushing strength followed by compacts containing alginate-HPMC (9:1) micro spheres and alginate microspheres. However, compact crushing strength did n ot vary significantly with increased compaction pressures over the range of compaction pressures investigated. Differences in the drug release profile s of the original non-compacted and compacted alginate and alginate-HPMC mi crospheres were slight and not marked. Although dentation and distortion of the microspheres were observed with increasing compaction pressures, the m icrospheres generally remained intact, with minimal rupture/fracture.