Raloxifene hydrochloride (RLH) was formulated into a pH-modified supersaturatable\nself-microemulsifying drug delivery system (S-SMEDDS) to increase drug solubility and dissolution\nrate. Optimal formulations of pH-modified S-SMEDDSs were developed by incorporating\nhydroxypropyl-cellulose-L as a precipitation inhibitor and phosphoric acid as a pH modifier (an\nacidifier). RLH was dissolved to greater extents by all pH-modified S-SMEDDSs compared with\nnon-pH-modified S-SMEDDSs. In particular, phosphoric acid afforded greater drug dissolution than\ndid the other acidifiers tested, perhaps because phosphoric acid better controlled the pH. More than\n50% of the RLH was released from the pH-modified S-SMEDDS at pH 2.5 compared with only ~5%\nof the drug into aqueous buffer (pH 1.2 or 6.8) after dissolution of a conventional tablet. pH-modified\nS-SMEDDSs with a hydrophilic polymer and phosphoric acid improved the dissolution behavior\nof a drug exhibiting poor aqueous solubility.
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