Increasing CAP concentration could be an option to increase the quantity of BTB, as this API is soluble in this excipient. However, it is not a good alternative since the region of greatest heterogeneity occurred when the Capryol ® 90 concentration is higher than 36.67% (w/w) (Figure ). Therefore, although this mixture of excipients is more promising than that of CP:Dhaykol 6040 LW, the concentration of 5.0% (w/v) BTB is very close to the solubilization limit of the NLC formulation.