Multidrug PLA-PEG filomicelles for concurrent delivery of anticancer drugs—The influence of drug-drug and drug-polymer interactions on drug loading and release properties

Using a systematic and quantitative approach to generate new insights into drug loading of PLGA nanoparticles using nanoprecipitation

The synthesis of drug-loaded PLGA nanoparticles through nanoprecipitation in solvent/antisolvent mixtures is well reported but lacks clarity in explaining drug loading mechanisms and the prediction of efficiency of drug entrapment. Various methods using physical parameters such as log P and solid-state drug-polymer solubility aim to predict the intensity of drug-polymer interactions but lack precision. In particular, the zero-enthalpy method for drug/polymer solubility may be intrinsically inaccurate, as we demonstrate. Conventional measurement of loading capacity (LC), expressed in weight ratios, can be misleading for comparing different drugs and we stress the importance of using molar units. This research aims to provide new insights and critically evaluate the established methodologies for drug loading of PLGA nanoparticles. The study employs four model drugs with varying solubilities in solvent/antisolvent mixtures, log P values, and solid-state solubility in PLGA: ketoprofen (KPN), indomethacin (IND), sorafenib (SFN), and clofazimine (CFZ). This study highlights that drug loading efficiency is primarily influenced by the drug's solubilities within the solvent system. We emphasise that both kinetic and thermodynamic factors play a role in the behaviour of the system by considering the changes in drug solubility during mixing. The study introduces a pseudo-constant K* to characterise drug-polymer interactions, with CFZ and SFN showing the highest K* values. Interestingly, while IND and KPN have lower K* values, they achieve higher loading capacities due to their greater solubilities, indicating the key role of solubility in determining LC.

Advances in nanomedicines: a promising therapeutic strategy for ischemic cerebral stroke treatment

Ischemic stroke, prevalent among the elderly, necessitates attention to reperfusion injury post treatment. Limited drug access to the brain, owing to the blood-brain barrier, restricts clinical applications. Identifying efficient drug carriers capable of penetrating this barrier is crucial. Blood-brain barrier transporters play a vital role in nutrient transport to the brain. Recently, nanoparticles emerged as drug carriers, enhancing drug permeability via surface-modified ligands. This article introduces the blood-brain barrier structure, elucidates reperfusion injury pathogenesis, compiles ischemic stroke treatment drugs, explores nanomaterials for drug encapsulation and emphasizes their advantages over conventional drugs. Utilizing nanoparticles as drug-delivery systems offers targeting and efficiency benefits absent in traditional drugs. The prospects for nanomedicine in stroke treatment are promising.

Comparison of PLLA-PEG and PDLLA-PEG micelles for co-encapsulation of docetaxel and resveratrol

The interest in combining chemosensitizers with cytostatics in cancer therapy is growing, which causes also a need to develop their delivery systems. Example of the combination with beneficial therapeutic effects is docetaxel (Dtx) and resveratrol (Res). Although poly(lactide)-co-poly(ethylene glycol) (PLA-PEG) micelles have been considered as one of the most promising platforms for drug delivery, their properties may depend on the stereoisomeric form of hydrophobic block. Therefore, the aim of this study was evaluation of the effect of PLA block on co-encapsulation and release rate of Dtx and Res, which has not been studied so far. This article presents a comparison of single- (Dtx or Res) and dual-drug (Dtx and Res) loaded micelles obtained from poly(l,l-lactide)-co-poly(ethylene glycol) (PLLA-PEG) and poly(d,l-lactide)-co-poly(ethylene glycol) (PDLLA-PEG). The analyzes of the micelles have been conducted including morphology, drug(s) encapsulation efficiency, intermolecular interactions, in vitro drug release, and cytotoxicity. Differences in drug loading ability and release profile have been observed between Res and Dtx but also depending on the polymer and number of drugs in micelles (single vs. dual loaded). The PLLA-PEG micelles have a significantly higher Dtx encapsulation capacity than PDLLA-PEG micelles. The highest cytotoxicity was shown for Dtx and Res dual-loaded micelles, regardless of the polymer. The findings may be used for selection of PLA-based drug delivery systems containing Dtx and Res.

Selecting Counterions to Improve Ionized Hydrophilic Drug Encapsulation in Polymeric Nanoparticles

Hydrophobic ion pairing (HIP) can successfully increase the drug loading and control the release kinetics of ionizable hydrophilic drugs, addressing challenges that prevent these molecules from reaching the clinic. Nevertheless, polymeric nanoparticle (PNP) formulation development requires trial-and-error experimentation to meet the target product profile, which is laborious and costly. Herein, we design a preformulation framework (solid-state screening, computational approach, and solubility in PNP-forming emulsion) to understand counterion-drug-polymer interactions and accelerate the PNP formulation development for HIP systems. The HIP interactions between a small hydrophilic molecule, AZD2811, and counterions with different molecular structures were investigated. Cyclic counterions formed amorphous ion pairs with AZD2811; the 0.7 pamoic acid/1.0 AZD2811 complex had the highest glass transition temperature (T_g; 162 °C) and the greatest drug loading (22%) and remained as phase-separated amorphous nanosized domains inside the polymer matrix. Palmitic acid (linear counterion) showed negligible interactions with AZD2811 (crystalline-free drug/counterion forms), leading to a significantly lower drug loading despite having similar log P and pK_a with pamoic acid. Computational calculations illustrated that cyclic counterions interact more strongly with AZD2811 than linear counterions through dispersive interactions (offset π-π interactions). Solubility data indicated that the pamoic acid/AZD2811 complex has a lower organic phase solubility than AZD2811-free base; hence, it may be expected to precipitate more rapidly in the nanodroplets, thus increasing drug loading. Our work provides a generalizable preformulation framework, complementing traditional performance-indicating parameters, to identify optimal counterions rapidly and accelerate the development of hydrophilic drug PNP formulations while achieving high drug loading without laborious trial-and-error experimentation.

Non-spherical Polymeric Nanocarriers for Therapeutics: The Effect of Shape on Biological Systems and Drug Delivery Properties

This review aims to highlight the importance of particle shape in the design of polymeric nanocarriers for drug delivery systems, along with their size, surface chemistry, density, and rigidity. Current manufacturing methods used to obtain non-spherical polymeric nanocarriers such as filomicelles or nanoworms, nanorods and nanodisks, are firstly described. Then, their interactions with biological barriers are presented, including how shape affects nanoparticle clearance, their biodistribution and targeting. Finally, their drug delivery properties and their therapeutic efficacy, both in vitro and in vivo, are discussed and compared with the characteristics of their spherical counterparts.

Nanoparticles Loaded with Docetaxel and Resveratrol as an Advanced Tool for Cancer Therapy

A growing interest in the use of a combination of chemosensitizers and cytostatics for overcoming cancer resistance to treatment and the development of their delivery systems has been observed. Resveratrol (Res) presents antioxidant, anti-inflammatory and chemopreventive properties but also limits multidrug resistance against docetaxel (Dtx), which is one of the main causes of failure in cancer therapy with this drug. However, the use of both drugs presents challenges, including poor bioavailability, the unfavourable pharmacokinetics and chemical instability of Res and the poor water solubility and dose-limiting toxicity of Dtx. In order to overcome these difficulties, attempts have been made to create different forms of delivery for both agents. This review is focused on the latest developments in nanoparticles for the delivery of Dtx, Res and for the combined delivery of those two drugs. The aim of this review was also to summarize the synergistic mechanism of action of Dtx and Res on cancer cells. According to recent reports, Dtx and Res loaded in a nano-delivery system exhibit better efficiency in cancer treatment compared to free drugs. Also, the co-delivery of Dtx and Res in one actively targeted delivery system providing the simultaneous release of both drugs in cancer cells has a chance to fulfil the requirements of effective anticancer therapy and reduce limitations in therapy caused by multidrug resistance (MDR).

Chitosan-based DDSs for pH/hypoxia dual-triggered DOX delivery: Facile morphology modulation for higher in vitro cytotoxicity

The morphology of the drug delivery systems (DDSs) has been recognized to play an important role in their phagocytosis, cellular interaction and distribution. However, it is a technical challenge to simply prepare the non-spherical nanoscaled DDSs. Here, a facile strategy was developed to fabricate the pH/hypoxia dual-responsive nanowires by adding the maleic acid (MAH) and PEG modified chitosan (PEG-SS-CS-MAH) into aqueous solution of DOX. Compared with the PEG-SS-CS-MAH/DOX nanoparticles (NPs) by adding DOX into the PEG-SS-CS-MAH solution, the PEG-SS-CS-MAH/DOX nanowires (NWs) possessed a higher drug loading capacity of 58% and better pH/hypoxia dual-triggered DOX release performance with higher drug release in the simulated tumor intracellular microenvironment but a much lower premature drug leakage in the simulated normal physiological medium. As a result, higher in vitro anti-tumor efficacy was achieved with the PEG-SS-CS-MAH/DOX NWs, demonstrating their promising potential for tumor chemotherapy.

Comparison of PLA-Based Micelles and Microspheres as Carriers of Epothilone B and Rapamycin. The Effect of Delivery System and Polymer Composition on Drug Release and Cytotoxicity against MDA-MB-231 Breast Cancer Cells

Co-delivery of epothilone B (EpoB) and rapamycin (Rap) increases cytotoxicity against various kinds of cancers. However, the current challenge is to develop a drug delivery system (DDS) for the simultaneous delivery and release of these two drugs. Additionally, it is important to understand the release mechanism, as well as the factors that affect drug release, in order to tailor this process. The aim of this study was to analyze PLA–PEG micelles along with several types of microspheres obtained from PLA or a mixture of PLA and PLA–PEG as carriers of EpoB and Rap for their drug release properties and cytotoxicity against breast cancer cells. The study showed that the release process of EpoB and Rap from a PLA-based injectable delivery systems depends on the type of DDS, morphology, and polymeric composition (PLA to PLA–PEG ratio). These factors also affect the biological activity of the DDS, because the cytotoxic effect of the drugs against MDA-MB-231 cells depends on the release rate. The release process from all kinds of DDS was well-characterized by the Peppas–Sahlin model and was mainly controlled by Fickian diffusion. The conducted analysis allowed also for the selection of PLA 50/PLA–PEG 50 microspheres and PLA–PEG micelles as a promising co-delivery system of EpoB and Rap.

Hydrophilicity Affecting the Enzyme-Driven Degradation of Piezoelectric Poly-l-Lactide Films

Biocompatible and biodegradable poly-l-lactic acid (PLLA) processed into piezoelectric structures has good potential for use in medical applications, particularly for promoting cellular growth during electrostimulation. Significant advantages like closer contacts between cells and films are predicted when their surfaces are modified to make them more hydrophilic. However, there is an open question about whether the surface modification will affect the degradation process and how the films will be changed as a result. For the first time, we demonstrate that improving the polymer surface’s wettability affects the position of enzyme-driven degradation. Although it is generally considered that proteinase K degrades only the polymer surface, we observed the enzyme’s ability to induce both surface and bulk degradation. In hydrophilic films, degradation occurs at the surface, inducing surface erosion, while for hydrophobic films, it is located inside the films, inducing bulk erosion. Accordingly, changes in the structural, morphological, mechanical, thermal and wetting properties of the film resulting from degradation vary, depending on the film’s wettability. Most importantly, the degradation is gradual, so the mechanical and piezoelectric properties are retained during the degradation.

Elongated self-assembled nanocarriers: From molecular organization to therapeutic applications

Self-assembled cylindrical aggregates made of amphiphilic molecules emerged almost 40 years ago. Due to their length up to micrometers, those particles display original physico-chemical properties such as important flexibility and, for concentrated samples, a high viscoelasticity making them suitable for a wide range of industrial applications. However, a quarter of century was needed to successfully take advantage of those improvements towards therapeutic purposes. Since then, a wide diversity of biocompatible materials such as polymers, lipids or peptides, have been developed to design self-assembling elongated drug nanocarriers, suitable for therapeutic or diagnostic applications. More recently, the investigation of the main forces driving the unidirectional growth of these nanodevices allowed a translation toward the formation of pure nanodrugs to avoid the use of unnecessary side materials and the possible toxicity concerns associated.

Poly (ethylene glycol)-block-poly (D, L-lactide) (PEG-PLA) micelles for brain delivery of baicalein through nasal route for potential treatment of neurodegenerative diseases due to oxidative stress and inflammation: An in vitro and in vivo study

The application of baicalein (BE) in central nervous system (CNS) neurodegenerative diseases is hampered by its poor solubility and low oral bioavailability despite its neuroprotective effects. In this study, BE was encapsulated into poly (ethylene glycol)-block-poly (D, L-lactide) micelles (BE-MC) and administrated through nasal inhalation to enhance its brain distribution. BE-MC showed comparable in-vitro antioxidant activity to BE solution. Cytotoxicity study illustrated BE-MC could reduce BE's toxicity in SH-SY5Y cells and BV-2 cells. BE solution at concentration higher than 5 µM caused significant BV-2 cells' death after stimulation of LPS while BE-MC were non-toxic to cells at concentrations up to 50 µM. BE solution at 5 µM had no anti-inflammatory effects in BV-2 cells while BE-MC could reduce the inflammatory factor TNF-α at 5 µM and IL-6 at 20 µM significantly. Pharmacokinetic studies in C57BL/6 mice showed the absolute AUC values of BE in plasma and brain of BE-MC through nasal inhalation group were 5.09-fold and 1.50-fold higher than that of BE coarse powder through oral administration group at the same dose. Thus, our study indicated BE-MC administered nasally could be useful for treatment of CNS neurodegenerative diseases due to oxidative stress and inflammation.

Screening and Matching Polymers with Drugs to Improve Drug Incorporation and Retention in Nanoparticles

Key challenges hindering the clinical translation of the use of nanoparticles (NP) for delivery of drugs to tumors are inadequate drug loading and premature drug release. This study focused on understanding the conditions required to produce nanoparticles that can reach their target site with sufficient drug loading and drug retention for effective pharmacological action. Etoposide, etoposide phosphate, and teniposide were screened against modified poly(glycerol) adipate (PGA) based polymers by monitoring drug release from 40% drug in polymer films and using Fourier transform infrared spectroscopy (FTIR) and contact angle measurements to help understand the release results. Polymers were matched with the specific drugs based on the interactions observed. NP were then prepared by an interfacial deposition method. NPs were characterized and resulted in drug loadings ranging from 3.5% and 5%, respectively, for etoposide phosphate and etoposide with PGA modified with stearate (PGA85%C18) up to 13.4% for teniposide with PGA modified with tryptophan (PGA50%Try) and drug release of just 22-35% over 24 h. Assessment of cytotoxicity showed that etoposide nanoparticles with PGA85%C18 were more potent than an equivalent amount of free drug. This screening method to match polymers to drugs to monitor based drug and polymer interactions thus resulted in the formulation of nanoparticles with higher drug loading and slower release and potential for further development for clinical applications.

Experimental Tests, FEM Constitutive Modeling and Validation of PLGA Bioresorbable Polymer for Stent Applications

The use of bioresorbable polymers such as poly(lactic-co-glycolic acid) (PLGA) in coronary stents can hypothetically reduce the risk of complications (e.g., restenosis, thrombosis) after percutaneous coronary intervention. However, there is a need for a constitutive modeling strategy that combines the simplicity of implementation with strain rate dependency. Here, a constitutive modeling methodology for PLGA comprising numerical simulation using a finite element method is presented. First, the methodology and results of PLGA experimental tests are presented, with a focus on tension tests of tubular-type specimens with different strain rates. Subsequently, the constitutive modeling methodology is proposed and described. Material model constants are determined based on the results of the experimental tests. Finally, the developed methodology is validated by experimental and numerical comparisons of stent free compression tests with various compression speeds. The validation results show acceptable correlation in terms of both quality and quantity. The proposed and validated constitutive modeling approach for the bioresorbable polymer provides a useful tool for the design and evaluation of bioresorbable stents.

Wormlike Nanovector with Enhanced Drug Loading Using Blends of Biodegradable Block Copolymers

The application of nanoparticles comprising amphiphilic block copolymers for the delivery of drugs is a subject of great interest as they hold promise for more effective and selective therapies. In order to achieve this ambition, it is of critical importance to develop our understanding of the self-assembly mechanisms by which block copolymers undergo so that we can control their morphology, tune their ability to be loaded with biofunctional cargoes, and optimize their interactions with target cells. To this end, we have developed a strategy by which blends of (biocompatible) amphiphilic block copolymers generate nonspherical nanovectors, simultaneously enhancing drug loading without the need for subsequent purification owing to the use of the biocompatible direct hydration approach. The principal morphology achieved using this blending strategy are wormlike nanovectors (nanoworms, NWs), with an elongated form known to have a profound effect on flow behavior and interactions with cells. Unloaded nanoworms are not toxic toward human retinal (ARPE-19) cells and can be effectively endocytosed even after varying the surface charge. In terms of drug loading, we demonstrate that uptake of dexamethasone (DEX; a clinically relevant therapeutic agent) in nanoworms (DEX@NWs) can be enhanced using this process, increasing drug content up to 0.5 mg/mL (10 wt % in particles). Furthermore, such nanoworms are stable for at least 5 months and are, therefore, a promising platform for nanomedicine applications.

Biocompatibility and paclitaxel/cisplatin dual-loading of nanotubes prepared from poly(ethylene glycol)-polylactide-poly(ethylene glycol) triblock copolymers for combination cancer therapy

Nanotubes were prepared by self-assembly of the copolymer using co-solvent evaporation method. The biocompatibility of the nanotubes was assessed in comparison with spherical micelles and filomicelles prepared from poly(ethylene glycol)-poly(L-lactide-co-glycolide) (PEG-PLGA) and poly(ethylene glycol)-poly(L-lactide) (PEG-PLA), respectively. Several aspects of biocompatibility of the aggregates were considered, including agar diffusion and MTT assay, release of cytokines, hemolysis, protein adsorption, dynamic clotting in vitro, and Zebrafish embryonic compatibility in vivo. The nanotubes present good cell compatibility and blood compatibility in vitro, and almost no toxicity towards Zebrafish embryos development in vivo. Furthermore, dual-loading of hydrophilic cisplatin and hydrophobic paclitaxel was achieved in the nanotubes with high loading content and loading efficiency. The release of both drugs was slower from dual-loaded nanotubes than from single-loaded ones, but the total amount of released drugs in higher for dual-loaded nanotubes than from single-loaded ones. Cellular uptake and inhibition tests showed that the nanotubes were successfully taken up by tumor cells and effectively inhibited cell growth. It is thus concluded that PEG-PLA-PEG nanotubes with outstanding biocompatibility could be promising for co-delivery of hydrophilic and hydrophobic agents in combination cancer therapy.

pH/redox dual-responsive amphiphilic zwitterionic polymers with a precisely controlled structure as anti-cancer drug carriers

Responding to the tumor microenvironment, functional polymers can serve as preeminent drug carriers for targeted cancer therapy. Stimuli-responsive polymeric drug carriers are reported with diverse anti-tumor effects for various polymer structures. Thus, three pH/redox dual-responsive amphiphilic zwitterionic polymer 'isomers' with different locations of pH/redox responsive units were prepared to understand the relationship between polymer structure and anti-tumor effect. Containing poly(ε-caprolactone) (PCL), poly(N,N-diethylaminoethyl methacrylate) (PDEA) and poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC), polymers PCL-ss-P(DEA-r-MPC) (SDRM), PCL-ss-PDEA-b-PMPC (SDBM) and PCL-PDEA-ss-PMPC (DSM) with a precisely controlled structure were constructed and confirmed through NMR, FITR and EA. The formed micellar drug carriers were characterized by their morphology, loading capacity, acid/redox sensitivity, drug release, in vitro cytotoxicity and in vivo antitumor effects. Micelles with uniform spherical morphologies can effectively encapsulate anti-tumor drugs such as DOX. Among these micelles, DSM@DOX displays the most excellent drug encapsulation capacity (13.4%) with neutral surface charge (-1.02 mV) and good stability, and is different from SDRM@DOX with positive charge (+11.1 mV) and SDBM@DOX with poor stability. All micelles respond to acid and reducing environments and present fast drug release at mildly acidic pH and high concentrations of GSH, exhibiting low burst release under the physiological conditions of plasma. There is no significant difference between these micelles in tumor cell cytotoxicity against MCF-7 and 4T1 cells. Internalization of SDRM@DOX and DSM@DOX by the tumor cells is stronger than that of SDBM@DOX. Notably, DSM@DOX has longer blood circulation and more effective accumulation at the tumor site than the other two micelles. As a result, DSM@DOX shows enhanced antitumor efficacy in 4T1 tumor-bearing mice with reduced side toxicities. Overall, structures of the above polymers significantly influence the in vivo antitumor effects of the drug carriers through blood circulation and cellular uptake.

Cytotoxic Effect of Paclitaxel and Lapatinib Co-Delivered in Polylactide-co-Poly(ethylene glycol) Micelles on HER-2-Negative Breast Cancer Cells

To find better strategies to enhance the cytotoxic effect of paclitaxel (PTX) and lapatinib (LAP) against breast cancer cells, we analyzed the efficacy of a novel delivery system containing polylactide-co-poly(ethylene glycol) (PLA-PEG) filomicelles of over 100 nm in length and spherical micelles of approximately 20 nm in diameter. The ¹H NMR measurements confirmed the incorporation of PTX and LAP into micelles. Analysis of the drug release mechanism revealed the diffusion-controlled release of LAP and anomalous transport of PTX. Drug content analysis in lyophilized micelles and micellar solution showed their good storage stability for at least 6 weeks. Blank micelles, LAP-loaded micelles and free LAP did not affect MCF-7 breast cancer cell proliferation, suggesting that the cytotoxicity of PTX-, PTX/LAP-loaded micelles, and the binary mixture of free PTX and LAP was solely caused by PTX. PTX/LAP-loaded micelles showed greater toxicity compared to the binary mixture of PTX and LAP after 48 h and 72 h. Only free PTX alone induced P-gp activity. This study showed the feasibility of using a LAP and PTX combination to overcome MDR in MCF-7 cells, particularly when co-loaded into micelles. We suggest that PTX/LAP micelles can be applicable not only for the therapy of HER-2-positive, but also HER-2-negative breast cancers.

Bioresorbable filomicelles for targeted delivery of betulin derivative - In vitro study

Filomicelles (worm-like micelles) possess high drug loading capacity and long circulation time in the bloodstream. A novel approach can be filomicelles with folic acid (FA) as a targeting moiety. Folate-drug delivery systems can target FA receptors (FAR) that are overexpressed in several human carcinomas, which can potentially maximize therapeutic efficacy while minimizing side effects. The aim of this study was to develop filomicelles from combination of poly(L-lactide)-Jeffamine-folic acid and poly(L-lactide)-poly(ethylene glycol) for delivery of betulin derivative. Phosphate derivative of betulin reveals high cytotoxicity against cancer cells, however its application is restricted due to poor solubility in water. Incorporation into hydrophobic core of micelles can effectively solubilize the drug. Three kinds of micelles were obtained with high drug loading capacity. Based on TEM analysis, the copolymers formed exclusively filomicelles or mixture of filomicelles and spherical micelles. All kinds of micelles provided release of betulin derivative for over 9 days and apart the very initial phase displayed similar release profile. The influence of PLA block on initial burst effect was revealed. The in vitro cytotoxicity of betulin derivative loaded micelles against FAR-positive HeLa cells was confirmed, which proves their usefulness for targeted delivery of cytostatic drug.

Encapsulation of the HSP-90 Chaperone Inhibitor 17-AAG in Stable Liposome Allow Increasing the Therapeutic Index as Assessed, in vitro, on Leishmania (L) amazonensis Amastigotes-Hosted in Mouse CBA Macrophages

The current long-term treatment for leishmaniasis causes severe side effects and resistance in some cases. An evaluation of the anti-leishmanial potential of an HSP90-inhibitor, 17-allylamino-17-demethoxygeldanamycin (17-AAG), demonstrated its potent effect against Leishmania spp. in vitro and in vivo. We have previously shown that 17-AAG can kill L. (L) amazonensis promastigotes with an IC₅₀ of 65 nM and intracellular amastigote at concentrations as low as 125 nM. As this compound presents low solubility and high toxicity in human clinical trials, we prepared an inclusion complex containing hydroxypropyl-β-cyclodextrin and 17-AAG (17-AAG:HPβCD) to improve its solubility. This complex was characterized by scanning electron microscopy, and X-ray diffraction. Liposomes-containing 17-AAG:HPβCD was prepared and evaluated for encapsulation efficiency (EE%), particle size, polydispersity index (PDI), pH, and zeta potential, before and after accelerated and long-term stability testing. An evaluation of leishmanicidal activity against promastigotes and intracellular amastigotes of L. (L) amazonensis was also performed. The characterization techniques utilized confirmed the formation of the inclusion complex, HPβCD:17-AAG, with a resulting 33-fold-enhancement in compound water solubility. Stability studies revealed that 17-AAG:HPβCD-loaded liposomes were smaller than 200 nm, with 99% EE. Stability testing detected no alterations in PDI that was 0.295, pH 7.63, and zeta potential +22.6, suggesting liposome stability, and suitability for evaluating leishmanicidal activity. Treatment of infected macrophages with 0.006 nM of 17-AAG:HPβCD or 17-AAG:HPβCD-loaded liposomes resulted in almost complete amastigote clearance inside macrophages after 48 h. This reduction is similar to the one observed in infected macrophages treated with 2 μM amphotericin B. Our results showed that nanotechnology and drug delivery systems could be used to increase the antileishmanial efficacy and potency of 17-AAG in vitro, while also resulting in reduced toxicity that indicates these formulations may represent a potential therapeutic strategy against leishmaniasis.

Improving the pharmacokinetics and tissue distribution of pyrinezolid by self-assembled polymeric micelles

Antibiotic-resistance by bacteria is a growing global concern within the healthcare field, and it has provided an impetus for continued antimicrobial development. Pyrinezolid (PZ), a novel oxazolidinone compound, can effectively inhibit most gram-positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococci (VRE). Though PZ is a promising antimicrobial candidate, the druggability of PZ is limited by its poor water solubility. Therefore, the amphipathic mPEG-PLLA copolymer was used to prepare the pyrinezolid micelles (PZ-M). Herein, we described the preparation, pharmacokinetic properties, tissue distribution, efficacy and toxicity of PZ-M. In vivo studies show that PZ-M possess prolonged blood circulation time and increased oral bioavailability compared with free PZ. Meanwhile, PZ-M increase lung PZ exposure and reduce liver and kidney exposure, which indicates that PZ-M may enhance the efficacy in vivo in MRSA-related pneumonia patients and decrease potential renal and hepatic toxicities.

Mixed poly(vinyl pyrrolidone)-based drug-loaded nanomicelles shows enhanced efficacy against pancreatic cancer cell lines

We report in this paper on the enhanced efficacy of a physical mixture of two single anti-cancer loaded nanomicelles against PANC-1 and BxPC-3. Poly(vinyl pyrrolidone-b-polycaprolactone) (PVP-b-PCL) and poly(vinyl pyrrolidone-b-poly(dioxanone-co-methyl dioxanone)) (PVP-b-P(DX-co-MeDX)) were synthesized and successfully loaded with various anti-cancer drugs - gemcitabine (GEM), doxorubicin.HCl (DOX.HCl), doxorubicin.NH₂ (DOX), 5-fluorouracil (5-FU) and paclitaxel (PTX). Spherical micelles of size 160-477 nm were obtained as characterized by DLS while sizes determined by TEM were in the range 140-250 nm. The hydrophobic drugs had a higher loading percentage efficiency compared to hydrophilic drugs in the trend PTX>DOX>5-FU>GEM>DOX.HCl whereas the drug release pattern followed the reverse trend in accordance with decreased polymer-drug interaction as quantified by the binding constant and micellar drug location. Cellular uptake studies showed that nanomicelles are taken up by pancreatic cancer cells into the cytoplasm and nucleus. The free nanomicelles were confirmed to be non-cytotoxic. A physical mixture of GEM loaded micelles and DOX.HCl loaded micelles of comparable size showed significantly higher cytotoxicity than either the free drug mixture or the individual single drug loaded micelles as confirmed by their IC₅₀ values.