Risperidone-Loaded PLGA-Lipid Particles with Improved Release Kinetics: Manufacturing and Detailed Characterization by Electron Microscopy and Nano-CT

Evaluation of HPV-loaded PLGA microparticles as single-dose HPV vaccine: Insights for sustained-release vaccine development

The human papillomavirus (HPV) vaccine is pivotal to prevent new HPV infections and associated diseases globally, which requires a multi-dose regimen to maximize protection. A long-acting HPV vaccine that can be administered in a single immunization during a doctor's visit would be highly desirable if comparable benefits are provided to that of standard of care (SoC). This work explored the development of a sustained-release HPV vaccine formulation via temperature-programmed loading of polylactic-co-glycolic acid (PLGA) microparticles (MPs). Traditional methods for fabricating HPV-loaded MPs suffer from HPV virus-like particles (VLP) structure/function loss due to exposure to organic solvents, shear stress, etc. This approach separates the microparticle fabrication from VLP loading thereby effectively minimized common stress conditions during formulation. The HPV-loaded PLGA MPs demonstrated significantly prolonged injection site retention as a depot and successfully elicited robust immunogenicity in a dose-dependent manner in vivo. However, a single dose of HPV MPs alone resulted in lower immunogenicity compared to GARDASIL®9 (G9, laboratory prepared material equivalent in composition) prime/boost in a rabbit model, likely due to the lack of an effective adjuvant in the formulation. Alternatively, concomitant administration of HPV MPs and G9 at separate injection sites was shown to induce noninferior antibody titers and durable immune response compared to the current SoC multi-dose regimen. It was hypothesized that the bolus dose of G9 served as potent prime while sustained release of HPV antigens from MPs exerted booster effect. Despite the cost benefits and convenience offered by a single injection of HPV vaccine, the co-formulation of HPV MPs with G9 remains a challenging area. In summary, this work successfully demonstrated the feasibility of developing a sustained-release formulation of HPV vaccine and provided valuable insights into challenges and opportunities of formulation design to improve efficacy, safety, and tolerability as a single-dose HPV vaccine.

The role of porosity in polyester microparticles for drug delivery

Polymer microparticles are a cornerstone in the field of injectable sustained delivery systems: They allow the entrapment of various types of hydrophobic or hydrophilic drugs including biopharmaceuticals. Microparticles can be prepared from the material of choice and tailored to specific target sizes. Importantly, they can retain the drug at the local administration site to achieve a sustained drug release for long-term therapeutic effects. This review focuses on the role of porosity of microparticles as a tremendously important property. Principles to prepare porous carriers via different techniques and additives are discussed, emphasizing that porosity is not a static property but can be dynamic, e.g., for particles from polylactide or poly(lactide-co-glycolide). Considering the contribution of porosity in the overall assessment of drug carrier systems, as well as their manipulation/alteration post-production such as by pore closing, will enlarge the understanding of polymer microparticles as an important class of modern pharmaceutical dosage forms.

Designing stable walnut oil Pickering emulsions: Interfacial behavior and zero-order release of stigmasterol and β sitosterol using walnut protein-high methoxyl pectin-gallic acid complexes

To develop stable walnut oil emulsions, this study explored the interaction of phytosterols with walnut protein (WP), high methoxyl pectin (HMP), and gallic acid (GA) complexes, as well as their release mechanisms. Walnut oil Pickering emulsions were stabilized with WP-HMP-GA complexes at varying ratios, enriched with stigmasterol (STI) and β-sitosterol (β SIT). At a WP:HMP-GA ratio of 1:1 30:1, the complex particle size was 55.15 nm, with a contact angle of 68.1° ± 1.3°, improving stability by approximately 22 %. Scanning electron microscopy and Fourier transform infrared spectroscopy confirmed hydrogen bonding and hydrophobic interactions. The emulsions displayed a particle size of 79.43 nm, Zeta potential of -64.56 mV, strong gel network, and significant oxidative stability. Fluorescence spectroscopy and molecular docking revealed β SIT's initial binding, enabling the controlled β SIT, STI with zero-order release. These findings clarify the molecular interactions and release behavior of STI and β SIT from WP-HMP-GA complexes.

Enhancing drug release from PEG-PLGA implants: The role of Hydrophilic Dexamethasone Phosphate in modulating release kinetics and degradation behavior

Poly(lactic-co-glycolic acid) (PLGA) is a prominent biodegradable polymer used in biomedical applications, including drug delivery systems (DDS) and tissue engineering. PLGA's ability to control drug release is often hindered by nonlinear release profiles and slow initial drug release for hydrophobic drugs. This study investigates the incorporation of dexamethasone phosphate (DEXP) into polyethylene glycol-poly(lactic-co-glycolic acid) (PEG-PLGA) implants to enhance the initial release rate of dexamethasone (DEX). Implants were fabricated via hot-melt extrusion with varying DEX to DEXP ratios. X-ray diffraction (XRD) analysis confirmed that DEX remained crystalline in all formulations, whereas DEXP's crystallinity was detectable only in higher concentrations. Energy-dispersive X-ray spectroscopy (EDX) provided insights into the distribution of DEX and DEXP within the polymer matrix. Drug release studies revealed that PEG-PLGA implants accelerated initial drug release with increasing quantity of DEXP, though it also led to a shorter overall release duration. Despite these improvements, all implants exhibited a biphasic release profile. DEXP also influenced the characteristics of the polymer matrix, evidenced by increased swelling, water absorption, and mass loss. 1H NMR analysis revealed a faster decrease in glycolic acid monomers in DEXP-containing implants. These findings demonstrate that DEXP enhances early drug release of DEX-loaded PEG-PLGA implants prepared by hot-melt extrusion. However, balancing initial and sustained release profiles remains challenging.

Polymer microsphere inks for semi-solid extrusion 3D printing at ambient conditions

Extrusion-based 3D printing methods have great potential for manufacturing of personalized polymer-based drug-releasing systems. However, traditional melt-based extrusion techniques are often unsuitable for processing thermally labile molecules. Consequently, methods that utilize the extrusion of semi-solid inks under mild conditions are frequently employed. The rheological properties of the semi-solid inks have a substantial impact on the 3D printability, making it necessary to evaluate and tailor these properties. Here, we report a novel semi-solid extrusion 3D printing method based on utilization of a Carbopol gel matrix containing various concentrations of polymeric microspheres. We also demonstrate the use of a solvent vapor-based post-processing method for enhancing the mechanical strength of the printed objects. As our approach enables room-temperature processing of polymers typically used in the pharmaceutical industry, it may also facilitate the broader application of 3D printing and microsphere technologies in preparation of personalized medicine.

Advanced Drug Delivery Technologies for Enhancing Bioavailability and Efficacy of Risperidone

Multidisciplinary research has been conducted on novel drug delivery technologies to maximize therapeutic advantages while curtailing undesirable reactions. Drugs under BCS Class II often have a low bioavailability because the dissolution phase limits the absorption efficiency. In this review, risperidone was used as a pharmacological model to examine the impact of solubility enhancement at the primary administration site for such pharmaceuticals. For tackling drug-related pertains like disease diagnostics, therapy, and prophylactic measures at the cellular or molecular levels, implementing nanocarriers in therapeutics has significant potential. The comprehensive pharmaceutical compositions of risperidone nano-microparticles that have been developed to alleviate psychosis are highlighted in the study, which also illustrates potential future developments in such domains.

Focused ion beam-scanning electron microscopy provides novel insights of drug delivery phenomena

Scanning electron microscopy (SEM) has long been a standard tool for morphological analyses, providing sub micrometer resolution of pharmaceutical formulations. However, analysis of internal morphologies of such formulations can often be biased due to the introduction of artifacts that originate from sample preparation. A recent advancement in SEM, is the focused ion beam scanning electron microscopy (FIB-SEM). This technique uses a focused ion beam (FIB) to remove material with nanometer precision, to provide virtually sample-independent access to sub-surface structures. The FIB can be combined with SEM imaging capabilities within the same instrumentation. As a powerful analytical tool, electron microscopy and FIB-milling are performed sequentially to produce high-resolution 3D models of structural peculiarities of diverse drug delivery systems or their behavior in a biological environment, i.e. intracellular or -tissue distribution. This review paper briefly describes the technical background of the method, outlines a wide array of potential uses within the drug delivery field, and focuses on intracellular transport where high-resolution images are an essential tool for mechanistical insights.

Synthesis and characterization of chemical engineered PLGA nanosphere: Triggering mechanism of Catechol-O-methyltransferase inhibition on in vivo neurodegeneration

Chemically engineered PLGA nanospheres are one of the emerging technologies for treating neurodegenerative disorders by inhibiting Catechol-O-methyltransferase (COMT). PLGA-MATPM nanospheres were chemically synthesized using PLGA and MATPM (N-allyl-N-(3-(m-tolyloxy)propyl) methioninate). The tailored PLGA nanospheres induce dose-dependent COMT inhibition in competitive kinetic mode. The interactions between COMT and PLGA nanosphere are explained by spectroscopic and molecular dynamics analysis. PLGA-MATPM NPs suppressed the growth of neuroblastoma cells due to the neurodegenerative toxicity of MPTP induction, demonstrating its potency as a cure for neurological disorders. PLGA-MATPM NPs cross the blood-brain barrier more effectively than those in the blood. Furthermore, PLGA nanospheres showed the most neurodegenerative recovery against MPTP-induced C57BL/6 mice. Using magnetic resonance imaging (MRI), it was validated for quality images of cerebral blood flow (CBF).

Polyester-based long acting injectables: Advancements in molecular dynamics simulation and technological insights

Long-acting injectable (LAI) delivery technologies have enabled the development of several pharmaceutical products that improve patient health by delivering therapeutics from weeks to months. Over the last decade, due to its good biocompatibility, formulation tunability, wide range of degradation rates, and extensive clinical studies, polyester-based LAI technologies including poly(lactic-co-glycolic acid) (PLGA) have made substantial progress. Herein, we discuss PLGA properties with seminal approaches in the development of LAIs, the role of molecular dynamic simulations of polymer-drug interactions, and their effects on quality attributes. We also outline the landscape of various advanced PLGA-based and a few non-PLGA LAI technologies; their design, delivery, and challenges from laboratory scale to preclinical and clinical use; and commercial products incorporating the importance of end-user preferences.

Development of intranasal implantable devices for schizophrenia treatment

In this work the preparation and characterisation of intranasal implants for the delivery of risperidone (RIS) is described. The aim of this work is to develop better therapies to treat chronic conditions affecting the brain such as schizophrenia. This type of systems combines the advantages of intranasal drug delivery with sustained drug release. The resulting implants were prepared using biodegradable materials, including poly(caprolactone) (PCL) and poly(lactic-co-glycolic acid) (PLGA). These polymers were combined with water-soluble compounds, such as poly(ethylene glycol) (PEG) 600, PEG 3000, and Tween® 80 using a solvent-casting method. The resulting implants contained RIS loadings ranging between 25 and 50%. The obtained implants were characterised using a range of techniques including thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), attenuated total reflectance-Fourier transform infrared (ATR-FTIR), X-ray diffraction (XRD), and Scanning Electron Microscopy (SEM). Moreover, in vitro RIS release was evaluated showing that the addition of water-soluble compounds exhibited significant faster release profiles compared to pristine PCL and PLGA-based implants. Interestingly, PCL-based implants containing 25% of RIS and PLGA-based implants loaded with 50% of RIS showed sustained drug release profiles up to 90 days. The former showed faster release rates over the first 28 days but after this period PLGA implants presented higher release rates. The permeability of RIS released from the implants through a model membrane simulating nasal mucosa was subsequently evaluated showing desirable permeation rate of around 2 mg/day. Finally, following in vitro biocompatibility studies, PCL and PLGA-based implants showed acceptable biocompatibility. These results suggested that the resulting implants displayed potential of providing prolonged drug release for brain-targeting drugs.

Journey to the Market: The Evolution of Biodegradable Drug Delivery Systems

Biodegradable polymers have been used as carriers in drug delivery systems for more than four decades. Early work used crude natural materials for particle fabrication, whereas more recent work has utilized synthetic polymers. Applications include the macroscale, the microscale, and the nanoscale. Since pioneering work in the 1960’s, an array of products that use biodegradable polymers to encapsulate the desired drug payload have been approved for human use by international regulatory agencies. The commercial success of these products has led to further research in the field aimed at bringing forward new formulation types for improved delivery of various small molecule and biologic drugs. Here, we review recent advances in the development of these materials and we provide insight on their drug delivery application. We also address payload encapsulation and drug release mechanisms from biodegradable formulations and their application in approved therapeutic products.

Long-lasting rescue of schizophrenia-relevant cognitive impairments via risperidone-loaded microPlates

Schizophrenia is a disorder characterized by cognitive impairment and psychotic symptoms that fluctuate over time and can only be mitigated with the chronic administration of antipsychotics. Here, we propose biodegradable microPlates made of PLGA for the sustained release of risperidone over several weeks. Two microPlate configurations - short: 20 × 20 × 10 μm; tall: 20 × 20 × 20 μm - are engineered and compared to conventional ~ 10 μm PLGA microspheres in terms of risperidone loading and release. Tall microPlates realize the slowest release documenting a 35% risperidone delivery at 100 days with a residual rate of 30 ng/ml. Short microPlates and microspheres present similar release profiles with over 50% of the loaded risperidone delivered within the first 40 days. Then, the therapeutic efficacy of one single intraperitoneal injection of risperidone microPlates is compared to the daily administration of free risperidone in heterozygous knockout mice for dysbindin-1, a clinically relevant mouse model of cognitive and psychiatric liability. In temporal order object recognition tasks, mice treated with risperidone microPlates outperform those receiving free risperidone up to 2, 4, 8, and 12 weeks of observation. This suggests that the sustained release of antipsychotics from one-time microPlate deposition can rescue cognitive impairment in dysbindin mice for up to several weeks. Overall, these results demonstrate that risperidone-loaded microPlates are a promising platform for improving cognitive symptoms associated to schizophrenia. Moreover, the long-term efficacy with one single administration could be of clinical relevance in terms of patient's compliance and adherence to the treatment regimen. Single injection of long-acting risperidone-loaded µPL ameliorates the dysbindin-induced deficit in a clinically relevant mouse model of cognitive and psychiatric liability for up to 12 weeks.

Solvent-Free Fabrication of Biphasic Lipid-Based Microparticles with Tunable Structure

Lipid-based biphasic microparticles are generally produced by long and complex techniques based on double emulsions. In this study, spray congealing was used as a solvent-free fabrication method with improved processability to transform water-in-oil non-aqueous emulsions into spherical solid lipid-based particles with a biphasic structure (b-MPs). Emulsions were prepared by melt emulsification using different compositions of lipids (Dynasan^®118 and Compritol^®888 ATO), surfactants (Cetylstearyl alcohol and Span^®60) and hydrophilic carriers (PEGs, Gelucire^®48/16 and Poloxamer 188). First, pseudo-ternary phase diagrams were constructed to identify the area corresponding to each emulsion type (coarse emulsion or microemulsion). The hydrophobicity of the lipid mostly affected the interfacial tension, and thus the microstructure of the emulsion. Emulsions were then processed by spray congealing and the obtained b-MPs were characterized in terms of thermal and chemical properties (by DSC and FT-IR), external and internal morphology (by SEM, CLSM and Raman mapping). Solid free-flowing spherical particles (main size range 200–355 µm) with different architectures were successfully produced: microemulsions led to the formation of particles with a homogeneous internal structure, while coarse emulsions generated “multicores-shell” particles consisting of variable size hydrophilic cores evenly distributed within the crystalline lipid phase. Depending on their composition and structure, b-MPs could achieve various release profiles, representing a more versatile system than microparticles based on a single lipid phase. The formulation and technological strategy proposed, provides a feasible and cost-effective way of fabricating b-MPs with tunable internal structure and release behavior.

Molecular-Level Release of Coumarin-3-Carboxylic Acid and Warfarin-Derivatives from BSA-Based Hydrogels

This investigation aimed at developing BSA hydrogels as a controlled release system to study the release behavior of spin-labeled coumarin-3-carboxylic acid (SL-CCS) and warfarin (SL-WFR). The release profiles of these spin-labeled (SL-) pharmaceuticals from BSA hydrogels prepared with different procedures are compared in detail. The mechanical properties of the gels during formation and release were studied via rheology, while a nanoscopic view on the release behavior was achieved by analyzing SL-drugs–BSA interaction using continuous wave electron paramagnetic resonance (CW EPR) spectroscopy. The influence of type of drug, drug concentration, duration of gel formation, and gelation methods on release behavior were characterized by CW EPR spectroscopy, EPR imaging (EPRI), and dynamic light scattering (DLS), which provide information on the interaction of BSA with SL-drugs, the percentage of drug inside the hydrogel and the nature and size of the released structures, respectively. We found that the release rate of SL-CCS and SL-WFR from BSA hydrogels is tunable through drug ratios, hydrogel incubation time and gelation procedures. All of the results indicate that BSA hydrogels can be potentially exploited in controlled drug delivery applications.

Long-Acting Risperidone Dual Control System: Preparation, Characterization and Evaluation In Vitro and In Vivo

Schizophrenia, a psychiatric disorder, requires long-term treatment; however, large fluctuations in blood drug concentration increase the risk of adverse reactions. We prepared a long-term risperidone (RIS) implantation system that can stabilize RIS release and established in-vitro and in-vivo evaluation systems. Cumulative release, drug loading, and entrapment efficiency were used as evaluation indicators to evaluate the effects of different pore formers, polymer ratios, porogen concentrations, and oil–water ratios on a RIS implant (RIS-IM). We also built a mathematical model to identify the optimized formulation by stepwise regression. We also assessed the crystalline changes, residual solvents, solubility and stability after sterilization, in-vivo polymer degradation, pharmacokinetics, and tissue inflammation in the case of the optimized formulation. The surface of the optimized RIS microspheres was small and hollow with 134.4 ± 3.5 µm particle size, 1.60 SPAN, 46.7% ± 2.3% implant drug loading, and 93.4% entrapment efficiency. The in-vitro dissolution behavior of RIS-IM had zero-order kinetics and stable blood concentration; no lag time was released for over three months. Furthermore, the RIS-IM was not only non-irritating to tissues but also had good biocompatibility and product stability. Long-acting RIS-IMs with microspheres and film coatings can provide a new avenue for treating schizophrenia.

Muscle Tissue as a Surrogate for In Vitro Drug Release Testing of Parenteral Depot Microspheres

Despite the importance of drug release testing of parenteral depot formulations, the current in vitro methods still require ameliorations in biorelevance. We have investigated here the use of muscle tissue components to better mimic the intramuscular administration. For convenient handling, muscle tissue was used in form of a freeze-dried powder, and a reproducible process of incorporation of tested microspheres to an assembly of muscle tissue of standardized dimensions was successfully developed. Microspheres were prepared from various grades of poly(lactic-co-glycolic acid) (PLGA) or ethyl cellulose, entrapping flurbiprofen, lidocaine, or risperidone. The deposition of microspheres in the muscle tissue or addition of only isolated lipids into the medium accelerated the release rate of all model drugs from microspheres prepared from ester-terminated PLGA grades and ethyl cellulose, however, not from the acid-terminated PLGA grades. The addition of lipids into the release medium increased the solubility of all model drugs; nonetheless, also interactions of the lipids with the polymer matrix (ad- and absorption) might be responsible for the faster drug release. As the in vivo drug release from implants is also often faster than in simple buffers in vitro, these findings suggest that interactions with the tissue lipids may play an important role in these still unexplained observations.

Injectable Lipid-Based Depot Formulations: Where Do We Stand?

The remarkable number of new molecular entities approved per year as parenteral drugs, such as biologics and complex active pharmaceutical ingredients, calls for innovative and tunable drug delivery systems. Besides making these classes of drugs available in the body, injectable depot formulations offer the unique advantage in the parenteral world of reducing the number of required injections, thus increasing effectiveness as well as patient compliance. To date, a plethora of excipients has been proposed to formulate depot systems, and among those, lipids stand out due to their unique biocompatibility properties and safety profile. Looking at the several long-acting drug delivery systems based on lipids designed so far, a legitimate question may arise: How far away are we from an ideal depot formulation? Here, we review sustained release lipid-based platforms developed in the last 5 years, namely oil-based solutions, liposomal systems, in situ forming systems, solid particles, and implants, and we critically discuss the requirements for an ideal depot formulation with respect to the used excipients, biocompatibility, and the challenges presented by the manufacturing process. Finally, we delve into lights and shadows originating from the current setups of in vitro release assays developed with the aim of assessing the translational potential of depot injectables.