Design of red blood cell membrane-cloaked dihydroartemisinin nanoparticles with enhanced antimalarial efficacy.

Targeting delivery and prolonging action duration of artemisinin drugs are effective strategies for improving antimalarial treatment outcomes. Here, dihydroartemisinin (DHA) loaded poly (lactic-co-glycolic acid) (PLGA) nanoparticles (PDNs) were prepared and further cloaked with red blood cell (RBC) membranes via electrostatic interactions to yield RBC membrane-cloaked PDNs (RPDNs). The prepared RPDNs displayed a notable "core-shell" structure, with a negative surface charge of -29.2 ± 4.19 mV, a relatively uniform size distribution (86.4 ± 2.54 nm, polydispersity index of 0.179 ± 0.011), an average encapsulation efficiency (70.1 ± 0.79%), and a 24-h sustained-release behavior in vitro. Compared with PDNs, RPDNs showed markedly decreased phagocytic activity by RAW 264.7 cells and had prolonged blood circulation duration. The Pearson correlation coefficient of RPDNs distribution in infected red blood cells (iRBCs) was 0.7173, suggesting that RPDNs could effectively target Plasmodium-iRBCs. In PyBy265-infected mice, RPDNs showed a higher inhibition ratio (88.39 ± 2.69%) than PDNs (83.13 ± 2.12%) or DHA (58.74 ± 3.78%), at the same dose of 8.8 µmol/kg. The ED90 of RPDNs (8.13 ± 0.18 µmol/kg) was substantially lower than that of PDNs (14.48 ± 0.23 µmol/kg) and DHA (17.67 ± 3.38 µmol/kg). Furthermore, no apparent abnormalities were detected in routine blood examination, liver function indexes, and pathological analysis of tissue sections of PyBy265-infected mice following RPDNs treatment. In conclusion, the prepared RPDNs exhibited enhanced antimalarial efficacy, prolonged circulation, targeted delivery to Plasmodium-iRBCs, and satisfactory biocompatibility.

Murine pharmacokinetics and antimalarial pharmacodynamics of dihydroartemisinin trimer self-assembled nanoparticles.

Currently, conjugation of artemisinin-derived dimers, trimers, and tetramers is a viable strategy for developing new effective antimalarial candidates. Furthermore, nanotechnology is an effective means to achieve intravenous administration of hydrophobic drugs. In this paper, an ester-linked dihydroartemisinin trimer (DHA3) was synthesized and further prepared as self-assembled nanoparticles (DHA3NPs) by a one-step nanoprecipitation method. The pharmacokinetics and antimalarial pharmacodynamics of DHA3NPs were studied in rats and mice infected with Plasmodium yoelii BY265 (PyBY265). DHA3NPs had a regular spherical shape with a uniform size distribution of 140.27 ± 3.59 nm, entrapment efficiency (EE) of 99.63 ± 0.17%, and drug loading efficiency (DL) of 79.62 ± 0.11%. The in vitro release characterization revealed that DHA3NPs were easily hydrolysed into DHA in an esterase environment. The pharmacokinetics study demonstrated that the area under the concentration-time curve (AUC0-t) of DHA in DHA3NPs group was 2070.52 ± 578.76 h×ng×mL-1, which was higher than that of DHA and artesunate (AS) control groups (AUC0-t values of 724.18 ± 94.32 and 448.40 ± 94.45 h×ng×mL-1, respectively) (P < 0.05). The antimalarial pharmacodynamics in vivo suggested that DHA3NPS (ED90 7.82 ± 1.16 µmol×(kg×day)-1) had a superior antimalarial effect compared with that of control groups (ED90 values of 14.68 ± 0.98 (DHA) and 14.34 ± 1.96 (AS) µmol×(kg×day)-1) (P < 0.05). In addition, DHA3NPS reduced the recurrence ratio and improved the cure ratio and survival time. In summary, DHA3NPs exhibited promising pharmacokinetic characteristics and antimalarial pharmacodynamics in vivo.

Choline and PEG dually modified artemether nano delivery system targeting intra-erythrocytic Plasmodium and its pharmacodynamics in vivo.

OBJECTIVE: The choline derivative (CD) and polyethylene-glycol (PEG) dually modified artemether (ARM) nanostructured lipid carriers (CD-PEG-ARM-NLC) have been designed to prolong the circulation of ARM in blood, as well as to develop targeting for new permeability pathways (NPPs) and erythrocyte choline carriers (ECCs) that are expressed on the Plasmodium-infected erythrocyte membrane. SIGNIFICANCE: The CD-PEG-ARM-NLC constructed in this study was found to be able to target endoerythrocytic Plasmodium by increasing the drug concentration and residence time in the infected erythrocytic microenvironment and minimizing toxicity and side effects. METHODS: CD-PEG-ARM-NLC was prepared using high-pressure homogenization followed by physicochemical characterization. The targeting ability of CD-PEG-NLC to infected erythrocytes probed by coumarin-6 was investigated by using fluorescence microscopy imaging. The SYBR Green I assay for parasite nucleic acid was adapted in order to assess the efficacy of inhibition against parasite growth in vitro. The antimalarial activity of ARM-loaded NLCs was evaluated by a Pearson four-day suppressive test in Pyy265BY-bearing mice. RESULTS: In vitro imaging indicated that the intracellular delivery of CD-PEG-ARM-NLC was efficiently taken up by the infected erythrocytes via ECCs and NPPs, which could be inhibited by addition of furosemide (an inhibitor of NPPs) and excessive choline (native substrate of ECCs). Moreover, in vitro and in vivo studies that evaluated antimalarial activity suggested that CD-PEG-ARM-NLC exhibited higher antimalarial activity in comparison to ARM-NLC and PEG-ARM-NLC. CONCLUSION: These findings suggested that choline and PEG dually modified NLC could be promising preparations for the production of hydrophobic antimalarial drugs, particularly for ARM.

Auto-Induction of Intestinal First-Pass Effect Related Time-Dependent Pharmacokinetics of Artemisinin Rather than Dihydroartemisinin.

Artemisinin (ART) drugs showed declining plasma concentrations after repeated oral dosing, known as time-dependent pharmacokinetics (PK). ART and dihydroartemisinin (DHA) were adopted as representatives to evaluate the roles of first-pass effects and systemic metabolism in time-dependent PK by comparison of oral versus intravenous administration and 1 dose versus 5 consecutive doses PK in rats and dogs, respectively. The hepatic extraction ratio (ERh) and the intestinal elimination changes were further investigated in rats to distinguish the roles of hepatic first-pass effect or intestinal first-pass effect. The induction capacities of ARTs to cytochrome P450 (CYP450) in rats and human cells were evaluated as well. For ART, only the oral groups showed time-dependent PK. A fairly high ERh that obtained for ART was not sensitive to multiple oral doses. An increased elimination and CYP450 expression have also been found in the intestine. For DHA, though a significant CYP450 induction was observed, neither time-dependent PK nor changes in the first-pass effects was found. In conclusion, time-dependent PK of ART was mainly caused by the increased intestinal first-pass effect rather than hepatic first-pass effect or systemic metabolism. DHA was not involved in auto-induction elimination, thus showing no time-dependent PK.

A two-step strategy to design high bioavailable controlled-release nimodipine tablets: the push-pull osmotic pump in combination with the micronization/solid dispersion techniques.

In order to decrease the fluctuation of blood concentration and to increase the oral bioavailability of nimodipine (NMD), a two-step strategy including the push-pull osmotic pump (PPOP) method in combination with micronization and solid dispersion techniques, was used to prepare the controlled-release high-bioavailability solid dosages. The optimization of formulation and process was conducted by comparing effects of different solubilization methods on release behavior of NMD. The in vitro dissolution studies indicated that both the two strategies were able to deliver NMD in the predetermined zero-order manner from 2 to 12h, regardless of effects of release media and agitation rates. Although the Cmax values of two PPOP tablets were lower than that of the reference formulation, both the Tmax values were prolonged, demonstrating the prominent controlled release performance. In comparison with the commercial reference tables, the relative bioavailability of the two formulations was 67.0% and 121.1%, respectively, indicating the solid dispersion technique was more efficient than the micronization technique in terms of solubilization capability and absorption enhancement. In summary, the two-step strategy, combining the push-pull osmotic pump method with the solid dispersion technique, is a very effective method to prepare high bioavailable controlled-release formulations of the poorly soluble drugs, i.e. NMD, taking into account the therapeutical efficiency and safety.