Application of solid lipid nanoparticles as a long-term drug delivery platform for intramuscular and subcutaneous administration: In vitro and in vivo evaluation

Characterization and Hydrolysis Studies of a Prodrug Obtained as Ester Conjugate of Geraniol and Ferulic Acid by Enzymatic Way

Ferulic acid (Fer) and geraniol (Ger) are natural compounds whose antioxidant and anti-inflammatory activity confer beneficial properties, such as antibacterial, anticancer, and neuroprotective effects. However, the short half-lives of these compounds impair their therapeutic activities after conventional administration. We propose, therefore, a new prodrug (Fer-Ger) obtained by a bio-catalyzed ester conjugation of Fer and Ger to enhance the loading of solid lipid microparticles (SLMs) designed as Fer-Ger delivery and targeting systems. SLMs were obtained by hot emulsion techniques without organic solvents. HPLC-UV analysis evidenced that Fer-Ger is hydrolyzed in human or rat whole blood and rat liver homogenates, with half-lives of 193.64 ± 20.93, 20.15 ± 0.75, and 3.94 ± 0.33 min, respectively, but not in rat brain homogenates. Studies on neuronal-differentiated mouse neuroblastoma N2a cells incubated with the reactive oxygen species (ROS) inductor H2O2 evidenced the Fer-Ger ability to prevent oxidative injury, despite the fact that it appears ROS-promoting. The amounts of Fer-Ger encapsulated in tristearin SLMs, obtained in the absence or presence of glucose, were 1.5 ± 0.1%, allowing the control of the prodrug release (glucose absence) or to sensibly enhance its water dissolution rate (glucose presence). These new "green" carriers can potentially prolong the beneficial effects of Fer and Ger or induce neuroprotection as nasal formulations.

Advanced drug delivery and therapeutic strategies for tuberculosis treatment

Tuberculosis (TB) remains a significant global health challenge, necessitating innovative approaches for effective treatment. Conventional TB therapy encounters several limitations, including extended treatment duration, drug resistance, patient noncompliance, poor bioavailability, and suboptimal targeting. Advanced drug delivery strategies have emerged as a promising approach to address these challenges. They have the potential to enhance therapeutic outcomes and improve TB patient compliance by providing benefits such as multiple drug encapsulation, sustained release, targeted delivery, reduced dosing frequency, and minimal side effects. This review examines the current landscape of drug delivery strategies for effective TB management, specifically highlighting lipid nanoparticles, polymer nanoparticles, inorganic nanoparticles, emulsion-based systems, carbon nanotubes, graphene, and hydrogels as promising approaches. Furthermore, emerging therapeutic strategies like targeted therapy, long-acting therapeutics, extrapulmonary therapy, phototherapy, and immunotherapy are emphasized. The review also discusses the future trajectory and challenges of developing drug delivery systems for TB. In conclusion, nanomedicine has made substantial progress in addressing the challenges posed by conventional TB drugs. Moreover, by harnessing the unique targeting abilities, extended duration of action, and specificity of advanced therapeutics, innovative solutions are offered that have the potential to revolutionize TB therapy, thereby enhancing treatment outcomes and patient compliance.

The interplay between PEGylated nanoparticles and blood immune system

During the last two decades, an increasing number of reports have pointed out that the immunogenicity of polyethylene glycol (PEG) may trigger accelerated blood clearance (ABC) and hypersensitivity reaction (HSR) to PEGylated nanoparticles, which could make PEG modification counterproductive. These phenomena would be detrimental to the efficacy of the load and even life-threatening to patients. Consequently, further elucidation of the interplay between PEGylated nanoparticles and the blood immune system will be beneficial to developing and applying related formulations. Many groups have worked to unveil the relevance of structural factors, dosing schedule, and other factors to the ABC phenomenon and hypersensitivity reaction. Interestingly, the results of some reports seem to be difficult to interpret or contradict with other reports. In this review, we summarize the physiological mechanisms of PEG-specific immune response. Moreover, we speculate on the potential relationship between the induction phase and the effectuation phase to explain the divergent results in published reports. In addition, the role of nanoparticle-associated factors is discussed based on the classification of the action phase. This review may help researchers to develop PEGylated nanoparticles to avoid unfavorable immune responses based on the underlying mechanism.

Recent advances in lipid-based long-acting injectable depot formulations

Long-acting injectable (LAIs) delivery systems sustain the drug therapeutic action in the body, resulting in reduced dosage regimen, toxicity, and improved patient compliance. Lipid-based depots are biocompatible, provide extended drug release, and improve drug stability, making them suitable for systemic and localized treatment of various chronic ailments, including psychosis, diabetes, hormonal disorders, arthritis, ocular diseases, and cancer. These depots include oil solutions, suspensions, oleogels, liquid crystalline systems, liposomes, solid lipid nanoparticles, nanostructured lipid carriers, phospholipid phase separation gel, vesicular phospholipid gel etc. This review summarizes recent advancements in lipid-based LAIs for delivering small and macromolecules, and their potential in managing chronic diseases. It also provides an overview of the lipid depots available in market or clinical phase, as well as patents for lipid-based LAIs. Furthermore, this review critically discusses the current scenario of using in vitro release methods to establish IVIVC and highlights the challenges involved in developing lipid-based LAIs.

Perspectives on cutting-edge nanoparticulate drug delivery technologies based on lipids and their applications

Numerous nanotech arenas in therapeutic biology have recently provided a scientific platform to manufacture a considerable swath of unique chemical entities focusing on drugs. Recently, nanoparticulate drug delivery systems have emerged to deliver a specific drug to a specified site. Among all other carriers, lipids possess features exclusive to nanostructured dosage forms. The bioavailability of orally administered drugs is typically negatively affected by their poor water solubility, resulting from the unique chemical moieties introduced. Because of their unique advantages, lipid nanoparticles must become increasingly predictable as a robust delivery mechanism. The enhanced biopharmaceutical properties and significance of lipid-based targeting technologies such as liposomes, niosomes, solid lipid nanoparticles and micelles are highlighted in this review. Pharmaceutical implications of lipid nanocarriers for the transport and distribution of various therapeutic agents, such as biotechnological products and small pharmaceutical molecules, is a booming topic. Lipid nanoparticles as drug delivery systems have many appealing properties, including high biocompatibility, ease of preparation, tissue specificity, avoidance of reticuloendothelial systems, delayed drug release, scale-up feasibility, nontoxicity and targeted delivery. The use of lipid nanoparticles to enhance the transport of biopharmaceuticals is currently considered state-of-the-art. Similarly, we critically examine the upcoming guidelines that therapeutic scientists should handle.

Role of nanotechnology in the prolonged release of drugs by the subcutaneous route

INTRODUCTION

Subcutaneous physiology is distinct from other parenteral routes that benefit the administration of prolonged-release formulations. A prolonged-release effect is particularly convenient for treating chronic diseases because it is associated with complex and often prolonged posologies. Therefore, drug-delivery systems focused on nanotechnology are proposed as alternatives that can overcome the limitations of current therapeutic regimens and improve therapeutic efficacy.

AREAS COVERED

This review presents an updated systematization of nanosystems, focusing on their applications in highly prevalent chronic diseases. Subcutaneous-delivered nanosystem-based therapies comprehensively summarize nanosystems, drugs, and diseases and their advantages, limitations, and strategies to increase their translation into clinical applications. An outline of the potential contribution of quality-by-design (QbD) and artificial intelligence (AI) to the pharmaceutical development of nanosystems is presented.

EXPERT OPINION

Although recent academic research and development (R&D) advances in the subcutaneous delivery of nanosystems have exhibited promising results, pharmaceutical industries and regulatory agencies need to catch up. The lack of standardized methodologies for analyzing in vitro data from nanosystems for subcutaneous administration and subsequent in vivo correlation limits their access to clinical trials. There is an urgent need for regulatory agencies to develop methods that faithfully mimic subcutaneous administration and specific guidelines for evaluating nanosystems.

Amoxapine-Loaded Solid Lipid Nanoparticles with Superior Preclinical Pharmacokinetics for Better Brain Delivery: LC-MS/MS and GC-MS Analysis

The tricyclic antidepressant amoxapine (AMX) has been reported for a rapid onset of action compared to other cyclic antidepressants. It has very low solubility and bioavailability due to first-pass metabolism. Therefore, we planned to develop solid lipid nanoparticles (SLNs) of AMX using a single emulsification method to increase its solubility and bioavailability. HPLC and LC-MS/MS methods were developed further to quantify AMX in the formulation, plasma, and brain tissue samples. The formulation was studied for entrapment efficiency, loading, and in vitro drug release. Particle size and ζ potential analyses, AFM, SEM, TEM, DSC, and XRD were used for further characterization. In vivo oral pharmacokinetic and brain pharmacokinetic studies were performed using Wistar rats. The entrapment and loading efficiencies of AMX in SLNs were 85.8 ± 3.42 and 4.5 ± 0.45%, respectively. The developed formulation had a mean particle size of 151.5 ± 7.02 nm and a polydispersity index of 0.40 ± 0.11. DSC and XRD results indicated that AMX was incorporated into the nanocarrier system in an amorphous form. SEM, TEM, and AFM studies of AMX-SLNs confirmed the particles' spherical shape and nanoscale size. AMX solubility increased by approx. 2.67 times compared to the pure drug. The developed LC-MS/MS method was successfully applied to the oral and brain pharmacokinetic study of AMX-loaded SLNs in rats. Oral bioavailability was enhanced 1.6 times compared to the pure drug. The peak plasma concentrations of pure AMX and AMX-SLNs were 617.4 ± 137.4 and 1043.5 ± 150.2 (ng/mL), respectively. AMX-SLNs showed more than 5.8 times brain concentration compared to the pure drug. Based on the findings, it appears that utilizing a solid lipid nanoparticle carrier to transport AMX can be a highly effective delivery method with improved pharmacokinetic properties in the brain. This approach may prove valuable for future antidepressant treatment.

Optimization of the different phases of the freeze-drying process of solid lipid nanoparticles using experimental designs

In this work, the effect of cryoprotectant type and concentration and freeze-drying process parameters were evaluated to determine an optimal freeze-drying process for celecoxib-loaded solid lipid nanoparticles. Different cryoprotectants were tested at different weight ratios (cryoprotectant:lipid). Trehalose, maltose, and sucrose at a 1:1 wt ratio were selected for further use in optimizing the freeze-drying process through experimental designs to accurately define the freezing, primary, and secondary drying conditions of the freeze-drying process. The optimal freeze-dried solid lipid nanoparticles were subjected to a 6-month stability study at either 4 °C or 25 °C/60% RH, resulting in significant growth when the nanoparticles were stored at 25 °C/60% RH. The best results were obtained with trehalose as a cryoprotectant and storage at 4 °C. Furthermore, the in vitro release data showed a significantly different release profile before and after optimization of the freeze-drying process, suggesting that the optimization of the freeze-drying process affected the quality of the freeze-dried cake. In conclusion, a successful lyophilization process was obtained due to rational cooperation between a good formulation and optimal conditions in the freezing and drying steps. This yielded an acceptable non-collapsed freeze-dried cake with good redispersibility, minimal changes in physicochemical properties, and long-term stability at 4 °C.

Recent Progress of Solid Lipid Nanoparticles and Nanostructured Lipid Carriers as Ocular Drug Delivery Platforms

Sufficient ocular bioavailability is often considered a challenge by the researchers, due to the complex structure of the eye and its protective physiological mechanisms. In addition, the low viscosity of the eye drops and the resulting short ocular residence time further contribute to the observed low drug concentration at the target site. Therefore, various drug delivery platforms are being developed to enhance ocular bioavailability, provide controlled and sustained drug release, reduce the number of applications, and maximize therapy outcomes. Solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) exhibit all these benefits, in addition to being biocompatible, biodegradable, and susceptible to sterilization and scale-up. Furthermore, their successive surface modification contributes to prolonged ocular residence time (by adding cationic compounds), enhanced penetration, and improved performance. The review highlights the salient characteristics of SLNs and NLCs concerning ocular drug delivery, and updates the research progress in this area.

LC-MS/MS method for the determination of a semi-synthetic phenolic antioxidant 2,6-diisobornyl-4-methylphenol in rats after different administration routes

IBP (2,6-diisobornyl-4-methylphenol) is a small drug molecule with antioxidant properties considered to be a promising neuro-, cardio-, and retinoprotective agent. In this study, a bioanalytical LC-MS/MS method for its determination in rat plasma was developed using 11H-indeno[1,2-b]quinoxalin-11-one oxime as an internal standard (IS). The analytes were extracted from plasma by liquid-liquid extraction technique using isopropyl alcohol:chloroform mixture (1:5, v/v) followed by evaporation and reconstitution of the residues in acetonitrile. The chromatographic separation was carried out on the EC Nucleodur C8 ec column (150 × 4.6 mm, 5 μm) under an isocratic elution mode using acetonitrile and water containing 0.1% (v/v) formic acid (97:3, v/v) as a mobile phase at a flow rate of 0.55 mL/min (40 °C). The IS and IBP were eluted at 3.79 ± 0.02 and 6.30 ± 0.02 min, respectively. The total analysis time was 7.00 min. Multiple reaction monitoring was used to conduct the MS/MS detection in the negative ion mode with transitions at m/z 245.9 → 214.9 (IS) and 379.2 → 256.0 (IBP). Validation studies of the developed method revealed good linearity over the range of 10-5,000 ng/mL. Within- and between-run accuracy was in the range of 92-110%, while within- and between-run precision was below 8%. Additionally, low matrix effects and high recovery (above 98%) were observed. IBP remained stable in rat plasma at room temperature for 4 h, at -80 °C for 21 days, over three freeze-thaw cycles, under vacuum concentrator (45 °C, dried residues) and auto-sampler (15 °C, processed samples) temperatures for 1 h and 24 h, respectively. Subsequently, the validated LC-MS/MS method has been successfully applied to quantitate IBP in actual plasma samples after a single oral, intramuscular, and subcutaneous dose of IBP (10 mg/kg in the peach oil) to rats. Pharmacokinetic studies show that more rapid and complete IBP absorption with a satisfactory excretion rate were observed after oral administration route compared to the intramuscular and subcutaneous ones.

Solid Lipid Nanoparticles Based on Monosubstituted Pillar[5]arenes: Chemoselective Synthesis of Macrocycles and Their Supramolecular Self-Assembly

Novel monosubstituted pillar[5]arenes with one or two terminal carboxyl groups were synthesized by the reaction of succinic anhydride with pillar[5]arene derivative containing a diethylenetriamine function. The ability for non-covalent self-assembly in chloroform, dimethyl sulfoxide, as well as in tetrahydrofuran-water system was studied. The ability of the synthesized macrocycles to form different types of associates depending on the substituent nature was established. The formation of stable particles with average diameter of 192 nm in chloroform and of 439 nm in DMSO was shown for pillar[5]arene containing two carboxyl fragments. Solid lipid nanoparticles (SLN) based on monosubstituted pillar[5]arenes were synthesized by nanoprecipitation in THF-water system. Minor changes in the structure of the macrocycle substituent can dramatically influence the stability and shape of SLN (spherical and rod-like structures) accordingly to DLS and TEM. The presence of two carboxyl groups in the macrocycle substituent leads to the formation of stable spherical SLN with an average hydrodynamic diameter of 364-454 nm. Rod-like structures are formed by pillar[5]arene containing one carboxyl fragment, which diameter is about of 50-80 nm and length of 700-1000 nm. The synthesized stable SLN open up great prospects for their use as drug storage systems.

Approaches for designing and delivering solid lipid nanoparticles of distinct antitubercular drugs

Tuberculosis (TB) is still the biggest infectious disease among adults globally, which effects the social and biological lives of patients as well as the economic liability of healthcare systems. Current treatment regime has challenges with drug resistant (MDR/XDR) strains and the failure of standard therapeutic interventions against these TB strains. In the recent years, several nanocarrier-based drug delivery systems developed (including lipid-based) with anti-tuberculosis drugs via targeted delivery to improve the therapeutic outcomes. In this review, we attempt to summarize on the composition of the reported solid lipid-based particles (SLNPs), their various production methodologies, and properties of the delivery system, and their influence on cellular and pharmacokinetic aspects are also discussed. Besides, we have highlighted anti-TB drugs delivering via lipid-based systems have shown promising outcomes, however clinical translation of such systems is still under investigation. Based on recent advancements and reports, it is recommended that future efforts be made to accelerate the translational development of lipid-based nanocarriers to improve TB treatment.

Effects of Microencapsulated Ferulic Acid or Its Prodrug Methyl Ferulate on Neuroinflammation Induced by Muramyl Dipeptide

Ferulic acid (Fer) is known for its antioxidant and anti-inflammatory activities, which are possibly useful against neurodegenerative diseases. Despite the ability of Fer to permeate the brain, its fast elimination from the body does not allow its therapeutic use to be optimized. The present study proposes the preparation and characterization of tristearin- or stearic acid-based solid lipid microparticles (SLMs) as sustained delivery and targeting systems for Fer. The microparticles were produced by conventional hot emulsion techniques. The synthesis of the methyl ester of Fer (Fer-Me) allowed its encapsulation in the SLMs to increase. Fer-Me was hydrolyzed to Fer in rat whole blood and liver homogenate, evidencing its prodrug behavior. Furthermore, Fer-Me displayed antioxidant and anti-inflammatory properties. The amount of encapsulated Fer-Me was 0.719 ± 0.005% or 1.507 ± 0.014% in tristearin or stearic acid SLMs, respectively. The tristearin SLMs were able to control the prodrug release, while the stearic acid SLMs induced a significant increase of its dissolution rate in water. Jointly, the present results suggest that the tristearin SLMs loaded with Fer-Me could be a potential formulation against peripheral neuropathic pain; conversely, the stearic acid SLMs could be useful for Fer-Me uptake in the brain after nasal administration of the formulation.

The influence on the oral bioavailability of solubilized and suspended drug in a lipid nanoparticle formulation: in vitro and in vivo evaluation

The present study investigated the oral bioavailability of celecoxib when incorporated into solid lipid nanoparticles either dissolved or suspended. In vitro drug release in different media, in vivo performance, and in vitro-in vivo correlation were conducted. The results revealed that the compound was successfully encapsulated into the nanocarriers with good physicochemical properties for oral administration. The in vitro release profiles followed the Weibull model, with significant differences between the formulations containing the solubilized and the suspended compound. Furthermore, in vitro release data could be used to rank the observed in vivo bioavailability. The relative bioavailability of celecoxib from the solid lipid nanoparticles was 2.5- and 1.8-fold higher for the drug solubilized and suspended solid lipid nanoparticle formulation, respectively, when compared to the celecoxib reference. A significant difference was observed between the plasma concentration-time profiles and pharmacokinetic parameters for the three investigated formulations. Finally, this investigation displayed promising outcomes that both solubilized and suspended celecoxib in the lipid core of the solid lipid nanoparticles offers the potential to improve the compound's oral bioavailability and thereby reduce the dosing frequency.

Rat synovial tissue and blood rapamycin pharmacokinetics after intra-articular injection of free solution or nanoparticles vs free rapamycin intravenous shot

Intra-articular (IA) injection of a chondroprotective candidate may delay the osteoarthritis (OA) course, but its rapid absorption into systemic circulation may limit efficacy and produce untoward effects. We compared the pharmacokinetics (PK) of IA rapamycin injected as sustained release in nanoparticles (NPs) versus a free rapamycin suspension in the rat knee compared to an intravenous (IV) free rapamycin shot taken as a reference. Rats received either a single IV injection of free rapamycin (10 µM) or an IA of free or NPs-loaded rapamycin. After sequential exsanguination (15, 30, 60, 180, 360 min, D1, and D7), knee synovial tissue (ST) and cartilage histology were performed. Blood and ST concentrations (LC-MS/MS), PK parameters (area under the curve: AUC; mean residence time: MRT; elimination half-life: T_1/2), and IA biocompatibility were assessed. AUC_IV was significantly higher for IV than for both IA injections (AUC_{IA free} and AUC_{IA NPs}), with 4248 vs 28 and 74 µg.min.L^-1. For ST parameters, we observed a significant difference between AUC_{IA free} and AUC_{IA NPs} with 3735 and 10513 µg.min.L^-1 correspondingly. Articular T_1/2 and MRT were higher after NPs than after free rapamycin injection: 57.8 and 5.0 h for T_1/2 and 80.6 and 5.5 h for MRT, respectively. Histological analysis revealed no chondral injuries and slight transient synovitis only 3 h after the administration of NPs. In the rat knee, rapamycin-loaded NPs delivery via a single IA injection is biocompatible and prolongs synovium joint residency, diminishes blood levels, and reduces detrimental systemic exposure.

RNA-Seq Based Toxicity Analysis of Mesoporous Polydopamine Nanoparticles in Mice Following Different Exposure Routes

Mesoporous polydopamine nanoparticles (MPDA NPs) are promising nanomaterials that have the prospect of clinical application for multi-strategy antitumor therapy, while the biosecurity of MPDA NPs remains indistinct. Here, transcriptome sequencing (RNA-Seq) was performed to systematically reveal the toxicity of MPDA NPs to five categories of organs after three different exposure routes, including intravenous injection, intramuscular injection, and intragastric administration. Our results uncovered that MPDA NPs could be deposited in various organs in small amounts after intravenous administration, not for the other two exposure routes. The number of differentially expressed genes (DEGs) identified in the heart, liver, spleen, lung, and kidney from the intragastric administration group was from 22 to 519. Similarly, the corresponding number was from 23 to 64 for the intramuscular injection group and was from 11 to 153 for the intravenous injection group. Functional enrichment analyses showed 6, 39, and 4 GO terms enriched for DEGs in intragastric administration, intramuscular injection, and intravenous injection groups, respectively. One enriched pathway was revealed in intragastric administration group, while no enriched pathway was found in other groups. Our results indicated that MPDA NPs produced only slight changes at the transcriptome level in mice, which provided new insights for further clinical application of MPDA NPs.

Major difference in particle size, minor difference in release profile: a case study of solid lipid nanoparticles

Solid lipid nanoparticles (SLN) have been widely used in a variety of drug delivery routes, which have the outstanding advantage of controlled drug release. The release of SLN is dominated by many factors, among which the particle size of SLN is a critical one. The aim of this project was to explore the relationship between drug release profile and particle size of SLN. SLN were synthesized via the hot high-pressure homogenization (HPH) method, budesonide (BUD) was used as the model drug, and BUD-SLN1-BUD-SLN4 with increasing particle size was obtained, i.e. 120, 240, 360, and 480 nm. The prepared SLN has good encapsulation efficiency, drug loading capacity, and stability. In vitro release behavior studies showed that the cumulative release of BUD-SLN in Tris-Maleate (Tris-M) media was negligible, while that in Tris-M plus pancreatin media or Tris-M-ethanol media obeyed Ritger-Peppas model or first-order kinetic model, respectively. Noticeably, the release behavior of SLN was to some extent related to the average particle size of SLN, but the correlation was insignificant when the intersection degree of particle size distribution was great. This study provides a new idea for the understanding of in vitro release of SLN and has a certain referencing value for the research and development of novel nanomedicines.