Pharmacokinetics and Renal Toxicity of Monomeric Amphotericin B in Rats after a Multiple Dose Regimen.

BACKGROUND

Delivery of monomeric Amphotericin B (AmB), i.e. deaggregated AmB, has been a major tactic in the reduction of renal toxicity at a membrane level, taking advantage of the selectivity of monomeric AmB for binding ergosterol over cholesterol.

OBJECTIVE

The aim of this study was to characterize the pharmacokinetic (PK) and renal toxicity of monomeric AmB in rats following a multiple dose regimen.

METHOD: AmB existed primarily in a monomeric state in poly(ethylene glycol)-block-poly(N-hexyl stearate L-aspartamide) (PEG-b-PHSA) micelles (mAmB) at 2:1 ratio (mol:mol), whereas AmB as its standard formulation, Fungizone®, was highly self-aggregated based on absorption spectroscopy.

RESULTS

After single intravenous injection, mAmB significantly (p < 0.001) increased the area under the plasma drug concentration-time curve (AUC) and reduced the volume of distribution (Vd) and total systemic clearance (CL) relative to Fungizone®. After daily intravenous injections at dose of 1.0 mg/kg for 7 days, PK parameters of mAmB and Fungizone® were similar to day 1. The treatment of Fungizone® also significantly (p < 0.05) increased levels of urinary enzymes, N-acetyl-β-D-glucosaminidase (NAG) and kidney injury molecule-1 (KIM-1) by 3.1- and 3.0 fold, respectively, whereas levels of NAG and KIM-1 were unchanged for mAmB, consistent with hematoxylin and eosin (H&E) staining of excised kidneys.

CONCLUSION

In summary, mAmB has less renal toxicity than AmB as Fungizone® in rats after a multiple dose regimen, validating the aggregation state hypothesis of AmB in vivo.