Aliskiren Hemifumarate Proliposomes for Improved Oral Drug Delivery: Formulation Development, In Vitro and In Vivo Permeability Testing

Abstract

The objective of this study was to develop proliposomal formulations for a poorly bioavailable drug, aliskiren hemifumarate (AKH). A solvent evaporation method was used to prepare proliposomes using different lipids. The lipids of selection were soy phosphatidylcholine (SPC), dimyristoylphosphatidylcholine (DMPC), and dimyristoylphosphatidylglycerol sodium (DMPG Na), stearylamine, and cholesterol in various ratios. Proliposomes were evaluated for particle size, zeta potential, in vitro drug release, in vitro permeability, and in vivo pharmacokinetics upon hydration with aqueous phase. In vitro drug release studies were conducted in 0.01 N hydrochloric acid using USP type II dissolution apparatus. Parallel artificial membrane permeation assay (PAMPA) and Caco-2 cell line models were used to study the in vitro drug permeation. Male Sprague-Dawley (SD) rats were used to conduct in vivo pharmacokinetic studies. Among different formulations, proliposomes with drug/DMPC/cholesterol/stearylamine in the ratio of 1:5:0.025:0.050 (w/w/w/w) demonstrated the desired particle size, higher zeta potential, and higher encapsulation efficiency. The PAMPA and Caco-2 cell line experiments showed a significantly higher permeability of AKH with proliposomes as compared to pure AKH. In animal studies, the optimized formulation of proliposomes showed significant improvement in the rate and extent of absorption of AKH. Specifically, following a single oral administration, the relative bioavailability of AKH proliposome formulation was 230% when compared to pure AKH suspension.

Keywords: Caco-2; PAMPA; aliskiren hemifumarate; pharmacokinetic studies; proliposomes.

Figure 1

Chemical structures of (A) aliskiren hemifumarate and (B) hydrochlorothiazide (IS).

Figure 2

Microscopic image of proliposomes (F8) after hydrating with purified water.

Figure 3

DSC thermograms of AKH and proliposomal formulation (F8).

Figure 4

In vitro release profile of AKH pure drug and liposomal formulations in 0.01 N HCl (n = 3). Time (min) vs. Cumulative % drug release; $$$$—F7 (Liposome) vs. F8 (Liposome) with significance p < 0.0001; $$—F7 (Liposome) vs. F8 (Liposome) with significance p = 0.0012; ****—AKH Pure drug vs. F7 (Liposome) with significance p < 0.0001; ####—AKH Pure drug vs. F8 (Liposome) with significance p < 0.0001; ##—AKH Pure drug vs. F8 (Liposome) with significance p = 0.0086; ns—F7 (Liposome) vs. F8 (Liposome), AKH Pure drug vs. F7 (Liposome), AKH Pure drug vs. F8 (Liposome) are non-significant.

Figure 5

Average cumulative concentrations of AKH and proliposomal formulation.

Figure 6

LCMS/MS chromatograms of hydrochlorothiazide (IS) and aliskiren hemifumarate.

Figure 7

Mean plasma concentrations of AKH following oral administration of pure drug and its proliposomal formulation (F8). ####—Pure drug vs. F8 (Proliposome) with significance p < 0.0001; #—Pure drug vs. F8 (Proliposome) with significance p = 0.0409; ns—non-significant.

Figure 8

In vitro release profile of AKH pure drug and proliposomal formulation of initial and 3 M stability samples in 0.01 N HCl (n = 3). Time (min) vs. Cumulative % drug release; ####—AKH pure drug vs. F8 (Proliposome) Initial with significance p < 0.0001; ****—F8 (Proliposome) Initial vs. F8 (Proliposome) 3 M, 40 °C/75% RH with significance p < 0.0001; ns—F8 (Proliposome) Initial vs. F8 (Proliposome) 3 M, 40 °C/75% RH is non-significant.