The role of sodium alginate on the supersaturation state of the poorly soluble drug chlorthalidone.

Solid dispersions (SDs) of chlorthalidone (CTD) are promising systems to enhance drug dissolution rate, generate and maintain drug supersaturation levels in gastrointestinal fluids. In this work, SDs of CTD were prepared by spray drying using sodium alginate (SA) as carrier. Six formulations were prepared, varying the drug loading and composition, through the combination of SA with surfactants (sodium lauryl sulfate (SLS) or polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer (SOL)). In all SDs, except when SA was used alone at low drug loading, CTD was in the amorphous form. At sink conditions, all SDs showed a faster dissolution rate than the crystalline drug. At non-sink conditions, the SDs prepared with SA and SLS at low drug loading exhibited the best performance to maintain supersaturating drug levels. All SDs, except those prepared with SA alone or SA-SLS at high drug loading, presented no drug recrystallization after 34 months of storage.