Factors influencing the fabrication of albumin-bound drug nanoparticles (ABDns): part I. Albumin-bound betulinic acid nanoparticles (ABBns).

Though there are many albumin-based drug delivery systems (ABDDS) in the market, it is not known whether ABDDS can be applied across all chemical classes. In this study, we applied ABDDS to a poorly water-soluble drug betulinic acid (BA) to improve its aqueous solubility. Monomeric albumin-bound BA (ABBns) nanoparticles can be fabricated in the range of 10-20 nm. BA self-assembled with HSA at 0.1:1 to 2:1 molar ratio within 0.5 h in phosphate buffer pH 7.4 and 8.4. Approximately, 85-90% BA could be loaded onto HSA in the presence of Tween 20 (T20) and sodium cholate (NaC). The release of BA from ABBns was linear over 5 days. In conclusion, for poorly water-soluble acidic drugs, a suitable solubiliser can release the drug from HSA binding site, depending on the aggregation number and affinity of the solubiliser for the HSA binding site.