Nanoscale Lipophilic Prodrugs of Dexamethasone with Enhanced Pharmacokinetics

Robust micelles formulation to improve systemic corticosteroid therapy in sepsis in multiple healthcare systems

Sepsis is a life-threatening condition resulting from an imbalanced immune response to an infection that causes over 10 million deaths annually, particularly in low and middle-income countries. Current clinical management of sepsis relies on infection control, homeostasis restoration, and systemic corticosteroid therapy. Unfortunately, while beneficial, corticosteroid regimens, including dexamethasone, can lead to adverse effects such as neurological and metabolic complications, limiting their use. In this work, we decided to develop a scalable production method using only approved and cost-effective materials. We also conceived our formulation to be freeze-drying friendly to allow its use within various healthcare systems. Following those concepts, we designed DSPE-PEG(2000)-based micelles to encapsulate dexamethasone, and improve its in vivo efficacy by extending blood circulation time and targeting innate blood immune cells. First, the physicochemical properties, stability, in vitro release kinetics, and efficacy of dexamethasone-loaded micelles were comprehensively measured to demonstrate the platform's robustness. The therapeutic in vivo efficacy of dexamethasone-loaded micelles and their ability to increase animal survival was exhibited in two murine sepsis models, an endotoxemia model, and the cecal ligation and puncture model. Various biodistribution and ex vivo fluorescence imaging assays revealed that using micelles led to an improved blood circulation time and a preferential accumulation within immune cells that could explain the enhanced efficacy of dexamethasone-loaded micelles compared to the soluble form of the drug used clinically. Altogether, our results indicate that this robust micellar delivery system can potentially improve the anti-inflammatory therapy of dexamethasone, offering a safer and more effective alternative to conventional corticosteroid regimens in sepsis.

Modulation of photoacoustic NIR BODIPY self-assembly in theranostic solid lipid nanoparticles via alpha-group variation: influence on spectral and nanostructural properties

Loading drug nanovectors with a high quantity of near-infrared organic dye considerably increases their absorption cross-section and favors their detection as theranostic agents with photoacoustic imaging. In a previous study, solid lipid nanoparticles (SLNs) of dexamethasone palmitate were labeled with BODIPY-aniline-palmitate and revealed exquisite photoacoustic properties: a NIR absorption cross-section comparable to gold nanoparticles and a photoacoustic generation efficiency above 1. However, strong and gradual spectral modifications were observed with the increasing dye concentration. The spectral transformations were linked to dye aggregation in the SLNs, and potential further transformations occuring after in vivo injection may hinder longitudinal imaging applications. In the present study, we introduce BODIPY-julolidine-palmitate, a second dye able to label the SLNs, but without any marked aggregation behaviour. We perform a comparative study of labelled SLNs in various matching concentrations of each dye in terms of optical and photoacoustic properties, showing lower modifications of the spectral behaviour with the dye concentration for BODIPY-judolidine and establishing the influence of the lipid core on the photoacoustic generation efficiency regardless of the dye. Cryo-EM and SAXS-WAXS studies reveal a lamellar arrangement at the nanoscale for SLNs labelled with a high concentration of BODIPY-aniline whereas SLNs labelled with BODIPY-julolidine display an amorphous structure. Overall, BODIPY-julolidine-palmitate at moderate label concentration appears a better candidate to label SLNs for theranostic applications using photoacoustic imaging.

Rationale and design for the thoracic Paravertebral Adjunctive Dexamethasone Palmitate Reducing chronic pain After cardiac surgery (PANDORA) trial: a parallel-group, double-blinded, randomised controlled, single-centre study

INTRODUCTION

Minimally invasive cardiac surgery (MICS) is important for enhanced recovery in cardiac surgery. However, the incidence of chronic postsurgical pain (CPSP) is high and is associated with worsened quality of recovery and life, as well as raised short-term or long-term mortality. The mechanism is not clear, and there is still a lack of safe and effective preventive measures.

METHODS AND ANALYSIS

The Paravertebral Adjunctive Dexamethasone Palmitate Reducing chronic pain After cardiac surgery (PANDORA) trial is a parallel-group, double-blinded, randomised controlled, single-centre study recruiting 902 participants undergoing MICS. Participants will be randomised in a 1:1 ratio to dexamethasone palmitate (D-PAL) emulsion group and dexamethasone (DSP) group. To investigate the effect of a single bolus perineural administration of D-PAL as an adjuvant treatment to a standard thoracic paravertebral block (TPVB) with ropivacaine decreases the incidence of CPSP in adult patients as compared with single bolus perineural administration of DSP combined with ropivacaine in TPVB. The primary endpoint is the incidence of chronic postoperative pain at 3 months following surgery defined as per the updated International Classification of Diseases. CPSP is defined as a new development of pain or increase in the intensity of pain at the surgical area or projected onto the innervation area of a nerve in this area after a surgical procedure that persists for at least 3 months. The nature and intensity of pain will be evaluated with a Brief Pain Inventory Short Form (BPI-SF) questionnaire.

ETHICS AND DISSEMINATION

The trial was approved by the Ethics Committee of Xijing Hospital, the First Affiliated Hospital of Air Force Military Medical University (KY20232194-C-1). Results will be submitted for publication in peer-reviewed journals and presented at academic meetings.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov, NCT05920967.

Quantitative photoacoustic spectral transformations in theranostic solid lipid nanoparticles labelled with increasing concentrations of a photoacoustic NIR BODIPY

Solid lipid nanoparticles (SLNs) have shown great capabilities for drug delivery and are therefore attractive theranostic candidates when labelled with an imaging contrast agent. This work aims to create the first SLNs labelled for photoacoustic (PA) imaging by encapsulating a specially designed and near-infrared absorbing BODIPY dye (BY-aniline-Palm) into SLNs of dexamethasone palmitate. A one-pot formulation protocol enabled us to replace the prodrug with the BY-aniline-Palm label in various proportions up to 100%. Increasing the dye content resulted in complex but gradual transformations of the SLNs in terms of optical absorption and PA spectra, and the formation of aggregates at high concentration. A comprehensive and quantitative PA spectrometric study revealed a photoacoustic generation efficiency (PGE) that was spectrally varying and notably greater than 1. A joint spectral decomposition of the absorption and PA spectra into the sum of three Gaussian functions displayed a per-band evolution of the PGE when the concentration of BY-aniline-Palm varied and showed an interplay between the bands with a constant spectrum area. Finally, a novel quantitative PA spectroscopic approach, involving measurements at three different ambient temperatures, demonstrated that the remarkable PGE values arose from a significant thermo-elastic expansion of the SLNs during PA signal generation independently of the absorption band. This study highlights that labeled SLNs are promising agents for PA imaging and also unveils complex transformations that can occur in such nanosystems with a dye prone to aggregation.

Solid Lipid Nanoparticles Loaded with Dexamethasone Palmitate for Pulmonary Inflammation Treatment by Nebulization Approach

Pneumonia stands as the leading infectious cause of childhood mortality annually, underscoring its significant impact on pediatric health. Although dexamethasone (DXMS) is effective for treating pulmonary inflammation, its therapeutic potential is compromised by systemic side effects and suboptimal carrier systems. To address this issue, the current study introduces solid lipid nanoparticles encapsulating hydrophobic dexamethasone palmitate (DXMS-Pal-SLNs) as an anti-inflammatory nanoplatform to treat pneumonia. The specialized nanoparticle formulation is characterized by high drug loading efficiency, low drug leakage and excellent colloidal stability in particular during nebulization and is proficiently designed to target alveolar macrophages in deep lung regions via local delivery with the nebulization administration. In vitro analyses revealed substantial reductions in the secretions of tumor necrosis factor-α and interleukin-6 from alveolar macrophages, highlighting the potential efficacy of DXMS-Pal-SLNs in alleviating pneumonia-related inflammation. Similarly, in vivo experiments showed a significant reduction in the levels of these cytokines in the lungs of mice experiencing lipopolysaccharide-induced pulmonary inflammation after the administration of DXMS-Pal-SLNs via nebulization. Furthermore, the study demonstrated that DXMS-Pal-SLNs effectively control acute infections without causing pulmonary infiltration or excessive recruitment of immunocytes in lung tissues. These findings highlight the potential of nebulized DXMS-Pal-SLNs as a promising therapeutic strategy for mitigating pneumonia-related inflammations.

Glucocorticoids-based prodrug design: Current strategies and research progress

Attributing to their broad pharmacological effects encompassing anti-inflammation, antitoxin, and immunosuppression, glucocorticoids (GCs) are extensively utilized in the clinic for the treatment of diverse diseases such as lupus erythematosus, nephritis, arthritis, ulcerative colitis, asthma, keratitis, macular edema, and leukemia. However, long-term use often causes undesirable side effects, including metabolic disorders-induced Cushing's syndrome (buffalo back, full moon face, hyperglycemia, etc.), osteoporosis, aggravated infection, psychosis, glaucoma, and cataract. These notorious side effects seriously compromise patients' quality of life, especially in patients with chronic diseases. Therefore, glucocorticoid-based advanced drug delivery systems for reducing adverse effects have received extensive attention. Among them, prodrugs have the advantages of low investment, low risk, and high success rate, making them a promising strategy. In this review, we propose the strategies for the design and summarize current research progress of glucocorticoid-based prodrugs in recent decades, including polymer-based prodrugs, dendrimer-based prodrugs, antibody-drug conjugates, peptide-drug conjugates, carbohydrate-based prodrugs, aliphatic acid-based prodrugs and so on. Besides, we also raise issues that need to be focused on during the development of glucocorticoid-based prodrugs. This review is expected to be helpful for the research and development of novel GCs and prodrugs.

Diclofenac prodrugs nanoparticles: An alternative and efficient treatment for rheumatoid arthritis?

We have synthesized new lipidic prodrugs of diclofenac by grafting aliphatic chains (C10, C12, C16 and C18) to diclofenac through an ester bond. Their molecular formulas were confirmed through HR-MS and the formation of ester bond by FTIR and NMR spectroscopy. Nanoparticles of the different prodrugs were successfully formulated using emulsion evaporation method and DSPE-PEG2000 as the only excipient. All nanoparticles were spherical and had a size between 110 and 150 nm, PdI ≤ 0.2 and negative Zeta potential values from -30 to -50 mV. In addition, they were stable upon storage at 4 °C up to 30-35 days. The encapsulation efficiency of the prodrug was above 90 % independently of the aliphatic chain length grafted. Nanoparticles did not induce any toxicity on LPS-activated THP-1 cells up to a concentration of 100 μg/mL (equivalent diclofenac) whereas diclofenac sodium salt IC50 was around 20 μg/mL. Following incubation of nanoparticles with LPS-activated THP-1 cells, a dose dependent inhibition of TNF-α was observed comparable to standard diclofenac sodium. Based on in vitro studies representative nanoparticles, Prodrug 3 NPs (C16 aliphatic chain) were selected for further in vitro and in vivo studies. Upon incubation in murine plasma, Prodrug 3 NPs underwent an enzymatic cleavage and almost 70 % of diclofenac was released from nanoparticles in 8 h. In vivo studies on a collagen induced arthritis murine model showed contrasted results: on one hand Prodrug 3 NPs led to a significant decrease of arthritis score and of paw volume compared to PBS after the second injection, on the other hand the third injection induced an important hepatic toxicity with the death of half of the mice from the NP group. To promote the reduction of inflammation while avoiding hepatic toxicity using NPs would require to precisely study the No Observable Adverse Effect Level and the schedule of administration in the future.

Modulation of release and pharmacokinetics from nanoscale lipid prodrugs of dexamethasone with variable linkage chemistry

In an attempt to tune drug release and subsequent pharmacokinetics once administered intravenously, we have synthesized three lipid-drug conjugates (LDCs) of dexamethasone (DXM) each possessing a different lipid-drug chemical linkage: namely ester, carbamate and carbonate. These LDCs were thoroughly characterized before being turned into nanoscale particles by an emulsion-evaporation process using DSPE-PEG2000 (Distearoyl-sn-Glycero-3-Phosphoethanolamine-N-(methoxy(polyethylene glycol)-2000) as the only excipient. Spherical nanoparticles (NPs) of about 140-170 nm, with a negative zeta potential, were obtained for each LDC and exhibited good stability upon storage at 4 °C for 45 days with no recrystallization of LDCs observed. LDC encapsulation efficacy was above 95% for the three LDCs, leading to a LDC loading of about 90% and an equivalent DXM loading above 50%. Although the ester and carbonate NPs did not exhibit any toxicity up to an equivalent DXM concentration of 100 μg/mL, the carbamate LDC NPs appeared very toxic towards RAW 264.7 macrophages and were discarded. Both ester and carbonate LDC NPs were shown to exert anti-inflammatory activity on LPS-activated macrophages. DXM release from LDC NPs in murine plasma was faster from ester than from carbonate NPs. Finally, pharmacokinetics and biodistribution were conducted, showing a lower exposure to DXM from carbonate LDC NPs than from ester LDC NPs, correlated with the slower DXM release from carbonate LDC NPs. These results outline the need for extended studies to find the best prodrug system for extended drug release.

Non-aqueous formulations in topical ocular drug delivery - a paradigm shift?

Topical eyedrop application is the preferred route for drug delivery to anterior segment tissues; however, the challenge of overcoming the eye's anatomical and physiological barriers while minimising tissue toxicity has restricted developments in this field. Aqueous vehicles have traditionally been used, which typically require several additives and preservatives to achieve physiologically compatible and sterile eyedrops, elevating their toxicity potential. Non-aqueous vehicles have been suggested as efficient alternatives for topical drug delivery as they can address many of the limitations associated with conventional aqueous eyedrops. However, despite their obvious advantages, non-aqueous eyedrops remain poorly researched and few non-aqueous formulations are currently available in the market. This review challenges the conventional hypothesis that aqueous solubility is a prerequisite to ocular drug absorption and establishes a rationale for using non-aqueous vehicles for ocular drug delivery. Recent advances in the field have been detailed and future research prospects have been explored, pointing towards a paradigm shift in eyedrop formulation in the near future.

Enhancing Methotrexate Delivery in the Brain by Mesoporous Silica Nanoparticles Functionalized with Cell-Penetrating Peptide using in Vivo and ex Vivo Monitoring

The blood-brain barrier (BBB) acts as a physical/biochemical barrier that protects brain parenchyma from potential hazards exerted by different xenobiotics found in the systemic circulation. This barrier is created by "a lipophilic gate" as well as a series of highly organized influx/efflux mechanisms. The BBB bottleneck adversely affects the efficacy of chemotherapeutic agents in treating different CNS malignancies such as glioblastoma, an aggressive type of cancer affecting the brain. In the present study, mesoporous silica nanoparticles (MSNs) were conjugated with the transactivator of transcription (TAT) peptide, a cell-penetrating peptide, to produce MSN-NH-TAT with the aim of improving methotrexate (MTX) penetration into the brain. The TAT-modified nanosystem was characterized by Fourier transform infrared spectrometry (FTIR), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), dynamic light scattering (DLS), and N₂ adsorption-desorption analysis. In vitro hemolysis and cell viability studies confirmed the biocompatibility of the MSN-based nanocarriers. In addition, in vivo studies showed that the MTX-loaded MSN-NH-TAT improved brain-to-plasma concentration ratio, brain uptake clearance, and the drug's blood terminal half-life, compared with the use of free MTX. Taken together, the results of the present study indicate that MSN functionalization with TAT is crucial for delivery of MTX into the brain. The present nanosystem represents a promising alternative drug carrier to deliver MTX into the brain via overcoming the BBB.

Amphiphilic Phosphorus Dendrons Associated with Anti-inflammatory siRNA Reduce Symptoms in Murine Collagen-Induced Arthritis

Small interfering RNA (siRNA) holds promise for treating rheumatoid arthritis by inhibiting major cytokines such as tumor necrosis factor-α (TNF-α). We developed original cationic amphiphilic phosphorus dendrons to produce dendriplexes associated with TNF-α siRNA. The dendrons were made of 10 pyrrolidinium end groups and a C17 aliphatic chain. The dendriplexes demonstrated the ability to protect siRNA from nuclease degradation and to promote macrophage uptake. Moreover, they led to potent inhibition of TNF-α expression in the lipopolysaccharide-activated mouse macrophage cell line RAW264.7 in vitro model. A significant anti-inflammatory effect in the murine collagen-induced arthritis model was observed through arthritis scoring and histological observations. These results open up essential perspectives in using this original amphiphilic dendron to reduce the disease burden and improve outcomes in chronic inflammatory diseases.

Improving dexamethasone drug loading and efficacy in treating arthritis through a lipophilic prodrug entrapped into PLGA-PEG nanoparticles

Targeted delivery of dexamethasone to inflamed tissues using nanoparticles is much-needed to improve its efficacy while reducing side effects. To drastically improve dexamethasone loading and prevent burst release once injected intravenously, a lipophilic prodrug dexamethasone palmitate (DXP) was encapsulated into poly(DL-lactide-co-glycolide)-polyethylene glycol (PLGA-PEG) nanoparticles (NPs). DXP-loaded PLGA-PEG NPs (DXP-NPs) of about 150 nm with a drug loading as high as 7.5% exhibited low hemolytic profile and cytotoxicity. DXP-NPs were able to inhibit the LPS-induced release of inflammatory cytokines in macrophages. After an intravenous injection to mice, dexamethasone (DXM) pharmacokinetic profile was also significantly improved. The concentration of DXM in the plasma of healthy mice remained high up to 18 h, much longer than the commercial soluble drug dexamethasone phosphate (DSP). Biodistribution studies showed lower DXM concentrations in the liver, kidneys, and lungs when DXP-NPs were administered as compared with the soluble drug. Histology analysis revealed an improvement in the knee structure and reduction of cell infiltration in animals treated with the encapsulated DXP compared with the soluble DSP or non-treated animals. In summary, the encapsulation of a lipidic prodrug of dexamethasone into PLGA-PEG NPs appears as a promising strategy to improve the pharmacological profile and reduce joint inflammation in a murine model of rheumatoid arthritis.

Engineering of small-molecule lipidic prodrugs as novel nanomedicines for enhanced drug delivery

A widely established prodrug strategy can effectively optimize the unappealing properties of therapeutic agents in cancer treatment. Among them, lipidic prodrugs extremely uplift the physicochemical properties, site-specificity, and antitumor activities of therapeutic agents while reducing systemic toxicity. Although great perspectives have been summarized in the progress of prodrug-based nanoplatforms, no attention has been paid to emphasizing the rational design of small-molecule lipidic prodrugs (SLPs). With the aim of outlining the prospect of the SLPs approach, the review will first provide an overview of conjugation strategies that are amenable to SLPs fabrication. Then, the rational design of SLPs in response to the physiological barriers of chemotherapeutic agents is highlighted. Finally, their biomedical applications are also emphasized with special functions, followed by a brief introduction of the promising opportunities and potential challenges of SLPs-based drug delivery systems (DDSs) in clinical application.

Graphical Abstract

Mannosylation Of Budesonide Palmitate Nanoprodrugs For Improved Macrophage Targeting

In a strategy to improve macrophage targeting of glucocorticoids (GCs) for anti-inflammatory therapy, a so-called nanoprodrug of budesonide palmitate decorated by mannose moieties was designed. The synthesis of budesonide palmitate (BP) was obtained by esterification and mannosylated lipid (DSPE-PEG-Man) by reacting 1,2-Distearoyl-sn-Glycero-3-Phosphoethanolamine (DSPE)-polyethylene glycol-amine and α-D-mannopyranosylphenyl isothiocyanate (MPITC). Nanoparticles were formulated by emulsion-evaporation and different ratios of mannosylated lipid were introduced in the formulation of BP nanoprodrugs. Using up to 75% of DSPE-PEG-man (75/25) led to 200 nm particles with a polydispersity index below 0.2, a negative zeta potential ranging from -10 to -30 mV, and one-month stability at 4°C. The encapsulation efficiency of BP approached 100% proving that the prodrug was associated with the particles, leading to a final BP loading of 50-to 60% (w/w). The lectin agglutination test confirmed the availability of mannose on the nanoprodrug surface. Nanoprodrug uptake by RAW 264.7 macrophages was observed by confocal microscopy and flow cytometry. After 24 and 48 hours of incubation, a significantly greater internalization of mannosylated nanoparticles as compared to PEGylated nanoparticles was achieved. The mannose receptor-mediated uptake was confirmed by a mannan inhibition study. After LPS-induced inflammation, the anti-inflammatory effect of mannosylated nanoparticles was assessed. After 48 hours of incubation, cytokines (MCP-1 and TNFα) were reduced demonstrating that the functionalization of nanoprodrugs is possible and efficient.

Synthesized nanoparticles, biomimetic nanoparticles and extracellular vesicles for treatment of autoimmune disease: Comparison and prospect

An emerging strategy is needed to treat autoimmune diseases, many of which are chronic with no definitive cure. Current treatments only alleviate symptoms and have many side effects affecting patient quality of life. Recently, nanoparticle drug delivery systems, an emerging method in medicine, has been used to target cells or organs, without damaging normal tissue. This approach has led to fewer side effects, along with a strong immunosuppressive capacity. Therefore, a nanotechnology approach may help to improve the treatment of autoimmune diseases. In this review, we separated nanoparticles into three categories: synthesized nanoparticles, biomimetic nanoparticles, and extracellular vesicles. This review firstly compares the typical mechanism of action of these three nanoparticle categories respectively in terms of active targeting, camouflage effect, and similarity to parent cells. Then their immunomodulation properties are discussed. Finally, the challenges faced by all these nanoparticles are described.

Tiny dexamethasone palmitate nanoparticles for intravitreal injection: Optimization and in vivo evaluation

Tiny nanoparticles of dexamethasone palmitate (DXP) were designed as transparent suspensions for intravitreal administration to treat age-related macular degeneration (AMD). The influence of three surfactants (PEG-40-stearate and Pluronic block copolymers F68 and F127) on nanoparticles size and stability was investigated and led to an optimal formulation based on Pluronic F127 stabilizing DXP nanoparticles. Size measurements and TEM revealed tiny nanoparticles (around 35 nm) with a low opacity, compatible with further intravitreal injection. X-Ray powder diffraction (XRPD) and transmission electronic microscopy (TEM) performed on freeze-dried samples showed that DXP nanoparticles were rather monodisperse and amorphous. The efficacy of DXP nanoparticles was assessed in vivo on pigmented rabbits with unilateral intravitreal injections. After breakdown of the blood-retinal barrier (BRB) induced by injection of rhVEGF165 with carrier protein, DXP nanoparticles induced a restoration of the BRB 1 month after their intravitreal injection. However, their efficacy was limited in time most probably by clearance of DXP nanoparticles after 2 months due to their small size.

Combining dexamethasone and TNF-α siRNA within the same nanoparticles to enhance anti-inflammatory effect

We propose to combine two therapeutic anti-inflammatory approaches with different mechanisms of action in a single drug delivery system consisting of cationic dexamethasone palmitate nanoparticles (CDXP-NP) associated with TNF-α siRNA. The CDXP-NPs are obtained by the solvent emulsion evaporation technique using dexamethasone palmitate, a prodrug of dexamethasone, associated with a cationic lipid, DOTAP. Their physicochemical properties as well as their ability to bind siRNA were evaluated through gel electrophoresis and siRNA binding quantification. SiRNA cellular uptake was assessed by flow cytometry and confocal microscopy on RAW264.7 macrophages. TNF-α inhibition was determined on LPS-activated RAW264.7 macrophages. Stable and monodisperse nanoparticles around 100 nm with a positive zeta potential (+59 mV) were obtained with an encapsulation efficiency of the prodrug of 95%. A nitrogen/phosphate (N/P) ratio of 10 was selected that conferred the total binding of siRNA to the nanoparticles. Using these CDXP-siRNA-NPs, the siRNA was strongly internalized by RAW264.7 macrophage cells and localized within the cytoplasm. On the LPS-induced RAW264.7 macrophages, a larger inhibition of TNF-α was observed with CDXP-siRNA-NPs compared to CDXP-NPs alone. In conclusion, from these data, it is clear that a combination of DXP and TNF-α siRNA therapy could be a novel strategy and optimized alternative approach to cure inflammatory diseases.

Modular Acid-Activatable Acetone-Based Ketal-Linked Nanomedicine by Dexamethasone Prodrugs for Enhanced Anti-Rheumatoid Arthritis with Low Side Effects

Given the physically encapsulated payloads with drug burst release and/or low drug loading, it is critical to initiate an innovative prodrug strategy to optimize the design of modular nanomedicines. Here, we designed modular pH-sensitive acetone-based ketal-linked prodrugs of dexamethasone (AKP-dexs) and formulated them as nanoparticles. We comprehensively studied the relationships between AKP-dex structure and properties, and we selected two types of AKP-dex-loaded nanoparticles for in vivo studies on the basis of their size, drug loading, and colloidal stability. In a collagen-induced arthritis rat model, these AKP-dex-loaded nanoparticles showed higher accumulation in inflamed joints and better therapeutic efficacy than free dexamethasone phosphate with less-severe side effects. AKP-dex-loaded nanoparticles may be useful for treating other inflammatory diseases and thus have great translational potential. Our findings represent an important step toward the development of practical applications for acetone-based ketal-linked prodrugs and are useful in the design of modular nanomedicines.

Nanomedicines for the delivery of glucocorticoids and nucleic acids as potential alternatives in the treatment of rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease that affects 0.5-1% of the world population. Current treatments include on one hand non-steroidal anti-inflammatory drugs and glucocorticoids (GCs) for treating pain and on the other hand disease-modifying anti-rheumatic drugs such as methotrexate, Janus kinase inhibitors or biologics such as antibodies targeting mainly cytokine expression. More recently, nucleic acids such as siRNA, miRNA, or anti-miRNA have shown strong potentialities for the treatment of RA. This review discusses the way nanomedicines can target GCs and nucleic acids to inflammatory sites, increase drug penetration within inflammatory cells, achieve better subcellular distribution and finally protect drugs against degradation. For GCs such a targeting effect would allow the treatment to be more effective at lower doses and to reduce the administration frequency as well as to induce much fewer side-effects. In the case of nucleic acids, particularly siRNA, knocking down proteins involved in RA, could importantly be facilitated using nanomedicines. Finally, the combination of both siRNA and GCs in the same carrier allowed for the same cell to target both the GCs receptor as well as any other signaling pathway involved in RA. Nanomedicines appear to be very promising for the delivery of conventional and novel drugs in RA therapeutics. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Biology-Inspired Nanomaterials > Nucleic Acid-Based Structures.

Development Of Novel Liposome-Encapsulated Combretastatin A4 Acylated Derivatives: Prodrug Approach For Improving Antitumor Efficacy

Purpose

The objective of the present study was to develop a liposomal drug delivery system based on combretastatin A4 (CA4) prodrugs modified with varying alkyl chains and investigate the in vitro drug conversion from prodrug and in vivo antitumor effect.

Methods

The prodrug of CA4 was synthesized with stearyl chloride (18-carbon chain), palmitoyl chloride (16-carbon chain), myristoyl chloride (14-carbon chain), decanoyl chloride (10-carbon chain), and hexanoyl chloride (6-carbon chain) at the 3′-position of the CA4. Subsequently, it was encapsulated with liposomes through the thin-film evaporation method. Furthermore, the characteristics of prodrug-liposome were evaluated using in vitro drug release, conversion, and cytotoxicity assays, as well as in vivo pharmacokinetic, antitumor, and biodistribution studies.

Results

The liposome system with loaded CA4 derivatives was successfully developed with nano-size and electronegative particles. The rate of in vitro drug release and conversion was reduced as the fatty acid carbon chain lengthened. On the contrary, in vivo antitumor effects were improved with the enlargement of the fatty acid carbon chain. The results of the in vivo pharmacokinetic and tissue distribution studies indicated that the reduced rate of CA4 release with a long carbon chain could prolong the circulation time and increase the drug concentration in the tumor tissue.

Conclusion

These results suggested that the release or hydrolysis of the parent drug from the prodrug was closely related with the in vitro and in vivo properties. The slow drug release of CA4 modified with longer acyl chain could prolong the circulation time and increase the concentration of the drug in the tumor tissue. These effects play a critical role in increasing the antitumor efficacy.