Rheological characterization and in vivo evaluation of thermosensitive poloxamer-based hydrogel for intramuscular injection of piroxicam

Parenteral iron nutrition: Iron dextran-poloxamer thermosensitive hydrogel for prolonged intramuscular iron supplementation

The objective of this study was to evaluate the potential of novel poloxamer thermosensitive hydrogels (PTHs) formulations for prolonged release of iron dextran particles (IDP) for intramuscular (IM) injection. The thermosensitive behaviour helps to avoid hepcidin overexpression and toxicity by releasing IDPs without iron accumulation in injection or deposit sites. We hypothesized that novel PTH formulation would prolong iron liberation compared to the commercial iron dextran formulation (FEDEX). PTHs loaded with IDPs were developed with increasing iron content (0.1, 0.2 and 0.4 g of iron/g of poloxamer) and characterized as a prolonged release IM iron supplement. The PTHs had a biocompatible pH for IM injection (6.4) and thermosensitive viscosity, increasing from ∼50 (4 °C) to ∼3000 mPa.s (37 °C). PTHs were successfully injected in the sol state (at 4 °C) into pork meat at 37 °C, transitioning to the gel state in situ (in ∼60-190 s). Structural characterization indicated that there were no PTH-IDP chemical interactions, suggesting that IDP entrapment in PTHs was physical upon gelation. In vitro release studies revealed that iron release from PTH (0.4 g of iron/g of poloxamer) reached 100 % by day 10, whereas 100 % release from FEDEX was complete in 4 h. This novel iron PTH formulation achieved a 60 times long iron release compared to the commercial product. In conclusion, the reported strategy shows adequate IDP entrapment/release properties for prolonged iron release following ex vivo IM injection using biocompatible materials. These results provide a strong basis for future preclinical evaluation to elucidate aspects such as drug release, local irritation, biocompatibility, and efficacy.

Injectable dual thermoreversible hydrogel for sustained intramuscular drug delivery

Herein, we reported novel docetaxel-decorated solid lipid nanoparticle (DCT-SLN)-loaded dual thermoreversible system (DCT-DRTS) for intramuscular administration with reduced burst effect, sustained release and improved antitumor efficacy. The optimized DCT-DRTs was subjected to in-vitro and in-vivo analyses. Antitumor evaluation of the DCT-DRTS was executed and compared with DCT-hydrogel, and DCT-suspension trailed by the histopathological and immune-histochemical analyses. The DCT-SLN gave a mean particle size of 157 nm and entrapment efficiency of 93 %. It was a solid at room temperature, and changed to liquid at physiological temperature due to its melting point of about 32 °C. Unlikely, poloxamer mixture remained liquefied at 25-27 °C, however converted to gel at physiological temperature. This behavior demonstrated opposed reversible property of the DCT-SLN and poloxamer hydrogel in DCT-DRTS system, making it ideal for intramuscular administration and quick gelation inside the body. The DCT-DRTS sustained the drugs release and unlike DCT-hydrogel, the preliminary plasma concentration of DCT-DRTS was significantly reduced, overcoming the burst release. A meaningfully enhanced antitumor efficacy and improved survival rate was observed from DCT-DRTS in tumor cell xenograft athymic nude mice. Additionally, increased apoptotic and reduced proliferation markers were observed in DCT-DRTS treated tumor masses. It was concluded that DCT-DRTS may be a suitable choice for intramuscular administration of DCT with sustained release, improved bioavailability, reduced toxicity and enhanced antitumor effects.

The Advances in Phospholipids-Based Phase Separation Gels for the Sustained Release of Peptides, Proteins, and Chemotherapeutics

Implantable drug delivery systems formed upon injection offer a host of advantages, including localized drug administration, sustained release, minimized side effects, and enhanced patient compliance. Among the various techniques utilized for the development of in situ forming drug implants, solvent-induced phase inversion emerges as a particularly promising approach. However, synthetic polymer-based implants have been associated with undesirable effects arising from polymer degradation. In response to this challenge, a novel category of drug delivery systems, known as phospholipids-based phase separation gels (PPSGs), has emerged. These gels, characterized by their low initial viscosity, exhibit injectability and undergo rapid transformation into in situ implants when exposed to an aqueous environment. A typical PPSG formulation comprises biodegradable components, such as phospholipids, pharmaceutical oil, and a minimal amount of ethanol. The minimized organic solvents in the composition show good biocompatibility. And the relatively simple composition holds promise for industrial-scale manufacturing. This comprehensive review provides an overview of the principles and advancements in PPSG systems, with specific emphasis on their suitability as drug delivery systems for a wide range of active pharmaceutical ingredients (APIs), spanning from small molecules to peptides and proteins. Additionally, we explore the critical parameters and underlying principles governing the formulation of PPSG-based drug delivery strategies, offering valuable insights on optimization strategies.

Bioadhesives with Antimicrobial Properties

Bioadhesives with antimicrobial properties enable easier and safer treatment of wounds as compared to the traditional methods such as suturing and stapling. Composed of natural or synthetic polymers, these bioadhesives seal wounds and facilitate healing while preventing infections through the activity of locally released antimicrobial drugs, nanocomponents, or inherently antimicrobial polers. Although many different materials and strategies are employed to develop antimicrobial bioadhesives, the design of these biomaterials necessitates a prudent approach as achieving all the required properties including optimal adhesive and cohesive properties, biocompatibility, and antimicrobial activity can be challenging. Designing antimicrobial bioadhesives with tunable physical, chemical, and biological properties will shed light on the path for future advancement of bioadhesives with antimicrobial properties. In this review, the requirements and commonly used strategies for developing bioadhesives with antimicrobial properties are discussed. In particular, different methods for their synthesis and their experimental and clinical applications on a variety of organs are reviewed. Advances in the design of bioadhesives with antimicrobial properties will pave the way for a better management of wounds to increase positive clinical outcomes.

Construction and evaluation of a phospholipid-based phase transition in situ gel system for brexpiprazole

The objective of this study was to develop phospholipid-based injectable phase transition in situ gels (PTIGs) for the sustained release of Brexpiprazole (Brex). Phospholipid (Lipoid S100, S100) and stearic acid (SA) were used as the gel matrix which was dissolved in biocompatible solvent medium-chain triglyceride (MCT), N-methyl pyrrolidone (NMP), and ethanol to obtain PTIGs solution. The Brex PTIG showed a solution condition of low viscosity in vitro and was gelatinized in situ in vivo after subcutaneous injection. Both in vitro release assay and in vivo pharmacokinetics study in SD rats displayed that Brex in PTIGs could achieve a sustained release, compared with brexpiprazole solution (Brex-Sol) or brexpiprazole suspension (Brex-Sus). The Brex-PTIGs had good degradability and biocompatibility in vivo with rare inflammation at the injection site. Among the three Brex-PTIG formulations, Brex-PTIG-3 with the SA in the formulation had the greatest gelation viscosity, the lowest initial release rate, and the most stable release profile with sustained release of up to 60 days. The above results indicated that, as a novel drug delivery system, the Brex-PTIGs offered a new option for the clinical treatment of patients with schizophrenia.

Injectable local drug delivery systems for glioblastoma: a systematic review and meta-analysis of progress to date

Glioblastoma (GBM) is an aggressive malignant cancer associated with bleak prognosis and high mortality. The current standard of care for GBM is maximum surgical resection plus radiotherapy and temozolomide (TMZ) chemotherapy. The blood brain barrier (BBB) remains the main obstacle for chemotherapy and severely limits the choice of therapeutic agents. Local treatment allows drugs to circumvent the BBB and reduces systemic side effects. Despite much research effort, to date, no drug delivery system (DDS) designed to be directly injected into brain tumors has been clinically approved, and a systematic overview of the progress in this field, or lack thereof, is missing. In this review, a systematic search of pre-clinical literature was conducted which resulted in 36 original articles on injectable DDS for local treatment of GBM which met the inclusion criteria. A wide range of injectable DDS have been developed and tested pre-clinically which include nanoparticles, liposomes, microspheres, hydrogels and others. meta-Analyses of the included studies showed that, overall, local administration of injectable DDS was beneficial to increase the animal's survival time. Finally, this review summarized the therapeutic effect after local treatment and discussed the shortcomings of the experimental setting in in vivo studies.

Exploration of hemocompatibility and intratumoral accumulation of paclitaxel after loco-regional administration of thermoresponsive hydrogel composed of poloxamer and xanthan gum: An application to dose-dense chemotherapy

Although paclitaxel is a front-line chemotherapeutic agent for the treatment of metastatic breast cancer, its intravenous therapy produces deleterious adverse effects. In an attempt to address the issue, the present study aimed to develop a paclitaxel loaded thermosensitive/thermoresponsive hydrogel (PTXNp-TGel) for loco-regional administration to breast tumors to provide dose-dense chemotherapy. Poloxamer and xanthan gum were used to prepare TGel by the cold method. In vitro and in vivo performance of PTXNp-TGel was compared with TGel, pure drug loaded TGel (PTX-TGel) and marketed formulation, Taxol®. The formulated PTXNp-TGel showed acceptable gelation temperature and time (37 °C and 57 s), lower viscosity at room temperature and higher viscosity at body temperature to support sol-gel transition with increasing temperature, and sustained drug release up to 21 days. Additionally, PTXNp-TGel showed negligible hemolytic toxicity as compared to PTX-TGel and Taxol®. Intratumoral administration of PTXNp-TGel produced significantly higher antitumor activity as indicated by lowest relative tumor volume (1.50) and relative antitumor proliferation rate (27.71 %) in comparison with PTX-TGel, Taxol®, and PTXNp (p < 0.05). Finally, insignificant body weight loss during the experimental period, lack of hematotoxicity, nephrotoxicity, and hepatotoxicity imply improved therapeutic performance of the locally administrated dose-dense therapy of PTXNp-TGel as compared to Taxol®.

Biomedical Applications of Thermosensitive Hydrogels for Controlled/Modulated Piroxicam Delivery

The objectives of this study are the synthesis of thermosensitive poly(N-isopropylacrylamide-co-2-hydroxypropyl methacrylate), p(NiPAm-HPMet), hydrogels and the analysis of a drug-delivery system based on piroxicam, as a model drug, and synthesized hydrogels. A high pressure liquid chromatography method has been used in order to determine both qualitative and quantitative amounts of unreacted monomers and crosslinkers from polymerized hydrogels. Swelling kinetics and the order of a swelling process of the hydrogels have been analyzed at 10 and 40 °C. The copolymers' thermal properties have been monitored by the differential scanning calorimetry (DSC) method. DSC termograms have shown that melting occurs in two temperature intervals (142.36-150.72 °C and 153.14-156.49 °C). A matrix system with incorporated piroxicam has been analyzed by using FTIR and SEM methods. Structural analysis has demonstrated that intermolecular non-covalent interactions have been built between side-groups of copolymer and loaded piroxicam. Morphology of p(NiPAm-HPMet) after drug incorporation indicates the piroxicam presence into the copolymer pores. Kinetic parameters of the piroxicam release from hydrogels at 37 °C and pH 7.4 indicate that the fluid transport mechanism corresponds to Fickian diffusion. As a result, formulation of thermosensitive p(NiPAm-HPMet) hydrogels with incorporated piroxicam could be of interest for further testing as a drug carrier for modulated and prolonged release, especially for topical administration.

An intra-articular injectable phospholipids-based gel for the treatment of rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory and destructive arthropathy with a high deformity rate. Despite numerous studies and clinical trials, no curative treatment is available for large weight-bearing joints. Intra-articular (IA) injections could deliver high concentrations of drug to the afflicted joint and improve the drug efficacy while reducing systemic toxicity. However, free drugs are rapidly cleared from synovial fluid and do not significantly halt the progression of joint disease. Herein, a phospholipids-based controlled-release gel was prepared for sustained IA delivery of celastrol (CEL) and the therapeutic efficiency was evaluated in a rheumatoid arthritis rabbit model. The CEL-loaded gel (CEL-gel) contained up to 70% phospholipids yet was easy to inject. After injecting into the joint cavity, CEL-gel achieved sol to gel phase transition without special stimuli and gelling agent. In vitro release and in vivo pharmacokinetic studies evidenced the stable and sustained release action of CEL-gel. A single IA injection of CEL-gel could maintain therapeutic efficiency for about 25 d and showed much better anti-arthritic efficacy compared to repeated injections of free drug solution (CEL-sol). Furthermore, the IA injection of CEL-gel greatly reduced the systemic toxicity of CEL. With good biocompatibility and biodegradability, CEL-gel might be a promising IA drug delivery system.

Balsam Poplar Buds: Extraction of Potential Phenolic Compounds with Polyethylene Glycol Aqueous Solution, Thermal Sterilization of Extracts and Challenges to Their Application in Topical Ocular Formulations

Phenolic compounds of natural origin have been valued for their beneficial effects on health since ancient times. During our study, we performed the extraction of phenolic compounds from balsam poplar buds using different concentrations of aqueous polyethylene glycol 400 solvents (10-30% PEG400). The aqueous 30% PEG400 extract showed the best phenolic yield. The stability of the extract during autoclave sterilization was evaluated. The extract remained stable under heat sterilization. Ophthalmic formulations are formed using different concentrations (8-15%) of poloxamer 407 (P407) together with hydroxypropyl methylcellulose (0.3%), sodium carboxymethyl cellulose (0.3%) or hyaluronic acid (0.1%). Physicochemical parameters of the formulations remained significantly unchanged after sterilization. Formulations based on 12% P407 exhibited properties characteristic of in situ gels, the gelation point of the formulations was close to the temperature of the cornea. After evaluating the amount of released compounds, it was found that, as the concentration of polymers increases, the amount of released compounds decreases. Formulations based on 15% P407 released the least biologically active compounds. Sterilized formulations remained stable for 30 days.

Imatinib Mesylate-Loaded Rosin/Cinnamon Oil-Based In Situ Forming Gel against Colorectal Cancer Cells

Localized delivery systems have been typically designed to enhance drug concentration at a target site and minimize systemic drug toxicity. A rosin/cinnamon oil (CO) in situ forming gel (ISG) was developed for the sustainable delivery of imatinib mesylate (IM) against colorectal cancer cells. CO has been claimed to express a potent anticancer effect against various cancer cells, as well as a synergistic effect with IM on colorectal cancer cells; however, poor aqueous solubility limits its application. The effect of rosin with the adding CO was assessed on physicochemical properties and in vitro drug release from developed IM-loaded rosin/CO-based ISG. Moreover, in vitro cytotoxicity tests were conducted against two colorectal cancer cells. All formulations exhibited Newtonian flow behavior with viscosity less than 266.9 cP with easier injectability. The adding of CO decreased the hardness and increased the adhesive force of the obtained rosin gel. The gel formation increased over time under microscopic observation. CO-added ISG had a particle-like gel appearance, and it promoted a higher release of IM over a period of 28 days. All tested ISG formulations revealed cytotoxicity against HCT-116 and HT-29 cell lines at different incubation times. Thus, CO-loaded rosin-based ISG can act as a potentially sustainable IM delivery system for chemotherapy against colorectal cancer cells.

Increasing the Hydrophobic Component of Poloxamers and the Inclusion of Salt Extend the Release of Bupivacaine from Injectable In Situ Gels, While Common Polymer Additives Have Little Effect

Various strategies have been applied to reduce the initial burst of drug release and sustain release from poloxamer-based thermoresponsive gels. This work focussed on investigating different formulation approaches to minimise the initial burst of release and sustain the release of the small hydrophilic drug bupivacaine hydrochloride from poloxamer-based thermoresponsive gels. Various in situ gel formulations were prepared by varying the polypropylene oxide (PPO)/polyethylene oxide (PEO) ratio and by adding additives previously described in the literature. It was observed that increasing the PPO/PEO ratio from 0.28 to 0.30 reduced the initial burst release from 17.3% ± 1.8 to 9.1% ± 1.2 during the first six hours and extended the release profile from 10 to 14 days. Notably, the inclusion of sodium chloride (NaCl 0.4% w/w) further reduced the initial burst release to 1.8% ± 1.1 over the first 6 h. Meanwhile, physical blending with additive polymers had a negligible effect on the burst release and overall release profile. The findings suggest that extended release of bupivacaine hydrochloride, with reduced initial burst release, can be achieved simply by increasing the PPO/PEO ratio and the inclusion of NaCl.

Chitosan/guar gum-based thermoreversible hydrogels loaded with pullulan nanoparticles for enhanced nose-to-brain drug delivery

The biopolymers-based two-fold system could provide a sustained release platform for drug delivery to the brain resisting the mucociliary clearance, enzymatic degradation, bypassing the first-pass hepatic metabolism, and BBB thus providing superior bioavailability through intranasal administration. In this study, poloxamers PF-127/PF-68 grafted chitosan HCl-co-guar gum-based thermoresponsive hydrogel loaded with eletriptan hydrobromide laden pullulan nanoparticles was synthesized and subjected to dynamic light scattering, Fourier transform infrared spectroscopy, thermal analysis, x-ray diffraction, scanning electron microscopy, stability studies, mucoadhesive strength and time, gel strength, cloud point assessment, rheological assessment, ex-vivo permeation, cell viability assay, histology studies, and in-vivo Pharmacokinetics studies, etc. It is quite evident that CSG-EH-NPs T-Hgel has an enhanced sustained release drug profile where approximately 86 % and 84 % of drug released in phosphate buffer saline and simulated nasal fluid respectively throughout 48 h compared to EH-NPs where 99.44 % and 97.53 % of the drug was released in PBS and SNF for 8 h. In-vivo PKa parameters i.e., mean residence time (MRT) of 11.9 ± 0.83 compared to EH-NPs MRT of 10.2 ± 0.92 and area under the curve (AUC_tot) of 42,540.5 ± 5314.14 comparing to AUC_tot of EH-NPs 38,026 ± 6343.1 also establish the superiority of CSG-EH-NPs T-Hgel.

Poloxamer-Based Scaffolds for Tissue Engineering Applications: A Review

Poloxamer is a triblock copolymer with amphiphilicity and reversible thermal responsiveness and has wide application prospects in biomedical applications owing to its multifunctional properties. Poloxamer hydrogels play a crucial role in the field of tissue engineering and have been regarded as injectable scaffolds for loading cells or growth factors (GFs) in the last few years. Hydrogel micelles can maintain the integrity and stability of cells and GFs and form an appropriate vascular network at the application site, thus creating an appropriate microenvironment for cell growth, nerve growth, or bone integration. The injectability and low toxicity of poloxamer hydrogels make them a noninvasive method. In addition, they can also be good candidates for bio-inks, the raw material for three-dimensional (3D) printing. However, the potential of poloxamer hydrogels has not been fully explored owing to the complex biological challenges. In this review, the latest progress and cutting-edge research of poloxamer-based scaffolds in different fields of application such as the bone, vascular, cartilage, skin, nervous system, and organs in tissue engineering and 3D printing are reviewed, and the important roles of poloxamers in tissue engineering scaffolds are discussed in depth.

Emerging Fabrication Strategies of Hydrogels and Its Applications

Recently, hydrogels have been investigated for the controlled release of bioactive molecules, such as for living cell encapsulation and matrices. Due to their remote controllability and quick response, hydrogels are widely used for various applications, including drug delivery. The rate and extent to which the drugs reach their targets are highly dependent on the carriers used in drug delivery systems; therefore the demand for biodegradable and intelligent carriers is progressively increasing. The biodegradable nature of hydrogel has created much interest for its use in drug delivery systems. The first part of this review focuses on emerging fabrication strategies of hydrogel, including physical and chemical cross-linking, as well as radiation cross-linking. The second part describes the applications of hydrogels in various fields, including drug delivery systems. In the end, an overview of the application of hydrogels prepared from several natural polymers in drug delivery is presented.

Poloxamer 407 Based Gel Formulations for Transungual Delivery of Hydrophobic Drugs: Selection and Optimization of Potential Additives

The current study aimed to develop poloxamer 407 (P407) gel for transungual delivery of antifungal hydrophobic drugs with sufficient gel strength and drug loading. Gel strength and drug loading of P407 gel was improved by use of functional additives. Hydration enhancement effect was used to select optimum nail penetration enhancer. Face-centered central composite design (FCCCD) was used to observe the effect of the selected penetration enhancer (thioglycolic acid (TGA)) and cosolvent (ethanol) on gelation behavior to develop formulation with enough loading of hydrophobic drug, i.e., terbinafine HCl (TBN), and its permeation across the nail plate without compromising on gel strength. It was observed that increasing concentration of P407 and TGA significantly reduced gelation temperature and enhanced the gel strength of P407 gel and can be used to improve P407 gel strength. Under the scanning electron microscope, the significant effect of TGA as an ungual penetration enhancer was observed on the morphology of the nail plate. Optimized P407 gel prepared with modified cold method showed a gelation temperature of 8.7 ± 0.16 °C, gel strength of 122 ± 7.5 s and drug loading of 1.2% w/w, which was four times more than the drug loading in the gels prepared with conventional cold method. Rheological behavior was pseudoplastic with 47.75 ± 3.48% of gel erosion after 12 washings and 67.21 ± 2.16% of drug release after 12 h. A cumulative amount of TBN permeated from P407 gel with and without PE after 24 h was 27.30 ± 4.18 and 16.69 ± 2.31 µg/cm², respectively. Thioglycolic acid can be used as a nail penetration enhancer without the chemical modification or addition of extra additives while retaining the gel strength. Water miscible cosolvents with moderate evaporability such as ethanol, can be incorporated to P407 gel by minor modification in method of preparation to load the required dose of hydrophobic drugs. Developed P407 gel formulation with sufficient gel strength and drug loading will be a promising carrier for transungual delivery of hydrophobic antifungal agents.

Thermosensitive Hydrogel Harboring CD146/IGF-1 Nanoparticles for Skeletal-Muscle Regeneration

In skeletal-muscle regeneration, it is critical to promote efferocytosis of immune cells and differentiation of satellite cells/postnatal muscle stem cells at the damaged sites. With the optimized poloxamer 407 composition gelled at body temperature, the drugs can be delivered locally. The purpose of this study is to develop a topical injection therapeutic agent for muscle regeneration, sarcopenia, and cachexia. Herein, we construct an injectable, in situ hydrogel system consisting of CD146, IGF-1, collagen I/III, and poloxamer 407, termed CIC gel. The secreted CD146 then binds to VEGFR2 on the muscle surface and effectively induces efferocytosis of neutrophils and macrophages. IGF-1 promotes satellite cell differentiation, and biocompatible collagen evades immune responses of the CIC gel. Consequently, these combined molecules activate muscle regeneration via autophagy and suppress muscle inflammation and apoptosis. Conclusively, we provide an applicable concept of the myogenesis-activating protein formulation, broadening the thermoreversible hydrogel to protein therapeutics for damaged muscle recovery.

An Overview on Thermosensitive Oral Gel Based on Poloxamer 407

In this review, we describe the application of thermosensitive hydrogels composed of poloxamer in medicine, especially for oral cavities. Thermosensitive hydrogels remain fluid at room temperature; at body temperature, they become more viscous gels. In this manner, the gelling system can remain localized for considerable durations and control and prolong drug release. The chemical structure of the poloxamer triblock copolymer leads to an amphiphilic aqueous solution and an active surface. Moreover, the poloxamer can gel by forming micelles in an aqueous solution, depending on its critical micelle concentration and critical micelle temperature. Owing to its controlled-release effect, a thermosensitive gel based on poloxamer 407 (P407) is used to deliver drugs with different characteristics. As demonstrated in studies on poloxamer formulations, an increase in gelling viscosity decreases the drug release rate and gel dissolution time to the extent that it prolongs the drug’s duration of action in disease treatment. This property is used for drug delivery and different therapeutic applications. Its unique route of administration, for many oral diseases, is advantageous over traditional routes of administration, such as direct application and systemic treatment. In conclusion, thermosensitive gels based on poloxamers are suitable and have great potential for oral disease treatment.

Homopolymer and ABC Triblock Copolymer Mixtures for Thermoresponsive Gel Formulations

Our group has recently invented a novel series of thermoresponsive ABC triblock terpolymers based on oligo(ethylene glycol) methyl ether methacrylate with average Mn 300 g mol-1 (OEGMA300, A unit), n-butyl methacrylate (BuMA, B unit) and di(ethylene glycol) methyl ether methacrylate (DEGMA, C unit) with excellent thermogelling properties. In this study, we investigate how the addition of OEGMA300x homopolymers of varying molar mass (MM) affects the gelation characteristics of the best performing ABC triblock terpolymer. Interestingly, the gelation is not disrupted by the addition of the homopolymers, with the gelation temperature (Tgel) remaining stable at around 30 °C, depending on the MM and content in OEGMA300x homopolymer. Moreover, stronger gels are formed when higher MM OEGMA300x homopolymers are added, presumably due to the homopolymer chains acting as bridges between the micelles formed by the triblock terpolymer, thus, favouring gelation. In summary, novel formulations based on mixtures of triblock copolymer and homopolymers are presented, which can provide a cost-effective alternative for use in biomedical applications, compared to the use of the triblock copolymer only.

Injectable Nanocomposite Hydrogels for Cancer Therapy

Hydrogel is a kind of 3D polymer network with strong swelling ability in water and appropriate mechanical and biological properties, which make it feasible to maintain bioactive substances and has promising applications in the fields of biomaterials, soft machines, and artificial tissues. Unfortunately, traditional hydrogels prepared by chemical crosslinking have poor mechanical properties and limited functions, which limit their further application. In recent years, with the continuous development of nanoparticle research, more and more studies have combined nanoparticles with hydrogels to make up for the shortcomings of traditional hydrogels. In this article, the types and functions of hydrogels and nanomaterials are introduced first, as well as the functions and applications of injectable nanocomposite hydrogels (INHs), then the latest progress of INHs for cancer treatment is reviewed, some existing problems are summarized, and the application prospect of NHs is prospected.

Curcumin-laden hyaluronic acid-co-Pullulan-based biomaterials as a potential platform to synergistically enhance the diabetic wound repair

Injectable hydrogel with multifunctional tunable properties comprising biocompatibility, anti-oxidative, anti-bacterial, and/or anti-infection are highly preferred to efficiently promote diabetic wound repair and its development remains a challenge. In this study, we report hyaluronic acid and Pullulan-based injectable hydrogel loaded with curcumin that could potentiate reepithelization, increase angiogenesis, and collagen deposition at wound microenvironment to endorse healing cascade compared to other treatment groups. The physical interaction and self-assembly of hyaluronic acid-Pullulan-grafted-pluronic F127 injectable hydrogel were confirmed using nuclear magnetic resonance (¹H NMR) and Fourier transformed infrared spectroscopy (FT-IR), and cytocompatibility was confirmed by fibroblast viability assay. The CUR-laden hyaluronic acid-Pullulan-g-F127 injectable hydrogel promptly undergoes a sol-gel transition and has proved to potentiate wound healing in a streptozotocin-induced diabetic rat model by promoting 93% of wound closure compared to other groups having 35%, 38%, and 62%. The comparative in vivo study and histological examination was conducted which demonstrated an expeditious recovery rate by significantly reducing the wound healing days i.e. 35 days in a control group, 33 days in the CUR suspension group, 21 days in unloaded injectable, and 13 days was observed in CUR loaded hydrogel group. Furthermore, we suggest that the injectable hydrogel laden with CUR showed a prompt wound healing potential by increasing the cell proliferation and serves as a drug delivery platform for sustained and targeted delivery of hydrophobic moieties.

Recent Advances in Polymer-Based Vaginal Drug Delivery Systems

The vagina has been considered a potential drug administration route for centuries. Most of the currently marketed and investigated vaginal formulations are composed with the use of natural or synthetic polymers having different functions in the product. The vaginal route is usually investigated as an administration site for topically acting active ingredients; however, the anatomical and physiological features of the vagina make it suitable also for drug systemic absorption. In this review, the most important natural and synthetic polymers used in vaginal products are summarized and described, with special attention paid to the properties important in terms of vaginal application. Moreover, the current knowledge on the commonly applied and innovative dosage forms designed for vaginal administration was presented. The aim of this work was to highlight the most recent research directions and indicate challenges related to vaginal drug administrations. As revealed in the literature overview, intravaginal products still gain enormous scientific attention, and novel polymers and formulations are still explored. However, there are research areas that require more extensive studies in order to provide the safety of novel vaginal products.

Electromagnetic field-assisted cell-laden 3D printed poloxamer-407 hydrogel for enhanced osteogenesis

3D bioprinted hydrogel has gained enormous attention, especially in tissue engineering, owing to its attractive structure and excellent biocompatibility. In this study, we demonstrated that 3D bioprinted cell-laden 'thermoresponsive' poloxamer-407 (P407) gels have the potential to stimulate osteogenic differentiation of apical papilla stem cells (SCAPs) under the influence of low voltage-frequency (5 V-1 Hz, 0.62 mT) electromagnetic fields (EMFs). SCAPs were initially used for cell-laden 3D printing to biomimic the apical papilla of human teeth. The developed hydrogel exhibited higher mechanical strength as well as good printability, showing high-quality micro-architecture. Moreover, the as-printed hydrogels (5 mm × 5 mm) were loaded with plasminogen activator inhibitor-1 (PAI-1) for testing the combined effect of PAI-1 and EMFs on SCAP differentiation. Interestingly, the 3D hydrogels showed improved viability and differentiation of SCAPs under EMFs' influence as examined by live/dead assay and alizarin Red-S staining, respectively. Therefore, our results confirmed that P407 hydrogels are non-toxic for encapsulation of SCAPs, yielding high cell viability and accelerate the cell migration potential. The 3D hydrogels with PAI-1 exhibited high mRNA expression levels for osteogenic/odontogenic gene markers (ALP, Col-1, DSPP, and DMP-1) vis-à-vis control after 14 days of in vitro culture. Our findings suggest that 3D bioprinted P407 hydrogels are biocompatible for SCAP encapsulation, and the applied low voltage-frequency EMFs could effectively improve dental tissue regeneration, particularly for oral applications.

Injectable thermoresponsive gels offer sustained dual release of bupivacaine hydrochloride and ketorolac tromethamine for up to two weeks

Bupivacaine and ketorolac are commonly used in combination to reduce perioperative pain. This study aimed to develop and characterize an injectable system that offers simultaneous and prolonged release of bupivacaine and ketorolac. Formulations were prepared using poloxamer 407 with increasing concentrations of poloxamer 188 and sodium chloride. Small Angle X-ray Scattering (SAXS) experiments demonstrated that the poloxamers form gels with a cubic lattice arrangement regardless of the matrix composition, whereas the system porosity is driven by poloxamers concentration. Drug loading slightly reduced the intermicellar spacing. Fourier transform infrared spectroscopy and thermal analysis suggested electrostatic interactions between the loaded drugs and poloxamers. Mechanical and rheological studies confirmed the formulations exhibit Newtonian-like flow at room temperature followed by a transition to a viscous gel at body temperature. Importantly, the developed formulations demonstrated steady and sustained release of both bupivacaine and ketorolac over two weeks. Sodium chloride reduced the initial burst release over the first six hours for BH, from 8.6 ± 0.18% to 1.6 ± 0.11%, and KT, from 7.7 ± 0.27% to 1.5 ± 0.10%. Hence, poloxamer-based thermoresponsive gelling systems are promising delivery platforms for the sustained delivery of bupivacaine and ketorolac, with potential clinical benefits for managing perioperative pain.

Mucoadhesive In Situ Rectal Gel Loaded with Rifampicin: Strategy to Improve Bioavailability and Alleviate Liver Toxicity

Although it is a front-line in tuberculosis treatment, rifampicin (RF) exhibits poor oral bioavailability and hepatotoxicity. Rectal mucoadhesive and in situ rectal gels were developed to overcome drug drawbacks. A RF/polyethylene glycol 6000 co-precipitate was first prepared in different ratios. Based on the drug solubility, the selected ratio was investigated for drug/polymer interaction and then incorporated into in situ rectal gels using Pluronic F127 (15%) and Pluronic F68 (10%) as a gel base and mucoadhesive polymers (HPMC, sodium alginate and chitosan). The formulations were assessed for gelation temperature and gel strength. The selected formulation was investigated for in vivo assessments. The results showed that a 1:1 drug/polymer ratio exhibited satisfying solubility with the recorded drug/polymer interaction. Depending on their concentrations, adding mucoadhesive polymers shifted the gelation temperature to lower temperatures and improved the gel strength. The selected formulation (F4) did not exhibit any anal leakage or marked rectal irritation. Using a validated chromatographic analytical method, F4 exhibited higher drug absorption with a 3.38-fold and 1.74-fold higher bioavailability when compared to oral drug suspension and solid suppositories, respectively. Toxicity studies showed unnoticeable hepatic injury in terms of biochemical, histopathological and immunohistochemical examinations. Together, F4 showed a potential of enhanced performance and also offered lower hepatic toxicity, thus offering an encouraging therapeutic alternative.

Particle and Gel Characterization of Irinotecan-Loaded Double-Reverse Thermosensitive Hydrogel

The irinotecan-loaded double-reverse thermosensitive hydrogel (DRTH) is a dispersed system of irinotecan-loaded solid lipid nanoparticles (SLN) in a thermosensitive hydrogel. To optimise the particle and gel properties of DRTHs for rectal administration of irinotecan, SLNs and DRTHs were prepared with tricaprin, triethanolamine, Tween 80, and Span 20. Among the SLNs tested, an SLN composed of 1 g irinotecan, 0.5 g lipid mixture, and 0.5 g combined surfactant gave the highest entrapment efficiency and smallest particle size. A DRTH composed of (poloxamer 407/poloxamer 188/combined surfactant/SLN dispersion/H₂O (10/15/17/4/54%)) showed easy administration, fast gelling, and strong gel-forming in the body.

Synthesis and characterization of an injectable microparticles integrated hydrogel composite biomaterial: In-vivo biocompatibility and inflammatory arthritis treatment

Polymeric hydrogels and microparticles have been widely used for localized drug delivery applications for the treatment of arthritis. Nonetheless, owing to initial burst drug release, non-specific biodistribution and low retention time at the target site in body, these polymeric drug delivery systems have been found with low in-vivo performance. Hence, the above limitations need to be resolved by designing a smart novel drug delivery system which is the current need in biomedicine. Herein, a novel localized injectable thermoresponsive microparticles embedded hydrogel composite drug delivery system has been developed for the treatment of inflammatory arthritis. In the current study, methotrexate (MTX) loaded alginate microparticles (MTX-Microparticles) are embedded into thermoreversible hydrogel matrix (MTX-MPs-H) prepared by physical blending of sodium hyaluronate and methylcellulose (SHMC). Microparticles-hydrogel composite system exhibited appropriate in-vitro thermoreversibility (sol at 4 °C and gel at 37 °C), biocompatibility (>80 %), hemocompatibility, and controlled drug release profile. The in-vivo biocompatibility studies for 10 days revealed that composite system is non-toxic in nature. The developed MTX-MPs-H composite drug delivery system effectively decreased the swelling/ inflammation of the arthritis affected paw in wistar rats in comparison to only alginate microparticles and pure MTX up to 30 days.

Homo- and co-polymerisation of di(propylene glycol) methyl ether methacrylate – a new monomer

A new methacrylate monomer with two propylene glycol groups on the side chain, di(propylene glycol) methyl ether methacrylate (diPGMA), was synthesised and homo- and co-polymerised for the first time.

Comparison of three in-situ gels composed of different oil types

A phospholipid-based phase separation in-situ gel (PPSG) system, which consists of phospholipids, medium chain oil (triglyceride) and ethanol as basic ingredients, has been previously developed in our lab. In addition, glycerol monooleate (monoglyceride) and glycerol dioleate (diglyceride) were also reported to be able to form liquid crystal gels. Monoglyceride, diglyceride and triglyceride have different degrees of hydroxyl substitution in glycerol and therefore different amphiphilic properties, which may cause different properties of gels composed of them. In this experiment, glycerol monooleate (GMO), glycerol dioleate (GDO) and glycerol trioleate (GTO) were selected to prepare three kinds of PPSGs. We systematically studied their in-vitro and in-vivo physicochemical properties and investigated their drug release behavior with octreotide (OCT) as the model drug. The results showed that PPSG composed of GTO (GTO-gel) had a different microstructure, a slower solvent diffusion speed and the less irritation to skin. In addition, the drug release result showed that the GTO-gel group had a lower initial release rate and a more stable release profile. All results above indicated that GTO-gel had a greater potential as a drug delivery system.

Novel glucosamine-loaded thermosensitive hydrogels based on poloxamers for osteoarthritis therapy by intra-articular injection

Glucosamine (GlcN) is a common drug used to treat osteoarthritis (OA). To prolong the action time of glucosamine on OA and improve its therapeutic effect, this research explored the potential application of GlcN-loaded thermosensitive hydrogels based on poloxamer 407 and poloxamer 188 for OA therapy by intra-articular injection. The thermosensitive hydrogels were prepared by cold method, and the effects of P407, P188, and GlcN on sol-gel transition temperature (T_sol-gel) were compared. After screening was performed, the optimized formulation showed good temperature sensitivity, and T_sol-gel was approximately 35 °C. In vitro release tests showed that GlcN was slowly released from the thermosensitive hydrogels. After the gels were intra-articularly administered to treat OA in rabbits, the degree of swelling and inflammatory factors were significantly decreased in the hydrogel group compared with those in the OA model group (P < 0.05). Histological results showed that the GlcN-administered group had a good repair effect on damaged cartilage. At the same dose, the effect of the thermosensitive hydrogels was better than that of the aqueous solution. Therefore, GlcN-loaded thermosensitive hydrogels based on poloxamers are promising sustainable delivery systems for OA therapy by intra-articular injection.

Thermoresponsive sol-gel improves ocular bioavailability of Dipivefrin hydrochloride and potentially reduces the elevated intraocular pressure in vivo

The present study involves the development of Dipivefrin hydrochloride (DV) containing Poloxamers (P407 and P188)-Carbopol-934 (CP) based thermoresponsive-gels for the management of elevated intraocular pressure (IOP). Optimal formulation was evaluated for gelation temperature (T_gel), physicochemical and viscoelastic properties, in-vitro gel dissolution and drug release studies. The in-vivo safety, precorneal retention, ocular pharmacokinetics and efficacy in reducing IOP were also evaluated. T_gel of DV-containing thermoresponsive-gels were between 35.1 and 38.9 °C and it was Poloxamers and CP concentrations dependent. The optimal formulation (F8), composed of 20% P407, 5% P188 and 0.15% CP (w/v), had a T_gel of 35 °C. Its viscosity indicated good flow at room temperature and ability to convert to gel at ocular temperature and the rheology studies revealed favorable characteristics for its ocular use. In precorneal retention experiment, F8 indicated significantly higher area under concentrations curves as compared to DV-aqueous suspension (DV-AqS). In-vivo ocular pharmacokinetics indicated a significant improvement in ophthalmic bioavailability of epinephrine (active form of DV). F8 was non-irritant to the eyes and showed a successful, continuous and superior ability to reduce IOP compared to DV-AqS in rabbits. In conclusion, our developed system could be an appropriate substitute to the conventional DV eye preparations in the management of elevated IOP.

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.

Investigating the Potential to Deliver and Maintain Plasma and Brain Levels of a Novel Practically Insoluble Methuosis Inducing Anticancer Agent 5-Methoxy MOMIPP Through an Injectable In Situ Forming Thermoresponsive Hydrogel Formulation

A new indole based chalcone molecule MOMIPP induced methuosis mediated cell death in gliobastoma and other cancer cell lines. But the drug was insoluble in water and had a very short plasma half-life. The purpose of this work was to develop a formulation that can provide sustained levels of MOMIPP in vivo. Initial studies established drug solubility in various solvents. N-methyl pyrrolidone (NMP) was determined as an excellent solvent for the drug. Subsequently a poloxamer-407 based thermoreversible gel containing NMP was used to develop the formulation. Rheological studies were performed via oscillatory temperature mode, continuous shear analysis, and oscillatory frequency mode experiments. The mechanical properties of the formulations were tested using a texture profile analyzer. The gelation temperature and time of formulations increased with increasing amounts of NMP. However, the viscosity at 20 °C and storage modulus decreased as the amount of NMP increased. Characterization studies helped to identify the gel formulation that was used to administer the drug orally, sub-cutaneously, and intra-peritoneally. When the gel was given intraperitoneally the target plasma and brain levels of over 5 μM was maintained for about 8 h. Thus, a thermoreversible gel formulation that can deliver MOMIPP in animal studies was successfully developed.

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.

Advances in Therapeutics and Delayed Drug Release

Reducing the frequency of drug administration in the treatment of exotic pets is advantageous because it may decrease handling frequency and thus potential stress and injury risk for the animal, increase owner compliance with the prescribed treatment, and decrease need for general anesthesia in patients that cannot be handled safely. Increasing efficient drug plasma concentration using sustained-released delivery systems is an appealing solution. Potential candidates that could provide a promising solution have been investigated in exotic pets. In this article, the technologies that are the closest to being integrated in exotic pet medicine are reviewed: osmotic pumps, nanoparticles, and hydrogels.

Tunable Two-Compartment On-Demand Sustained Drug Release Based on Lipid Gels

The binary-lipid system of soybean phosphatidylcholine (SPC) and glycerol dioleate (GDO) can hydrate to gels on contacting with aqueous mediums, which has emerged as a versatile and promising delivery matrix for extended drug release applications. In the present work, we have characterized the gelation process of this SPC/GDO lyotropic gel (SGLG) system by rheology and evaluated the drug release profiles from the SGLG formulations with different SPC/GDO mass ratios. Our study has demonstrated that simply adjusting the SPC/GDO mass ratio can tune the lipid gelation behavior and modulate the drug release profiles. More importantly, the drug release from the SGLG formulations follows a two-compartment (fast and slow release compartments) release kinetics that has not been reported before. We posit that the fast release compartment corresponds to the passive diffusion of the drug during the early stage of the gel formation. After the boundary gel phase generation, the drug release is then dominated by the slow diffusion process from SGLG. The pharmacokinetic studies in rats match well with the in vitro studies, suggesting that the binary-lipid formulation is an excellent candidate for on-demand sustained drug delivery system.

Mucosal Applications of Poloxamer 407-Based Hydrogels: An Overview

Poloxamer 407, also known by the trademark Pluronic^® F127, is a water-soluble, non-ionic triblock copolymer that is made up of a hydrophobic residue of polyoxypropylene (POP) between the two hydrophilic units of polyoxyethylene (POE). Poloxamer 407-based hydrogels exhibit an interesting reversible thermal characteristic. That is, they are liquid at room temperature, but they assume a gel form when administered at body temperature, which makes them attractive candidates as pharmaceutical drug carriers. These systems have been widely investigated in the development of mucoadhesive formulations because they do not irritate the mucosal membranes. Based on these mucoadhesive properties, a simple administration into a specific compartment should maintain the required drug concentration in situ for a prolonged period of time, decreasing the necessary dosages and side effects. Their main limitations are their modest mechanical strength and, notwithstanding their bioadhesive properties, their tendency to succumb to rapid elimination in physiological media. Various technological approaches have been investigated in the attempt to modulate these properties. This review focuses on the application of poloxamer 407-based hydrogels for mucosal drug delivery with particular attention being paid to the latest published works.

Chemical Modification of Chitosan for Efficient Vaccine Delivery

Chitosan, which exhibits good biocompatibility, safety, microbial degradation and other excellent performances, has found application in all walks of life. In the field of medicine, usage of chitosan for the delivery of vaccine is favored by a wide range of researchers. However, due to its own natural limitations, its application has been constrained to the beginning of study. In order to improve the applicability for vaccine delivery, researchers have carried out various chemical modifications of chitosan. This review summarizes a variety of modification methods and applications of chitosan and its derivatives in the field of vaccine delivery.

Pharmacokinetics of butorphanol tartrate in a long-acting poloxamer 407 gel formulation administered to Hispaniolan Amazon parrots (Amazona ventralis)

OBJECTIVE To determine pharmacokinetics of butorphanol tartrate incorporated into poloxamer 407 (P407) after SC administration to Hispaniolan Amazon parrots (Amazona ventralis). ANIMALS 11 adult Hispaniolan Amazon parrots (6 males and 5 females; 11 to 27 years old). PROCEDURES A sterile formulation of butorphanol in P407 (But-P407) 25% (percentage determined as [weight of P407/weight of diluent] × 100]) was created (8.3 mg/mL). Five preliminary experiments (2 birds/experiment) were performed to determine the ideal dose for this species. The formulation then was administered (12.5 mg/kg, SC) to 8 birds. Blood samples were collected before (time 0) and 0.08, 0.5, 1, 2, 4, 8, 12, and 24 hours after drug administration. Some birds were used more than once, with a washout period of ≥ 3 months between subsequent treatments. Butorphanol concentrations were quantitated by use of liquid chromatography-tandem mass spectrometry. Pharmacokinetic analysis was performed by use of noncompartmental analysis. RESULTS Maximal plasma butorphanol concentration was reached at 1.31 hours. Plasma concentrations of butorphanol remained > 100 ng/mL for > 3 hours (all birds) or > 4 hours (5/8 birds) but < 8 hours (all birds). Half-life of the terminal slope was 3.41 hours. No adverse effects were detected. CONCLUSIONS AND CLINICAL RELEVANCE Butorphanol was absorbed well from the But-P407 25% by Hispaniolan Amazon parrots, and absorption followed a pharmacokinetic profile compatible with a sustained-release drug. A dose of 12.5 mg/kg, SC, would theoretically provide analgesia for 4 to 8 hours. No adverse effects were detected. Studies on the pharmacodynamics of this formulation are necessary to confirm the degree and duration of analgesia.