Plasma lipoprotein distribution of liposomal nystatin is influenced by protein content of high-density lipoproteins

Abstract

The plasma lipoprotein distribution of free nystatin (Nys) and liposomal nystatin (L-Nys) in human plasma samples with various lipoprotein lipid and protein concentrations and compositions was investigated. To assess the lipoprotein distributions of Nys and L-Nys, human plasma was incubated with Nys and L-Nys (equivalent to 20 microg/ml) for 5 min at 37 degreesC. The plasma was subsequently partitioned into its lipoprotein and lipoprotein-deficient plasma fractions by step-gradient ultracentrifugation, and each fraction was analyzed for Nys content by high-pressure liquid chromatography. The lipid and protein contents and compositions of each fraction were determined with enzymatic kits. Following the incubation of Nys and L-Nys in human plasma the majority of Nys recovered within the lipoprotein fractions was recovered from the high-density lipoprotein (HDL) fraction. Incorporation of Nys into liposomes consisting of dimyristoylphosphatidylcholine and dimyristoylphosphatidylglycerol significantly increased the percentage of drug recovered within the HDL fraction. Furthermore, it was observed that as the amount of HDL protein decreased the amounts of Nys and L-Nys recovered within this fraction decreased. These findings suggest that the preferential distribution of Nys and L-Nys into plasma HDL may be a function of the HDL protein concentration.

FIG. 1

Lipid and protein contents and compositions within VLDLs (A), LDLs (B), and HDLs (C) of patient plasma samples 1 (□), 2 (), and 3 (⧫). TC, total cholesterol; CE, cholesteryl ester; fC, free cholesterol; TG, triglyceride; PL, phospholipid; TP, total protein. Data are represented as means ± standard deviations (n = 14). ∗, P < 0.05 versus patient sample 1; ∗∗, P < 0.05 versus patient sample 2.

FIG. 2

Distributions of free Nys (□) and L-Nys () in lipoprotein and lipoprotein-deficient fractions of patient plasma sample 1 (A), patient plasma sample 2 (B), and patient plasma sample 3 (C). Data are represented as means ± standard deviations (n = 8 for Nys; n = 6 for L-Nys). ∗, P < 0.05 versus Nys.

FIG. 3

Nys-to-total protein ratio within the four separated plasma fractions of three patient plasma samples following the incubation of Nys (A) or L-Nys (B) in human plasma for 5 min at 37°C. Data are represented as means ± standard deviations (n = 8 for Nys; n = 6 for L-Nys). ∗, P < 0.05 versus patient sample 1; ∗∗, P < 0.05 versus patient sample 2; N/D, nondetectable.

FIG. 4

Interaction of L-Nys with HDLs. apo AI, apolipoprotein AI; apo AII, apolipoprotein AII, PLTP, phospholipid transfer protein.