Application of Physiologically Based Pharmacokinetic Model to Compare the Biodistribution of Liposomal Amphotericin B With Conventional Amphotericin B Deoxycholate in Humans

Amphotericin B (AmB) has been a cornerstone in the treatment of invasive fungal infections for over 6 decades. Compared with conventional amphotericin B deoxycholate (AmB-DOC), liposomal amphotericin B has comparable efficacy but less nephrotoxicity. The main purpose of this study was to investigate the reason why liposomal amphotericin B has similar therapeutic effects but lower toxicity and the differences of distribution in humans between liposomal amphotericin B and AmB-DOC. To compare the distribution of liposomal amphotericin B and AmB-DOC in humans, the physiologically based pharmacokinetic (PBPK) model was established by bottom-up stepwise method. A rat PBPK model was established firstly, then verified in mouse level in consideration of interspecies differences in physiological- and drug-specific parameters, and finally the PBPK model was extrapolated to humans. Based on preclinical and clinical pharmacokinetic (PK) studies, the AmB-DOC and liposomal amphotericin B PBPK model were established, respectively. The simulated results of human PBPK model showed that the liposomal formulation changed the pharmacokinetic characteristics of AmB. Compared with AmB-DOC, the plasma exposure of liposomal formulation was higher, but the renal exposure was significantly reduced.