Mucosal Applications of Poloxamer 407-Based Hydrogels: An Overview

Cyclosporine Lipid Nanocapsules as Thermoresponsive Gel for Dry Eye Management: Promising Corneal Mucoadhesion, Biodistribution and Preclinical Efficacy in Rabbits

An ophthalmic cyclosporine (CsA) formulation based on Lipid nanocapsules (LNC) was developed for dry eye management, aiming to provide targeting to ocular tissues with long-term drug levels and maximum tolerability. CsA-LNC were of small particle size (41.9 ± 4.0 nm), narrow size distribution (PdI ≤ 0.1), and high entrapment efficiency (above 98%). Chitosan (C) was added to impart positive charge. CsA-LNC were prepared as in-situ gels using poloxamer 407 (P). Ex vivo mucoadhesive strength was evaluated using bovine cornea, while in vivo corneal biodistribution (using fluorescent DiI), efficacy in dry eye using Schirmer tear test (STT), and ocular irritation using Draize test were studied in rabbits compared to marketed ophthalmic CsA nanoemulsion (CsA-NE) and CsA in castor oil. LNC incorporation in in-situ gels resulted in an increase in mucoadhesion, and stronger fluorescence in corneal layers seen by confocal microscopy, compared to the other tested formulations. Rate of recovery (days required to restore corneal baseline hydration level) assessed over 10 days, showed that CsA-LNC formulations produced complete recovery by day 7 comparable to CsA-NE. No Ocular irritation was observed by visual and histopathological examination. Based on data generated, CsA-LNC-CP in-situ gel proved to be a promising effective nonirritant CsA ophthalmic formulation for dry eye management.

Fabrication of oral nanovesicle in-situ gel based on Epigallocatechin gallate phospholipid complex: Application in dental anti-caries

The conventional anti-caries agents exhibit many shortcomings such as poor stability, low efficacy or short residence time in the oral environment, it is urgent to develop efficacy treatments to prevent dental caries. As the most active polyphenols from tea, Epigallocatechin gallate (EGCG) shows remarkable anti-cariogenic bioactivity. However, the poor stability and low bioavailability of EGCG limit its potential application. This study aimed to fabricate nanovesicles in-situ gel based on EGCG phospholipid complex in order to increase its stability and efficacy. The formation of EGCG phospholipid complex was characterized by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The ethanol injection method was used to prepare the EGCG-loaded nanovesicles, an optimal ratio of Poloxamer407 (P407) and Poloxamer188 (P188) as in-situ gel matrix was selected to fabricate oral nanovesicles in-situ gel. EGCG-loaded nanovesicle in-situ gel based on the phospholipid complex had uniform spherical shape without any agglomeration. The discrete nanoparticle with a size (131.44 ± 4.24 nm) and a negative zeta potential value at -30.7 ± 0.5 mV possessed good physical stability and high entrapment efficiency (83.66 ± 3.2%). The formulation exhibited a strong antibacterial activity on S. mutans, which could reduce acid production and tooth surface adhesion. In addition, EGCG formulation could inhibit the formation of glucan and biofilm from S. mutans by suppressing the activity of glycosyltransferase enzymes (GTF). In conclusion, the EGCG-loaded nanovesicle in-situ gel holds great promise as an efficient anti-cariogenic formulation for topical oral delivery.

Biodegradable Polymeric Nanoparticles for Drug Delivery to Solid Tumors

Advances in nanotechnology have favored the development of novel colloidal formulations able to modulate the pharmacological and biopharmaceutical properties of drugs. The peculiar physico-chemical and technological properties of nanomaterial-based therapeutics have allowed for several successful applications in the treatment of cancer. The size, shape, charge and patterning of nanoscale therapeutic molecules are parameters that need to be investigated and modulated in order to promote and optimize cell and tissue interaction. In this review, the use of polymeric nanoparticles as drug delivery systems of anticancer compounds, their physico-chemical properties and their ability to be efficiently localized in specific tumor tissues have been described. The nanoencapsulation of antitumor active compounds in polymeric systems is a promising approach to improve the efficacy of various tumor treatments.

A 61-Year-Old Woman with Chronic Iron-Deficiency Anemia Due to a Cameron Lesion and a Response to Oral Application of Combined Poloxamer 407 with Hyaluronic Acid and Chondroitin Sulfate Following Single Treatment with Pantoprazole: A Case Report

BACKGROUND Cameron lesions are linear erosions and ulcers on the crests of gastric mucosal folds in the neck of a hiatal hernia and can be difficult to diagnose and treat. This report is of a case of chronic iron deficiency in a 61-year-old woman with a late diagnosis of a Cameron lesion, who did not respond to a single treatment with the proton pump inhibitor (PPI) pantoprazole, but was then treated with oral poloxamer 407 with hyaluronic acid and chondroitin sulfate in addition to PPI. CASE REPORT We report the case of a 61-year-old women with recurrent iron-deficiency anemia, first diagnosed 40 years prior to her presentation at our Endoscopy Unit, and an ongoing melena. We discovered an intrahiatal gastric mucosal defect, which we at first treated with proton pump inhibitors and sucralfate. After a follow-up gastroscopy revealed the persistence of the lesion, we decided to incorporate into the treatment a gel-like substance containing, among others, hyaluronic acid and chondroitin sulfate, and observed that the lesion resolved completely. CONCLUSIONS This report highlights that Cameron lesions should be considered in patients with hiatal hernia who have iron-deficiency anemia and can be diagnosed on upper endoscopy. Further clinical studies are required to determine the role of combined poloxamer 407 with hyaluronic acid and chondroitin sulfate in the management of Cameron lesions.

An injectable PEG hydrogel controlling neurotrophin-3 release by affinity peptides

Neurotrophin-3 growth factor can improve cochlear neuron survival, and localized delivery of this protein to the round window membrane in the middle ear may be able to reverse sensorineural hearing loss. Thus, the goal of this work was to develop an injectable hydrogel delivery system that can allow localized release of neurotrophin-3 in a controlled and sustained manner. We identified a PEG hydrogel formulation that uses thiol-vinyl sulfone Michael addition for crosslinking. This injectable formulation provides elastic hydrogels with higher mechanical rigidity, better bio-adhesion and longer residence time than Poloxamer hydrogels currently being investigated clinically for hearing loss. In vivo, PEG hydrogels induce local immune responses comparable to biocompatible Poloxamer hydrogels, yet they released payloads at a ~5-fold slower rate in the subcutaneous area. Based on this injectable hydrogel formulation, we designed an affinity-based protein release system by modifying PEG hydrogels with affinity peptides specific to neurotrophin-3 proteins. We verified the sustained release of neurotrophin-3 from peptide-conjugated PEG hydrogels resulting from the reversible interaction between peptides and proteins. The rate of affinity-controlled release depends on the polymer concentrations, the affinity of peptides and the peptide-to-protein ratios. Collectively, we developed an injectable hydrogel formulation for localized delivery of neurotrophin-3, which provides affinity-controlled release and longer delivery time compared to Poloxamer hydrogels.

Pharmaceutical assessment of polyvinylpyrrolidone (PVP): As excipient from conventional to controlled delivery systems with a spotlight on COVID-19 inhibition

Polyvinylpyrrolidone (PVP) is a water-soluble polymer obtained by polymerization of monomer N-vinylpyrrolidone. PVP is an inert, non-toxic, temperature-resistant, pH-stable, biocompatible, biodegradable polymer that helps to encapsulate and cater both hydrophilic and lipophilic drugs. These advantages enable PVP a versatile excipient in the formulation development of broad conventional to novel controlled delivery systems. PVP has tunable properties and can be used as a brace component for gene delivery, orthopedic implants, and tissue engineering applications. Based on different molecular weights and modified forms, PVP can lead to exceptional beneficial features with varying chemical properties. Graft copolymerization and other techniques assist PVP to conjugate with poorly soluble drugs that can inflate bioavailability and even introduces the desired swelling tract for their control or sustained release. The present review provides chemistry, mechanical, physicochemical properties, evaluation parameters, dewy preparation methods of PVP derivatives intended for designing conventional to controlled systems for drug, gene, and cosmetic delivery. The past and growing interest in PVP establishes it as a promising polymer to enhance the trait and performance of current generation pharmaceutical dosage forms. Furthermore, the scrutiny explores existing patents, marketed products, new and futuristic approaches of PVP that have been identified and scope for future development, characterization, and its use. The exploration spotlights the importance and role of PVP in the design of Povidone-iodine (PVP-I) and clinical trials to assess therapeutic efficacy against the COVID-19 in the current pandemic scenario.

Brain Targeting of Duloxetine HCL via Intranasal Delivery of Loaded Cubosomal Gel: In vitro Characterization, ex vivo Permeation, and in vivo Biodistribution Studies

Purpose

Duloxetine (DLX) is dual serotonin and norepinephrine reuptake inhibitor suffering from limited bioavailability (≈ 40%) due to extensive hepatic metabolism. This work aims to formulate and evaluate DLX intranasal thermoreversible cubosomal gels to enhance its bioavailability and ensure efficient brain targeting.

Materials and Methods

Cubo-gels were prepared by 3³ central composite design with three independent factors, lipid ratio (glycerol monooleate: glycerol tripalmitate), Pluronic F127%, and Pluronic F68%. The prepared formulations were evaluated for their particle size (PS), gelling temperature (GT), entrapment efficiency (EE%), and in vitro release. The cubo-gel with the highest desirability (0.88) was chosen as the optimized formulation. DLX cubo-gel was evaluated using differential scanning calorimetry, Fourier-transform infrared spectroscopy, X-ray powder diffraction, and transmission electron microscopy. Cytotoxicity study, ex vivo permeation study and in vivo bio-distribution study were conducted to evaluate the safety and efficacy of brain targeting.

Results

The optimum cubo-gel was composed of 3.76 lipid ratio, 20% w/v PF127, and 5% w/v PF68. It had PS of 265.13 ± 9.85 nm, GT of 32 ± 0.05°C, EE% of 98.13 ± 0.50%, and showed controlled release behavior where 33% DLX was released within 6 hrs. The plain in situ cubo-gel had a significantly higher IC₅₀ compared to DLX solution and DLX-loaded in situ cubo-gel. The ex vivo permeation study showed 1.27 enhancement in the drug permeation from DLX in situ cubo-gel. According to the in vivo bio-distribution study in plasma and brain, the intranasal DLX in situ cubo-gel showed a 1.96 fold improvement in brain bioavailability compared to the intranasal solution. Its BTE% and DTP% were 137.77 and 10.5, respectively, indicating efficient brain targeting after intranasal administration.

Conclusion

Accordingly, intranasal DLX in situ cubo-gel can be considered as an innovative nano-carrier delivery system for bioavailability enhancement and efficient brain targeting of DLX to maximize its effect.

In situ ophthalmic gel forming systems of poloxamer 407 and hydroxypropyl methyl cellulose mixtures for sustained ocular delivery of chloramphenicole: optimization study by factorial design

Background

Conventional drug delivery systems have some major drawbacks such as low bioavailability, short residence time and rapid precorneal drainage. An in situ gel drug delivery system provides several benefits, such as prolonged pharmacological duration of action, simpler production techniques, and low cost of manufacturing. This research aims to get the optimum formula of chloramphenicol in situ gel based on the physical evaluation.

Methods

The effects of independent variables (poloxamer 407 and hydroxypropyl methyl cellulose (HPMC) concentration) on various dependent variables (gelling capacity, pH and viscosity) were investigated by using 3² factorial design and organoleptic evaluation was done with descriptive analysis.

Results

The optimized formula of chloramphenicol in situ gel yielded 9 variations of poloxamer 407 and HPMC bases composition in % w/v as follows, F1 (5; 0.45), F2 (7.5; 0.45), F3 (10; 0.45), F4 (5; 0.725), F5 (7.5; 0.725), F6 (10; 0.725), F7 (5; 1), F8 (7.5; 1), F9 (10; 1). The results indicated that the organoleptic, pH, and gelling capacity parameters matched all formulas (F1–F9), however, the viscosity parameter only matched F3, F6, F8, and F9. Based on factorial design, F6 had the best formula with desirability value of 0.54, but the design recommended that formula with the composition bases of poloxamer 407 and HPMC at the ratio of 8.16 % w/v and 0.77 % w/v, respectively, was the optimum formula with a desirability value of 0.69.

Conclusion

All formulas have met the Indonesian pharmacopoeia requirements based on the physical evaluation, especially formula 6 (F6), which was supported by the result of factorial design analysis.

Design and Characterization of Glyceryl Monooleate-Nanostructures Containing Doxorubicin Hydrochloride

Glyceryl monooleate (GMO) is one of the most popular amphiphilic lipids, which, in the presence of different amounts of water and a proper amount of stabilizer, can promote the development of well defined, thermodynamically stable nanostructures, called lyotropic liquid crystal dispersions. The aim of this study is based on the design, characterization, and evaluation of the cytotoxicity of lyotropic liquid crystal nanostructures containing a model anticancer drug such as doxorubicin hydrochloride. The drug is efficiently retained by the GMO nanosystems by a remote loading approach. The nanostructures prepared with different non-ionic surfactants (poloxamers and polysorbates) are characterized by different physico-chemical features as a function of several parameters, i.e., serum stability, temperature, and different pH values, as well as the amount of cryoprotectants used to obtain suitable freeze-dried systems. The nanostructures prepared with poloxamer 407 used as a stabilizer show an increased toxicity of the entrapped drug on breast cancer cell lines (MCF-7 and MDA-MB-231) due to their ability to sensitize multidrug-resistant (MDR) tumor cells through the inhibition of specific drug efflux transporters. Moreover, the interaction between the nanostructures and the cells occurs after just a few hours, evidencing a huge cellular uptake of the nanosystems.

Osteogenic effects in a rat osteoporosis model and femur defect model by simvastatin microcrystals

Simvastatin is a translational drug that may be used to induce local bone formation. In this study, simvastatin microcrystals were made by a wet media milling method, and then we verified the osteogenic effect of the microcrystals in rat ovariectomy (OVX)-induced osteoporosis and femur defect models. For the osteoporosis model, we delivered simvastatin microcrystals to the tibia with poloxamer hydrogels via an intraosseous injection. Bone mineral density and the ultimate force of the treated tibia were significantly improved after injection of simvastatin microcrystals at 0.5 and 1 mg compared with the OVX or 0-mg control groups. For the femur defect model, simvastatin microcrystals were incorporated in clinically used calcium phosphate cements (CPCs) as an implant. Quantitative analysis of bone regeneration by microcomputed tomography (μCT) showed improved bone morphology with simvastatin microcrystals at 50 and 100 μg, compared with the CPC vehicle. A semiquantitative scale for histology assessment further demonstrated a higher bone regeneration score in the drug-loaded groups. Our study shows that simvastatin microcrystals can promote bone formation by local delivery using a poloxamer hydrogel or CPC, which may be translationally useful.

Thermosensitive hydrogels for local delivery of 5-fluorouracil as neoadjuvant or adjuvant therapy in colorectal cancer

Spurred by high risk for local tumor recurrence and non-specific toxicity of systemic chemotherapy, clinicians have recently granted a growing interest to locoregional therapeutic strategies. In this perspective, we recently developed a multipurpose thermosensitive hydrogel based on reversible thermogelling properties of poloxamers P407 and P188, a bioadhesive excipient and antineoplastic effect of 5-fluorouracil (5-FU) for the local treatment of colorectal cancer (CRC) in ectopic CT26 murine models. Antitumor efficacy was assessed in mice following intratumoral (IT) injection mimicking neoadjuvant therapy and subcutaneous (SC) application after tumor excision simulating adjuvant therapy. Rheological characterization disclosed that P407/P188/alginate 20/2/1% w/v thermosensitive hydrogel is an injectable free-flowing solution at ambient temperature that undergoes a SOL-GEL transition at 26.0 °C ± 0.6 °C and thereby forms in situ a non-flowing gel at physiological temperature. The generated gel presented an elastic behavior and responded according to a shear-thinning fluid upon shear rate. Although delayed by the addition of alginate 1% w/v, 5-FU is released mainly by diffusion mechanism. The local delivery of 5-FU from P407/P188/alginate/5-FU 20/2/1/0.5% w/v hydrogel in the preclinical tumor models led to a significant tumor growth delay. These results demonstrated that poloxamer-based thermosensitive hydrogels provide a simple and efficient means for local chemotherapeutics delivery.

Clinically adaptable polymer enables simultaneous spatial analysis of colonic tissues and biofilms

Microbial influences on host cells depend upon the identities of the microbes, their spatial localization, and the responses they invoke on specific host cell populations. Multimodal analyses of both microbes and host cells in a spatially resolved fashion would enable studies into these complex interactions in native tissue environments, potentially in clinical specimens. While techniques to preserve each of the microbial and host cell compartments have been used to examine tissues and microbes separately, we endeavored to develop approaches to simultaneously analyze both compartments. Herein, we established an original method for mucus preservation using Poloxamer 407 (also known as Pluronic F-127), a thermoreversible polymer with mucus-adhesive characteristics. We demonstrate that this approach can preserve spatially-defined compartments of the mucus bi-layer in the colon and the bacterial communities within, compared with their marked absence when tissues were processed with traditional formalin-fixed paraffin-embedded (FFPE) pipelines. Additionally, antigens for antibody staining of host cells were preserved and signal intensity for 16S rRNA fluorescence in situ hybridization (FISH) was enhanced in poloxamer-fixed samples. This in turn enabled us to integrate multimodal analysis using a modified multiplex immunofluorescence (MxIF) protocol. Importantly, we have formulated Poloxamer 407 to polymerize and cross-link at room temperature for use in clinical workflows. These results suggest that the fixative formulation of Poloxamer 407 can be integrated into biospecimen collection pipelines for simultaneous analysis of microbes and host cells.

Comparison of Different Chitosan Lipid Nanoparticles for Improved Ophthalmic Tetrandrine Delivery: Formulation, Characterization, Pharmacokinetic and Molecular Dynamics Simulation

In this study, three different chitosan, namely carboxymethyl chitosan (CMC), hydroxypropyl chitosan (HPC) and trimethyl chitosan (TMC) were used as cationic materials to prepare tetrandrine lipid nanoparticles (TET-LNPs) for the treatment of glaucoma. In vitro drug release and pre-corneal retention were used to select the optimal chitosan. In vitro drug release curves of three kinds of LNPs showed a sustained release and TMC-TET-LNPs were the slowest. Moreover, compared with CMC-TET-LNPs and HPC-TET-LNPs, TMC-TET-LNPs had longer corneal retention time. Afterwards, the characteristics of TMC-TET-LNPs were investigated. The ocular irritation study revealed no sign of irritation in rabbit eyes. The pharmacokinetic studies showed that the area under the curve of TMC-TET-LNPs was increased by 2.03 times than TET solution (p < 0.01). Furthermore, the drug biofilm interactions were evaluated by molecular dynamics (MD) simulation. In MD simulation, the strong hydrophobic group of TET interacted with the tail of POPC, making it hard to enter the hydrophobic region of the membrane, thereby restricting TET ocular bioavailability. The experiments and MD simulation indicated that TMC-TET-LNPs had great potential for ocular administration and MD simulation could predict transmembrane transport of drugs.

Engineering of Exosomes: Steps Towards Green Production of Drug Delivery System

Targeting of therapeutic agents to their specific site of action not only increases the treatment efficacy, but also reduces systemic toxicity. Therefore, various drug delivery systems (DDSs) have been developed to achieve this target. However, most of those DDSs have several issues regarding biocompatibility and environmental hazard. In contrast to the synthetic DDSs, exosome-based natural carriers are biocompatible, biodegradable and safe for the environment. Since exosomes play a role in intercellular communication, they have been widely utilized as carriers for different therapeutic agents. This article was aimed to provide an overview of exosomes as an environment-friendly DDS in terms of engineering, isolation, characterization, application and limitation.

GSK3 inhibitor-loaded osteotropic Pluronic hydrogel effectively mitigates periodontal tissue damage associated with experimental periodontitis

Periodontitis is a chronic inflammatory disease caused by complex interactions between the host immune system and pathogens that affect the integrity of periodontium. To prevent disease progression and thus preserve alveolar bone structure, simultaneous anti-inflammatory and osteogenic intervention are essential. Hence, a glycogen synthase kinase 3 beta inhibitor (BIO) was selected as a potent inflammation modulator and osteogenic agent to achieve this treatment objective. BIO's lack of osteotropicity, poor water solubility, and potential long-term systemic side effects, however, have hampered its clinical applications. To address these limitations, pyrophosphorylated Pluronic F127 (F127-PPi) was synthesized and mixed with regular F127 to prepare an injectable and thermoresponsive hydrogel formulation (PF127) of BIO, which could adhere to hard tissue and gradually release BIO to exert its therapeutic effects locally. Comparing to F127 hydrogel, PF127 hydrogels exhibited stronger binding to hydroxyapatite (HA). Additionally, BIO's solubility in PF127 solution was dramatically improved over F127 solution and the improvement was proportional to the polymer concentration. When evaluated on a rat model of periodontitis, PF127-BIO hydrogel treatment was found to be very effective in preserving alveolar bone and ligament, and preventing periodontal inflammation, as shown by the micro-CT and histological data, respectively. Altogether, these findings suggested that the thermoresponsive PF127 hydrogel is an effective local drug delivery system for better clinical management of periodontitis and associated pathologies.

Formulation optimization of smart thermosetting lamotrigine loaded hydrogels using response surface methodology, box benhken design and artificial neural networks

The aim of this research was to develop lamotrigine containing thermosetting hydrogel for intranasal administration to manage and treat generalized epilepsy. Thermosetting hydrogels were prepared using different ratios of poloxamer 407 (L127), poloxamer 188 (L68) and Carbopol^® 974 P NF (C974) using the cold production process. The in situ thermosetting hydrogel was optimized using Box Behken design. Co-solvency approach was used to increase the solubility of lamotrigine by dissolving it in propylene glycol and polyethylene glycol 400 (0.2: 0.8) and the resultant solution was incorporated in the hydrogel to manufacture an LTG hydrogel. The presence of a higher amount of L127 resulted in higher viscosity at 22 °C and 34 °C and decreased the overall release of LTG. An increase in the amount of C974 resulted in a decrease in the pH of the hydrogel. The results show that formulations F10, F12, F13, F14, F15, F16 and F17 exhibited acceptable thermosetting behavior, pH and released adequate Lamotrigine above the minimum effective concentration to treat generalized epilepsy. The optimized formulation exhibited acceptable thermosetting behavior, pH and lamotrigine release but formed a stiff gel at 22 °C. The average LTG content of the optimized hydrogel was 5.00 ± 0.0225 mg/ml with % recovery of 99.17%. The amount of LTG released at 12 h from the optimized hydrogel was 3.21 ± 0.0155 mg and will be therapeutically effective in the brain after absorption via the olfactory region in the nasal cavity.

Characterization and in vitro evaluation of a vaginal gel containing Lactobacillus crispatus for the prevention of gonorrhea

The increasing resistance of Neisseria gonorrhoeae to any current antibiotic treatment and the difficulties associated with the use of prevention means such as condom urge the need for alternative methods to prevent this sexually transmitted infection. In this work, a prevention strategy based on the use of a vaginal gel containing Lactobacilli was assessed in vitro. A Lactobacillus crispatus strain (ATCC 33197) was selected based on the published data on its ability to inhibit Neisseria gonorrhoeae. Its probiotic properties were first characterized. Then, a thermo-sensitive hydrogel containing 21.5% of poloxamer 407, 1% of sodium alginate and 9log₁₀ CFU of Lactobacillus crispatus per gel sample (5 g) was developed. The gelation temperature and the rheological characteristics of this formulation appeared suitable for a vaginal administration. Lactobacillus crispatus was viable in the gel for six months although a large amount of the bacteria was not culturable. The ability of Lactobacillus crispatus to inhibit Neisseria gonorrhoeae was still observed with the gel. Such system, thus, appeared promising for the prevention of gonorrhea.

Nanosized Cubosomal Thermogelling Dispersion Loaded with Saquinavir Mesylate to Improve Its Bioavailability: Preparation, Optimization, in vitro and in vivo Evaluation

Background

Low bioavailability and poor permeability of the blood-brain barrier are problematic when delivering therapeutic agents and particularly anti-human immunodeficiency virus therapy to the central nervous system. The intranasal route offers an alternative for central nervous system delivery. Cubosomes have been reported as helpful vehicles for intranasal delivery of therapeutics to enable brain targeting.

Objective

In this study, we aimed to develop the intranasal cubosomal thermogelling dispersion of saquinavir mesylate for central nervous system delivery.

Methods

The Box-Behnken design was applied to study the effect of monoolein, Poloxamer 407, and polyvinyl alcohol as independent factors and the particle size, entrapment efficiency, gelation temperature, and stability index as responses. The optimized cubosomes were evaluated using transmission electron microscopy, ex vivo permeation, and in vivo pharmacokinetics.

Results

The optimized formula consisting of monoolein (8.96%), Poloxamer 407 (17.45%), and polyvinyl alcohol (7.5%) was prepared and evaluated. Higher values for the steady-state flux, permeability coefficient, and enhancement factor were observed for the cubosomal thermogelling dispersion of saquinavir during ex vivo permeation in comparison with an aqueous suspension of saquinavir. From the pharmacokinetic profile, the relative bioavailability for the intranasal optimized formula was approximately 12-fold higher when compared with oral aqueous suspension and 2.5-fold greater when compared to the intranasal aqueous suspension of saquinavir.

Conclusion

Overall, the saquinavir-loaded cubosomal thermogelling formulation is promising for central nervous system delivery by intranasal administration.

Effect of nintedanib thermo-sensitive hydrogel on neovascularization in alkali burn rat model

AIM

To investigate the effects of nintedanib thermo-sensitive hydrogel (NTH) on neovascularization and related markers in corneal alkali burns of Wistar rats.

METHODS

NTH was prepared by grinding, and its phase-transition temperature was determined. Thirty specific-pathogen-free Wistar rats served as a model of corneal alkali burn in the right eye were randomly divided into 3 groups (n=10, each): model group treated with 0.9% saline once a day, NTH group with 0.2% nintedanib b.i.d, and dexamethasone group with dexamethasone ointment once a day. The left eye of rats served as the controls. The corneal transparency was observed under a slit-lamp microscope, and the area of neovascularization was calculated. On day 7, the rats were sacrificed, and the cornea was removed and embedded with paraffin, then stained with hematoxylin-eosin, and the expression of vascular endothelial growth factor receptor 2 (VEGFR-2) and CD31 in the corneal tissues of each group was detected by immunofluorescence.

RESULTS

The phase-transition temperature of nintedanib obtained by grinding was 37°C after adding artificial tears. The results of the alkali burn model indicated that the growth rate of neovascularization in the NTH group was slower than that in the model group, and the neovascularization area was significantly smaller than that in the model group (P<0.05). Moreover, CD31 and VEGFR-2 expression levels in the NTH group were significantly lower than those in the model group.

CONCLUSION

NTH becomes colloidal at body temperature, which is beneficial for releasing the drug slowly and can significantly inhibit the neovascularization of corneal induced by alkali burn in rats.

Rutin-Loaded Poloxamer 407-Based Hydrogels for In Situ Administration: Stability Profiles and Rheological Properties

Rutin is a flavone glycoside contained in many plants, and exhibits antioxidant, anti-inflammatory, anticancer, and wound-healing properties. The main disadvantage related to the use of this molecule for pharmaceutical application is its poor bioavailability, due to its low solubility in aqueous media. Poloxamer 407-hydrogels show interesting thermo-sensitive properties that make them attractive candidates as pharmaceutical formulations. The hydrophobic domains in the chemical structure of the copolymer, a polymer made up of two or more monomer species, are useful for retaining poorly water-soluble compounds. In this investigation various poloxamer 407-based hydrogels containing rutin were developed and characterized as a function of the drug concentration. In detail, the Turbiscan stability index, the micro- and dynamic rheological profiles and in vitro drug release were investigated and discussed. Rutin (either as a free powder or solubilized in ethanol) did not modify the stability or the rheological properties of these poloxamer 407-based hydrogels. The drug leakage was constant and prolonged for up to 72 h. The formulations described are expected to represent suitable systems for the in situ application of the bioactive as a consequence of their peculiar versatility.

Design and development of a commercially viable in situ nanoemulgel for the treatment of postmenopausal osteoporosis

Aim: To investigate the potential of a thermosensitive intranasal formulation of raloxifene hydrochloride (RH) for systemic delivery with the possibility of enhanced bioavailability and anti-osteoporotic efficacy. Methods: In this work, a commercially scalable nanoemulsion in thermosensitive gel, aligned with better clinical acceptability, has been developed and evaluated. Results: A significant 7.4-fold improvement in bioavailability of RH was recorded when compared with marketed tablets. Likewise, in vivo pharmacodynamics studies suggested 162% enhanced bone density and significantly improved biochemical markers compared with per-oral marketed tablet. Conclusion: The formulation, being safe and patient compliant, successfully tuned anti-osteoporotic effects with improved therapeutic performance. Further, the work provided an exceptional lead to carry out the study in clinical settings.

Thermosensitive in situ liposomal gels loaded with antimicrobial agent for oral care in critically ill patients

Aim: A novel thermosensitive in situ gel loaded with meropenem (MP) liposomes was designed to improve retention in the oral cavity as a prophylactic measure to prevent ventilator-acquired pneumonia in critically ill patients. Methodology & results: Meropenem liposomes were incorporated into poloxamer 407 gels and gamma irradiated. Mean size of liposome was 247 nm, polydispersity index < 0.3 and zeta potential >-25 mV; properties remained unaltered even post sterilization. Permeation study revealed that 75.26% and 34% of MPs were released from MP in situ gel and MP in situ liposomal gel, respectively. The relation between viscosity (cp) and shear rate (1/s) indicate that in situ gels exhibited non-Newtonian behavior at 37°C. The study using Pseudomonas aeruginosa confirmed the antimicrobial activity of meropenem. Conclusion: Prolonged in situ residence, because of rapid gelation process enables an easy administration of meropenem as liposomal suspension in critically ill patients.

Polypseudorotaxanes of Pluronic® F127 with Combinations of α- and β-Cyclodextrins for Topical Formulation of Acyclovir

Acyclovir (ACV) is one of the most used antiviral drugs for the treatment of herpes simplex virus infections and other relevant mucosal infections caused by viruses. Nevertheless, the low water solubility of ACV limits both its bioavailability and antiviral performance. The combination of block copolymer micelles and cyclodextrins (CDs) may result in polypseudorotaxanes with tunable drug solubilizing and gelling properties. However, the simultaneous addition of various CDs has barely been investigated yet. The aim of this work was to design and characterize ternary combinations of Pluronic® F127 (PF127), αCD and βCD in terms of polypseudorotaxane formation, rheological behavior, and ACV solubilization ability and controlled release. The formation of polypseudorotaxanes between PF127 and the CDs was confirmed by FT-IR spectroscopy, X-ray diffraction, and NMR spectroscopy. The effects of αCD/βCD concentration range (0–7% w/w) on copolymer (6.5% w/w) gel features were evaluated at 20 and 37 °C by rheological studies, resulting in changes of the copolymer gelling properties. PF127 with αCD/βCD improved the solubilization of ACV, maintaining the biocompatibility (hen’s egg test on the chorio-allantoic membrane). In addition, the gels were able to sustain acyclovir delivery. The formulation prepared with similar proportions of αCD and βCD provided a slower and more constant release. The results obtained suggest that the combination of Pluronic with αCD/βCD mixtures can be a valuable approach to tune the rheological features and drug release profiles from these supramolecular gels.

Topical Pioglitazone Nanoformulation for the Treatment of Atopic Dermatitis: Design, Characterization and Efficacy in Hairless Mouse Model

Pioglitazone (PGZ) is a drug used to treat type 2 diabetes mellitus that has been reported to show additional therapeutic activities on diverse inflammatory parameters. The aim of this study was to optimize a topical PGZ-loaded nanoemulsion (PGZ-NE) in order to evaluate its effectiveness for treating atopic dermatitis (AD). The composition of the nanoformulation was established by pseudo-ternary diagram. Parameters such as physical properties, stability, in vitro release profile, and ex vivo permeation were determined. The efficacy study was carried out using oxazolone-induced AD model in hairless mice. PGZ-NE released the drug following a hyperbolic kinetic. Additionally, its properties provided high retention potential of drug inside the skin. Therapeutic benefits of PGZ-NE were confirmed on diverse events of the inflammatory process, such as reduction of lesions, enhancement of skin barrier function, diminished infiltration of inflammatory cells, and expression of pro-inflammatory cytokines. These results were reinforced by atomic force microscope (AFM), which demonstrated the ability of the formulation to revert the rigidification caused by oxazolone and consequently improve the elasticity of the skin. These results suggest that PGZ-NE may be a promising treatment for inflammatory dermatological conditions such as AD.

Pharmacotechnical Development of a Nasal Drug Delivery Composite Nanosystem Intended for Alzheimer's Disease Treatment

Direct nose-to-brain delivery has been raised as a non-invasive powerful strategy to deliver drugs to the brain bypassing the blood-brain barrier (BBB). This study aimed at preparing and characterizing an innovative composite formulation, associating the liposome and hydrogel approaches, suitable for intranasal administration. Thermosensitive gel formulations were obtained based on a mixture of two hydrophilic polymers (Poloxamer 407, P407 and Poloxamer 188, P188) for a controlled delivery through nasal route via liposomes of an active pharmaceutical ingredient (API) of potential interest for Alzheimer’s disease. The osmolarity and the gelation temperature (T° sol-gel) of formulations, defined in a ternary diagram, were investigated by rheometry and visual determination. Regarding the issue of assays, a mixture composed of P407/P188 (15/1%, w/w) was selected for intranasal administration in terms of T° sol-gel and for the compatibility with the olfactory mucosal (280 ± 20 mOsmol, pH 6). Liposomes of API were prepared by the thin film hydration method. Mucoadhesion studies were performed by using mucin disc, and they showed the good natural mucoadhesive characteristics of in situ gel formulations, which increased when liposomes were added. The study demonstrated successful pharmacotechnical development of a promising API-loaded liposomes in a thermosensitive hydrogel intended for nasal Alzheimer’s disease treatment.

Formulation strategies to modulate drug release from poloxamer based in situ gelling systems

Introduction: Poloxamer based in situ gelling systems offer numerous advantages in drug delivery; however, their application as prolonged-release delivery platforms is limited mainly due to their weak mechanical properties and the interconnected aqueous network causing fast gel erosion and drug diffusion.Area covered: The focus of this review is to provide an insightful discussion on the formulation strategies that can be employed to sustain/prolong the drug release from poloxamer based in situ gelling systems. The review also outlines the formulation factors, influencing drug release from these systems.Expert opinion: The nature, composition, and concentration of poloxamers are the most critical factors in defining the rate of drug release from an in situ gelling matrix. Hydrophobic gel matrices have compact micellar arrangements resulting in slow diffusion and erosion. Depending on the intended clinical application, gel characteristics can be modulated, either by physical blending or by chemical crosslinking with additive materials, to slow release and improve residence time at the administration site. Incorporating drug-loaded particles into poloxamer gels sustains drug release by creating multiple rate-limiting release barriers. Chemical modification of poloxamers appears to be a promising strategy to obtain prolonged sustained release for parenteral application without compromising the rheological properties of the formulation.

Pluronic-F127/Platelet Microvesicles nanocomplex delivers stem cells in high doses to the bone marrow and confers post-irradiation survival

Platelet microvesicles (pMVs) are submicron-sized heterogeneous vesicles released upon activation and contain several membrane receptors and proteins (CD41, CD61, CD62, CXCR4, PAR-1, etc.). We have revealed their ability to adhere to the triblock copolymer pluronic-F127 (PF127) and form a platelet microvesicular nanocloud which has the potential to enhance the transvascular migration of hematopoietic stem cells across the sinusoidal endothelium to the bone marrow. Besides, the pMVs nanoclouds bestow survival benefits when present on the cells used for infusion, particularly with PF127-stabilized with chitosan-alginate (PF127-CA HSCs). The vesicles were found to be firmly associated with PF127 in the nanocloud, which was detected by confocal laser scanning microscopy. The abrogation of CXCR4/SDF-1 axis regulating the transmigration of the cells by antagonist AMD3100 revealed that the enriched CXCR4 receptors on pMVs robustize the transmigration of the infused cells. The homing of the cells led to effective engraftment and faster regeneration of the critical blood lineages, which elicited 100% survival of the mice receiving lethal doses of radiation. The Human Long-Term Culture Initiating Cells (LTC-ICs), Severe Combined Immunodeficient (SCID) - Repopulating Cells (SRCs) and Colony Forming Cells (CFCs) responsible for the regeneration, but present in extremely low numbers in the infused cell dose, have enabled the cells to reach the bone marrow in high numbers. This potential of the PF127 to sequester the pMVs and its application to achieve over 10-fold delivery of HSCs across the trans-endothelial checkpoint has so far not been reported. Thus, this mechanistic innovation is a potential post-exposure life-saving regimen capable of circumventing the irreparable damage to the bone marrow caused by lethal doses of radiation.

Doxycycline and Monocaprin In Situ Hydrogel: Effect on Stability, Mucoadhesion and Texture Analysis and In Vitro Release

The aim of this study was to develop a stable aqueous formulation containing a combination of doxycycline and monocaprin in clinically relevant concentrations. Increase in expression of Matrix metalloproteinases (MMPs) and microbial role in oral diseases is well established and the combination of above active ingredients could be potentially beneficial in treatment of oral mucosal conditions. The hydrogels containing different concentrations of doxycycline and monocaprin in the presence and absence of stabilizing excipients were developed and their stabilities were studied at 4 °C for up to 1 year. The drug-drug interaction was evaluated using Fourier-transform infrared spectroscopy (FTIR). The addition of monocaprin on doxycycline in situ hydrogel's mucoadhesiveness, texture properties and drug release mechanism was studied. The addition of monocaprin negatively affected the doxycycline stability and was concentration dependent, whereas monocaprin was stable up to 1 year. Doxycycline did not interfere with the anti-Candidal activity of monocaprin. Furthermore, the presence of monocaprin significantly affected the formulation hardness, compressibility and adhesiveness. Monocaprin and doxycycline release followed zero order kinetics and the release mechanism was, by anomalous (non-Fickian) diffusion. The addition of monocaprin increased the drug release time and altered the release mechanism. It is possible to stabilize doxycycline in the presence of monocaprin up to 1 year at 4 °C.

New tools to design smart thermosensitive hydrogels for protein rectal delivery in IBD

Local treatment of Inflammatory Bowel Disease (IBD) has been pointed out to be a novel therapeutic approach with several advantages when compared to conventional therapies. However, the development of systems able to fulfil the requirements of this administration route is not an easy task. The present work suggests the utilization of Artificial Intelligence Tools (AIT) as an instrument to understand polymer-polymer interactions towards obtaining thermosensitive hydrogels suitable for protein rectal administration in IBD. Enemas composed by Pluronic® F127 and F68 and Methocel® K4M were developed and characterised. Two experimental designs were carried out in order to determine the effect of each polymer on their texturometric and rheological behaviour. Using the results of the first experimental design we can justify the inclusion of each raw material PF127, PF68 and MK4M in the formulation and conclude that a compromise solution is necessary to obtain thermosensitive hydrogels of the required properties. The results of the second experimental design allowed concluding that PF127 ruled mainly syringeability and bioadhesion work. On the other hand, PF68 modulated principally gelation temperature, viscosity and protein release from hydrogel matrix. Finally, MK4M influenced bioadhesiveness and mostly determined viscosity. AIT also allowed delimiting the design space to produce easy administrable and highly bioadhesive enemas that undergo fast sol-gel transitions at body temperature.

Spray Congealing: An Emerging Technology to Prepare Solid Dispersions with Enhanced Oral Bioavailability of Poorly Water Soluble Drugs

The low and variable oral bioavailability of poorly water soluble drugs remains a major concern for the pharmaceutical industry. Spray congealing is an emerging technology for the production of solid dispersion to enhance the bioavailability of poorly soluble drugs by using low-melting hydrophilic excipients. The main advantages are the absence of solvents and the possibility to obtain spherical free-flowing microparticles (MPs) by a relatively inexpensive, simple, and one-step process. This review aims to fully describe the composition, structure, physico-chemical properties, and characterization techniques of spray congealed-formulations. Moreover, the influence of these properties on the MPs performance in terms of solubility and dissolution enhancement are examined. Following, an overview of the different spray congealed systems developed to increase the oral drug bioavailability is provided, with a focus on the mechanisms underpinning the bioavailability enhancement. Finally, this work gives specific insights on the main factors to be considered for the rational formulation, manufacturing, and characterization of spray congealed solid dispersions.

An Injectable Click-Crosslinked Hydrogel that Prolongs Dexamethasone Release from Dexamethasone-Loaded Microspheres

Our purpose was to test whether a preparation of injectable formulations of dexamethasone (Dex)-loaded microspheres (Dex-Ms) mixed with click-crosslinked hyaluronic acid (Cx-HA) (or Pluronic (PH) for comparison) prolongs therapeutic levels of released Dex. Dex-Ms were prepared using a monoaxial-nozzle ultrasonic atomizer with an 85% yield of the Dex-Ms preparation, encapsulation efficiency of 80%, and average particle size of 57 μm. Cx-HA was prepared via a click reaction between transcyclooctene (TCO)-modified HA (TCO-HA) and tetrazine (TET)-modified HA (TET-HA). The injectable formulations (Dex-Ms/PH and Dex-Ms/Cx-HA) were fabricated as suspensions and became a Dex-Ms-loaded hydrogel drug depot after injection into the subcutaneous tissue of Sprague Dawley rats. Dex-Ms alone also formed a drug depot after injection. The Cx-HA hydrogel persisted in vivo for 28 days, but the PH hydrogel disappeared within six days, as evidenced by in vivo near-infrared fluorescence imaging. The in vitro and in vivo cumulative release of Dex by Dex-Ms/Cx-HA was much slower in the early days, followed by sustained release for 28 days, compared with Dex-Ms alone and Dex-Ms/PH. The reason was that the Cx-HA hydrogel acted as an external gel matrix for Dex-Ms, resulting in the retarded release of Dex from Dex-Ms. Therefore, we achieved significantly extended duration of a Dex release from an in vivo Dex-Ms-loaded hydrogel drug depot formed by Dex-Ms wrapped in an injectable click-crosslinked HA hydrogel in a minimally invasive manner. In conclusion, the Dex-Ms/Cx-HA drug depot described in this work showed excellent performance on extended in vivo delivery of Dex.

Optimization of composition and obtainment parameters of biocompatible nanoemulsions intended for intraductal administration of piplartine (piperlongumine) and mammary tissue targeting

As a new strategy for treatment of ductal carcinoma in situ, biocompatible and bioadhesive nanoemulsions for intraductal administration of the cytotoxic agent piplartine (piperlongumine) were optimized in this study. To confer bioadhesive properties, the nanoemulsion was modified with chitosan or hyaluronic acid. Tricaprylin was selected as the nanoemulsion non-polar phase due to its ability to dissolve larger drug amounts compared to isopropyl myristate and monocaprylin. Use of phosphatidylcholine as sole surfactant did not result in a homogeneous nanoemulsion, while its association with polysorbate 80 and glycerol (in a surfactant blend) led to the formation of nanoemulsions with droplet size of 76.5 ± 1.2 nm. Heating the aqueous phase to 50 °C enabled sonication time reduction from 20 to 10 min. Inclusion of either chitosan or hyaluronic acid resulted in nanoemulsions with similar in vitro bioadhesive potential, and comparable ability to prolong mammary tissue retention (to 120 h) in vivo without causing undesirable histological alterations. Piplartine was stable in both nanoemulsions for 60 days; however, the size of loaded NE-HA was maintained at a similar range for longer periods of time, suggesting that this nanoemulsion may be a stronger candidate for intraductal delivery.

Thermoreversible Gel-Loaded Amphotericin B for the Treatment of Dermal and Vaginal Candidiasis

The present study was designed to develop a thermoreversible gel of Pluronic (P407) loaded amphotericin B (AmB-gel) for the dermal and vaginal treatment of candidiasis. P407 was used as a copolymer to exploit potential advantages related to increasing drug concentration in the tissue layer in order to provide a local effect. Parameters including internal structure, swelling, porosity, and short-term stability were determined. In addition, drug release profile and ex vivo skin and vaginal permeation studies were carried out. Antifungal efficacy was evaluated against strains of Candida spp. and atomic force microscopy (AFM) supported the results. The tolerance of AmB-gel was studied by evaluating biomechanical properties of skin and determining the irritation level in scarified rabbit skin supported by histological analysis. Results confirmed the development of a thermoreversible AmB-gel with high porosity exhibiting Newtonian behavior at 4 °C and pseudoplasticity at 32 °C as well as optimal stability for at least 90 days. The Amb-gel provided a sustained drug release following a Boltzmann sigmoidal model. Non permeation was observed in skin and vaginal mucosa, showing a high retained amount of AmB of 960.0 and 737.3 µg/g/cm², respectively. In vitro antifungal efficacy showed that AmB-gel was more effective than Free-AmB in inhibiting strains of Candida spp. and these results were corroborated by AFM. Finally, tolerance studies showed that its application did not induce skin irritation nor alter its biophysical properties. Together, these results confirmed that AmB-gel could be proposed as a promising candidate for the clinical status in the treatment of skin and vaginal candidiasis.

Formulation Strategies to Improve Nose-to-Brain Delivery of Donepezil

Donepezil (DPZ) is widely used in the treatment of Alzheimer's disease in tablet form for oral administration. The pharmacological efficacy of this drug can be enhanced by the use of intranasal administration because this route makes bypassing the blood⁻brain barrier (BBB) possible. The aim of this study was to develop a nanoemulsion (NE) as well as a nanoemulsion with a combination of bioadhesion and penetration enhancing properties (PNE) in order to facilitate the transport of DPZ from nose-to-brain. Composition of NE was established using three pseudo-ternary diagrams and PNE was developed by incorporating Pluronic F-127 to the aqueous phase. Parameters such as physical properties, stability, in vitro release profile, and ex vivo permeation were determined for both formulations. The tolerability was evaluated by in vitro and in vivo models. DPZ-NE and DPZ-PNE were transparent, monophasic, homogeneous, and physically stable with droplets of nanometric size and spherical shape. DPZ-NE showed Newtonian behavior whereas a shear thinning (pseudoplastic) behavior was observed for DPZ-PNE. The release profile of both formulations followed a hyperbolic kinetic. The permeation and prediction parameters were significantly higher for DPZ-PNE, suggesting the use of polymers to be an effective strategy to improve the bioadhesion and penetration of the drug through nasal mucosa, which consequently increase its bioavailability.

Drug-Loaded Biocompatible Nanocarriers Embedded in Poloxamer 407 Hydrogels as Therapeutic Formulations

Hydrogels are three-dimensional networks of hydrophilic polymers able to absorb and retain a considerable amount of water or biological fluid while maintaining their structure. Among these, thermo-sensitive hydrogels, characterized by a temperature-dependent sol–gel transition, have been massively used as drug delivery systems for the controlled release of various bioactives. Poloxamer 407 (P407) is an ABA-type triblock copolymer with a center block of hydrophobic polypropylene oxide (PPO) between two hydrophilic polyethyleneoxide (PEO) lateral chains. Due to its unique thermo-reversible gelation properties, P407 has been widely investigated as a temperature-responsive material. The gelation phenomenon of P407 aqueous solutions is reversible and characterized by a sol–gel transition temperature. The nanoencapsulation of drugs within biocompatible delivery systems dispersed in P407 hydrogels is a strategy used to increase the local residence time of various bioactives at the injection site. In this mini-review, the state of the art of the most important mixed systems made up of colloidal carriers localized within a P407 hydrogel will be provided in order to illustrate the possibility of obtaining a controlled release of the entrapped drugs and an increase in their therapeutic efficacy as a function of the biomaterial used.