Solubilization studies of tadalafil (TDF) have recently improved the dissolution (%) using weak acids and bases in our group. However, the weak acid formulations have a low dissolution (%) of TDF as limitation. Thus, the purpose of this study was to improve the dissolution (%) of TDF over 90% in distilled water (DW) by weak acid-chitosan based multi-system. The SD formulation (SD11: TDF, tartaric acid, chitosan, Aerosil®200, and PVP/VA S-630 in a 1:2:1:1:2 weight ratio) showed higher dissolution (%) of TDF by 5.0-, 6.0-, and 5.8-fold at 60 min than that of Cialis® in DW and pH 1.2 and pH 6.8 buffers, respectively. The physical properties of the SD11 formulation were changed. Moreover, the SD11 formulation maintained stability for 3 months. In conclusion, the solubilization of TDF using chitosan was successfully performed for the first time.
Keywords: Chitosan; Dissolution (%); Stability; Tadalafil; Weak acid.
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