Local anesthetic lidocaine delivery system: chitosan and hyaluronic acid-modified layer-by-layer lipid nanoparticles

Postoperative Multimodal Analgesia Strategy for Enhanced Recovery After Surgery in Elderly Colorectal Cancer Patients

Enhanced Recovery After Surgery (ERAS) protocols have substantially proven their merit in diminishing recuperation durations and mitigating postoperative adverse events in geriatric populations undergoing colorectal cancer procedures. Despite this, the pivotal aspect of postoperative pain control has not garnered the commensurate attention it deserves. Typically, employing a multimodal analgesia regimen that weaves together nonsteroidal anti-inflammatory drugs, opioids, local anesthetics, and nerve blocks stands paramount in curtailing surgical complications and facilitating reduced convalescence within hospital confines. Nevertheless, this integrative pain strategy is not devoid of pitfalls; the specter of organ dysfunction looms over the geriatric cohort, rooted in the abuse of analgesics or the complex interplay of polypharmacy. Revolutionary research is delving into alternative delivery and release modalities, seeking to allay the inadvertent consequences of analgesia and thereby potentially elevating postoperative outcomes for the elderly post-colorectal cancer surgery populace. This review examines the dual aspects of multimodal analgesia regimens by comparing their established benefits with potential limitations and offers insight into the evolving strategies of drug administration and release.

Sustained release local anesthetics for pain management: relevance and formulation approaches

This review attempted to ascertain the rationale for the formulation of sustained-release local anesthetics and summarize the various formulation approaches designed to date to achieve sustained and localized local analgesic effects. The incidence of pain, which is the concern of patients as well as health care professionals, is increasing due to accidents, surgical procedures, and other diseases. Local anesthetics can be used for the management of moderate to severe acute and chronic pain. They also allow regional analgesia, in situations where the cause and source of the pain are limited to a particular site or region, without the need for loss of consciousness or systemic administration of other analgesics thereby decreasing the risk of potential toxicities. Though they have an interesting antipain efficacy, the short duration of action of local anesthetics makes the need for their multiple injections or opioid adjuvants mandatory. To overcome this problem, different formulations are being designed that help achieve prolonged analgesia with a single dose of administration. Combination with adjuvants, liposomal formulations, lipid-based nanoparticles, thermo-responsive nanogels, microspheres, microcapsules, complexation with multivalent counterions and HP-β-CD, lipid-based nanoparticles, and bio-adhesive films, and polymeric matrices are among the approaches. Further safety studies are required to ensure the safe and effective utilization of sustained-release local anesthetics. Moreover, the release kinetics of the various formulations should be adequately established.

Lidocaine-Liposomes-A Promising Frontier for Transdermal Pain Management

(1) Background: We aim to develop novel gel formulations for transdermal drug delivery systems in acute and inflammatory pain therapy. (2) Methods: We induced inflammation by the injection of λ-carrageenan on the hind paw of 80 Wistar male rats. The animals were randomized into eight groups of 10 rats each: C (placebo gel), E (EMLATM), L (lidocaine 2%), L-CD (lidocaine + cyclodextrin 2.5%), L-LP (lidocaine + liposomes 1.7%), L-CS (lidocaine + chitosan 4%), L-CSh (lidocaine + chitosan hydrochloride), and L-CS-LP (lidocaine + chitosan + liposomes). The behavior response was determined with a hot plate, cold plate, and algesimeter, each being performed at 30, 60, 120, 180, and 240 min after pain induction. At the end of the experiment, tissue samples were collected for histological assessment. (3) Results: L-LP had the greatest anesthetic effects, which was proven on the cold plate test compared to placebo and EMLATM (all p ≤ 0.001). L-CS-LP had a significant effect on cold plate evaluation compared to placebo (p ≤ 0.001) and on hot plate evaluation compared to EMLATM (p = 0.018). (4) Conclusions: L-LP is a new substance with a substantial analgesic effect demonstrated by the cold plate in the first 120 min. Further studies with more animals are needed to determine the maximum doses that can be applied for a better analgesia with minimum side effects.

Emerging Anesthetic Nanomedicines: Current State and Challenges

Anesthetics, which include both local and general varieties, are a unique class of drugs widely utilized in clinical surgery to alleviate pain and promote relaxation in patients. Although numerous anesthetics and their traditional formulations are available in the market, only a select few exhibit excellent anesthetic properties that meet clinical requirements. The main challenges are the potential toxic and adverse effects of anesthetics, as well as the presence of the blood-brain barrier (BBB), which makes it difficult for most general anesthetics to effectively penetrate to the brain. Loading anesthetics onto nanocarriers as anesthetic nanomedicines might address these challenges and improve anesthesia effectiveness, reduce toxic and adverse effects, while significantly enhance the efficiency of general anesthetics passing through the BBB. Consequently, anesthetic nanomedicines play a crucial role in the field of anesthesia. Despite their significance, research on anesthetic nanomedicines is still in its infancy, especially when compared to other types of nanomedicines in terms of depth and breadth. Although local anesthetic nanomedicines have received considerable attention and essentially meet clinical needs, there are few reported instances of nanomedicines for general anesthetics. Given the extensive usage of anesthetics and the many of them need for improved performance, emerging anesthetic nanomedicines face both unparalleled opportunities and considerable challenges in terms of theory and technology. Thus, a comprehensive summary with systematic analyses of anesthetic nanomedicines is urgently required. This review provides a comprehensive summary of the classification, properties, and research status of anesthetic nanomedicines, along with an exploration of their opportunities and challenges. In addition, future research directions and development prospects are discussed. It is hoped that researchers from diverse disciplines will collaborate to study anesthetic nanomedicines and develop them as a valuable anesthetic dosage form for clinical surgery.

Hyaluronic Acid-Based Nanosystems for CD44 Mediated Anti-Inflammatory and Antinociceptive Activity

The nervous and immune systems go hand in hand in causing inflammation and pain. However, the two are not mutually exclusive. While some diseases cause inflammation, others are caused by it. Macrophages play an important role in modulating inflammation to trigger neuropathic pain. Hyaluronic acid (HA) is a naturally occurring glycosaminoglycan that has a well-known ability to bind with the cluster of differentiation 44 (CD44) receptor on classically activated M1 macrophages. Resolving inflammation by varying the molecular weight of HA is a debated concept. HA-based drug delivery nanosystems such as nanohydrogels and nanoemulsions, targeting macrophages can be used to relieve pain and inflammation by loading antinociceptive drugs and enhancing the effect of anti-inflammatory drugs. This review will discuss the ongoing research on HA-based drug delivery nanosystems regarding their antinociceptive and anti-inflammatory effects.

Pain management with transdermal drug administration: A review

Pain management is an urgent issue to solve with complex mechanisms. Localized acute pain requires rapid and accurate delivery of drugs with less distribution in the blood circulation while chronic pain requires controlled release of drugs with long drug retention time. The transdermal route, a promising way with high patient compliance was known for painless delivery, long drug retention time, stable blood concentration, easily controlled dosage and release rate as well as the fewer side effects. This review presents transdermal route for pain management according to the different sites of action which drugs aim to reach, and illustrates different analgesic mechanisms, dosage forms, transdermal enhancements and clinical applications. In addition, the review concludes the difference of pain types and presents the future aims of pain management, thereby providing a reference for researches focusing on percutaneous analgesia.

Synthesis of nanocapsules blended polymeric hydrogel loaded with bupivacaine drug delivery system for local anesthetics and pain management

Local anesthetics are used clinically for the control of postoperative pain management. This study aimed to develop chitosan (CS) with genipin (GP) hydrogels as the hydrophilic lipid shell loaded poly(ε-caprolactone) (PC) nanocapsules as the hydrophobic polymeric core composites (CS-GP/PC) to deliver bupivacaine (BPV) for the prolongation of anesthesia and pain relief. The swelling ratio, in vitro degradation, and rheological properties enhancement of CS-GP/PC polymeric hydrogel. The incorporation of PC nanocapsules into CS-GP hydrogels was confirmed by SEM, FTIR, and XRD analysis. Scanning electron microscopy results demonstrated that the CS-GP hydrogels and CS-GP/PC polymeric hydrogels have a porous structure, the pore dimensions being non-uniform with diameters between 25 and 300 μm. The in vitro drug release profile of CS-GP/PC polymeric hydrogel has been achieved 99.2 ± 1.12% of BPV drug release in 36 h. Cellular viability was evaluated using the CCK-8 test on 3T3 fibroblast cells revealed that the obtained CS-GP/PC polymeric hydrogel with BPV exhibited no obvious cytotoxicity. The CS-GP/PC polymeric hydrogel loaded with BPV showed significant improvement in pain response compared to the control group animals for at least 7 days. When compared with BPV solution, CS-GP hydrogel and CS-GP/PC polymeric hydrogel improved the skin permeation of BPV 3-fold and 5-fold in 24 h, respectively. In vitro and in vivo results pointed out PC nanocapsules loaded CS-GP hydrogel can act as effective drug carriers, thus prolonging and enhancing the anesthetic effect of BPV. Histopathological results demonstrated the excellent biodegradability and biocompatibility of the BPV-loaded CS-GP/PC polymeric hydrogel system on 7, 14, and 21 days without neurotoxicity.

HIGHLIGHTS

Preparation and characterization of CS-GP/PC polymeric hydrogel system.

BPV-loaded CS-GP/PC exhibited prolonged in vitro release in PBS solution.

Cytotoxicity of BPV-loaded CS-GP/PC polymeric hydrogel against fibroblast (3T3) cells.

Development of CS-GP/PC a promising skin drug-delivery system for local anesthetic BPV.

A novel modified chitosan/collagen coated-gold nanoparticles for 5-fluorouracil delivery: Synthesis, characterization, in vitro drug release studies, anti-inflammatory activity and in vitro cytotoxicity assay

We report herein the development of the novel nanohybrids of gold nanoparticles reduced/stabilized/coated with collagen (AuNPs@collagen) in the first layer and subsequently modified with biotin-quat188-chitosan (Bi-QCS) in the outer layer for 5-fluorouracil (5-FU) delivery to improve cellular uptake and promote specific cell targeting of the nanocarrier. The fabrication of the layer-by-layer technique on the surface of gold nanoparticles (AuNPs) can overcome the limitation of poor drug loading capacity of the classic AuNPs from 64.67% to 87.46%. The AuNPs@collagen coated by the Bi-QCS exhibits strong electrostatic interactions between drug anion (5-FU) and amine groups of the modified chitosan as well as hydrogen bonding. Furthermore, the Bi-QCS-AuNPs@collagen demonstrated a significantly higher anti-inflammatory activity in RAW264.7 macrophage cell line. The Bi-QCS-AuNPs@collagen enhanced the activity of 5-FU approximately 3.3-fold (HeLa) and 6.2-fold (A549), compared to the free 5-Fluorouracil. According to these results, it is very promising that Bi-QCS-AuNPs@collagen can be used as an effective drug delivery carrier in the future.

Combination anesthetic therapy: co-delivery of ropivacaine and meloxicam using transcriptional transactivator peptide modified nanostructured lipid carriers in vitro and in vivo

Combination therapy combining two drugs in one modified drug delivery system is used to achieve synergistic analgesic effect, and bring effective control of pain management, especially postoperative pain management. In the present study, a combination of drug delivery technologies was utilized. Transcriptional transactivator (TAT) peptide modified, transdermal nanocarriers were designed to co-deliver ropivacaine (RVC) and meloxicam (MLX) and anticipated to achieve longer analgesic effect and lower side effect. TAT modified nanostructured lipid carriers (TAT-NLCs) were used to co-deliver RVC and MLX. RVC and MLX co-loaded TAT-NLCs (TAT-NLCs-RVC/MLX) were evaluated through in vitro skin permeation and in vivo treatment studies. NLCs-RVC/MLX showed uniform and spherical morphology, with a size of 133.4 ± 4.6 nm and a zeta potential of 20.6 ± 1.8 mV. The results illustrated the anesthetic pain relief ability of the present constructed system was significantly improved by the TAT modification through the enhanced skin permeation efficiency and the co-delivery of MLX along with RVC that improved pain management by reducing inflammation at the injured area. This study provides an efficient and facile method for preparing TAT-NLCs-RVC/MLX as a promising system to achieve synergistic analgesic effect.

Preparation of novel ropivacaine hydrochloride-loaded PLGA microspheres based on post-loading mode and efficacy evaluation

Low encapsulation efficiency of the drug usually exist in hydrophilic drug which was embedded by hydrophobic materials directly in traditional method. In order to solve this problem, a novel preparation strategy which called "post-loading mode" was innovatively designed in this study: ropivacaine hydrochloride (ROP), a hydrophilic drug used in the field of anesthesia and analgesia, was encapsulated into the pre-prepared porous Poly (lactic-co-glycolic acid) (PLGA) microspheres; the porous PLGA microspheres (PLGA-Ms) with self-healing characteristic were used to obtain ROP-PLGA-Ms (with particle size around were 38 µm), in which drug loading (DL) was 8.72%. A rat sciatic nerve block model was established to evaluate the efficacy of ROP-PLGA-Ms. Exparel®, a bupivacaine liposome suspension approved by the FDA, was defined as reference agents in this study. The results showed that the injection of ROP, Exparel®, and ROP-PLGA-Ms were injected to the peripheral sciatic nerve could lead to motor dysfunction and sensory nerve block unanimously, and the onset time was less than 10 min for all cases. In addition, in comparison with ROP injection and Exparel®, the nerve block time of ROP-PLGA-Ms was significantly prolonged (P < 0.05). Effective analgesia duration of ROP-PLGA-Ms was about 5 h, 2.5 and 1.7 folds longer than that of ROP injection and Exparel®, respectively. The rats in each group could recover eventually within 8 h after administration. H&E showed that no inflammatory reaction was observed at the injection location. Analysis of blood biochemistry showed an insignificant difference between the microsphere experimental group and the negative group, which further indicated the safety of microsphere bioformulation.

Recent advances in chitosan-based layer-by-layer biomaterials and their biomedical applications

In recent years, chitosan-based biomaterials have been continually and extensively researched by using layer-by-layer (LBL) assembly, due to their potentials in biomedicine. Various chitosan-based LBL materials have been newly developed and applied in different areas along with the development of technologies. This work reviews the recent advances of chitosan-based biomaterials produced by LBL assembly. Driving forces of LBL, for example electrostatic interactions, hydrogen bond as well as Schiff base linkage have been discussed. Various forms of chitosan-based LBL materials such as films/coatings, capsules and fibers have been reviewed. The applications of these biomaterials in the field of antimicrobial applications, drug delivery, wound dressings and tissue engineering have been comprehensively reviewed.

Enhancement of Skin Delivery of Drugs Using Proposome Depends on Drug Lipophilicity

The study aims to investigate the propylene glycol-based liposomes named 'proposomes' in enhancing skin permeation of drugs with different physicochemical properties. Ibuprofen, tofacitinib citrate, rhodamine B, and lidocaine were loaded into proposomes. These drug formulations were analyzed for particle size, zeta potential, polydispersity index, entrapment efficiency, and in vitro skin permeation. The confocal laser scanning microscopy was performed on skin treated with calcein and rhodamine B laden proposomes. The transdermal delivery relative to physicochemical properties of drugs such as logP, melting point, molecular weight, solubility, etc., were analyzed. We tested the safety of the proposomes using reconstructed human skin tissue equivalents, which were fabricated in-house. We also used human cadaver skin samples as a control. The proposomes had an average diameter of 128 to 148 nm. The drug's entrapment efficiencies were in the range of 42.9-52.7%, translating into the significant enhancement of drug permeation through the skin. The enhancement ratio was 1.4 to 4.0, and linearly correlated to logP, molecular weight, and melting point. Confocal imaging also showed higher skin permeation of calcein and rhodamine B in proposome than in solution. The proposome was found safe for skin application. The enhancement of skin delivery of drugs through proposomes was dependent on the lipophilicity of the drug. The entrapment efficiency was positively correlated with logP of the drug, which led to high drug absorption.

Dexmedetomidine and levobupivacaine co-loaded, transcriptional transactivator peptide modified nanostructured lipid carriers or lipid-polymer hybrid nanoparticles, which performed better for local anesthetic therapy?

Local anesthetics (LAs) have been widely applied in clinic for regional anesthesia, postoperative analgesia, and management of acute and chronic pain. Nanostructured lipid carriers (NLCs) and lipid–polymer hybrid nanoparticles (LPNs) are reported as good choices for LA therapy. Transactivated transcriptional activator (TAT) was reported as a modifier for the topical delivery of drugs. In the present study, TAT modified, levobupivacaine (LEV) and dexmedetomidine (DEX) co-delivered NLCs (TAT-LEV&DEX-NLCs, T-L&D-N) and LPNs (TAT-LEV&DEX-LPNs, T-L&D-L) were designed and compared for the LA therapy. T-L&D-L exhibited better efficiency in improving the skin permeation, analgesic time, and pain control intensity than T-L&D-N both in vitro and in vivo. On the other side, T-L&D-N also improved the therapeutic effect of drugs to a large extent. These two systems both exhibited superiority in some respects. TAT modified LPNs are more promising platform for the long-term local anesthesia.

Polyvinyl Alcohol/Hydroxyethylcellulose Containing Ethosomes as a Scaffold for Transdermal Drug Delivery Applications

This study aims to develop scaffold for transdermal drug delivery method (TDDM) using electrospinning technique from polyvinyl alcohol (PVA) and hydroxyethylcellulose (HEC). The fluorescein isothiocyanate (FITC) loaded on ethosomes (FITC@Eth) was used as a drug model. The prepared PVA/HEC/FITC@Eth scaffold was characterized via scanning electron microscope (SEM) that show morphology change by adding FITC@Eth. Also, Fourier transform infrared spectroscopy (FTIR), mechanical properties, X-ray diffraction (XRD), thermal gravimetric (TGA) analysis show that the addition of FITC@Eth to PVA/HEC does not change the scaffold properties. Franz diffusion cells were used for in vitro skin permeation experiments using rat dorsal skins. The FITC@Eth penetration was better than that of free FITC due to the presence of ethosome which enhance the potential skin targeting. In conclusion, the prepared PVA/HEC/FITC@Eth scaffold can serve as a promising transdermal scaffold for sustained FITC release.

Chemical and physical chitosan hydrogels as prospective carriers for drug delivery: a review

This review summarizes and discusses recent research progress in chemical and physical chitosan hydrogels for drug delivery.

Transferosomes as nanocarriers for drugs across the skin: Quality by design from lab to industrial scale

Transferosomes, also known as transfersomes, are ultradeformable vesicles for transdermal applications consisting of a lipid bilayer with phospholipids and an edge activator and an ethanol/aqueous core. Depending on the lipophilicity of the active substance, it can be encapsulated within the core or amongst the lipid bilayer. Compared to liposomes, transferosomes are able to reach intact deeper regions of the skin after topical administration delivering higher concentrations of active substances making them a successful drug delivery carrier for transdermal applications. Most transferosomes contain phosphatidylcholine (C18) as it is the most abundant lipid component of the cell membrane, and hence, it is highly tolerated for the skin, decreasing the risk of undesirable effects, such as hypersensitive reactions. The most common edge activators are surfactants such as sodium deoxycholate, Tween® 80 and Span® 80. Their chain length is optimal for intercalation within the C18 phospholipid bilayer. A wide variety of drugs has been successfully encapsulated within transferosomes such as phytocompounds like sinomenine or apigenin for rheumatoid arthritis and leukaemia respectively, small hydrophobic drugs but also macromolecules like insulin. The main factors to develop optimal transferosomal formulations (with high drug loading and nanometric size) are the optimal ratio between the main components as well as the critical process parameters for their manufacture. Application of quality by design (QbD), specifically design of experiments (DoE), is crucial to understand the interplay among all these factors not only during the preparation at lab scale but also in the scale-up process. Clinical trials of a licensed topical ketoprofen transferosomal gel have shown promising results in the alleviation of symptons in orthreothritis with non-severe skin and subcutaneous tissue disorders. However, the product was withdrawn from the market which probably was related to the higher cost of the medicine linked to the expensive manufacturing process required in the production of transferosomes compared to other conventional gel formulations. This example brings out the need for a careful formulation design to exploit the best properties of this drug delivery system as well as the development of manufacturing processes easily scalable at industrial level.

Topical anesthetic analgesic therapy using the combination of ropivacaine and dexmedetomidine: hyaluronic acid modified long-acting nanostructured lipid carriers containing a skin penetration enhancer

Purpose

Hyaluronic acid-poly(ethylene glycol)-distearoyl phosphoethanolamine (HA-PEG-DSPE) modified and tocopheryl polyethylene glycol 1000 succinate (TPGS) contained nanostructured lipid carriers (NLCs) were prepared loading ropivacaine and dexmedetomidine to improve the topical anesthetic analgesic anesthesia efficiency.

Methods

NLCs were prepared by the solvent diffusion method. The average particle size, zeta potential, release behavior, and cytotoxicity of the NLCs were tested. Ex vivo skin permeation was studied using a Franz diffusion cell mounted with depilated rat skin. Local anesthesia antinociceptive efficiency was evaluated by rat tail flick latency study in vivo.

Results

NLCs have sizes of about 100 nm, with negative zeta potentials. All the NLCs formulations were found to be significantly less cytotoxic than free drugs at equivalent concentrations. The cumulative amount of drugs penetrated through rat skin from NLCs was 2.0–4.7 folds higher than that of the drugs solution. The in vivo anesthesia antinociception study displayed that NLCs showed stronger and longer anesthesia antinociceptive effect when compared with single drugs loaded NLCs and drugs solution even at a lower dosage of drugs.

Conclusion

The results demonstrated that the HA modified, TPGS contained, dual drugs loaded NLCs could perform a synergistic effect and may reduce the amount of drugs, which can lower the toxicity of the system and at the meanwhile, increase the anesthesia antinociceptive efficiency.

Recent advances in polymer-based drug delivery systems for local anesthetics

Local anesthetics, which cause temporary loss of pain by inhibiting the transmission of nerve impulses, have been widely used in clinical practice. However, neurotoxicity and short half-lives have significantly limited their clinical applications. To overcome those barriers, numerous drug delivery systems (DDS) have been designed to encapsulate local anesthetic agents, so that large doses can be released slowly and provide analgesia over a prolonged period. So far, multiple classes of local anesthetic carriers have been investigated, with some of them already on the market. Among those, polymer-based delivery platforms are the most extensively explored, especially in the form of polymeric nanoparticle carriers. This review gives a specific focus on the most commonly used natural and synthetic polymers for local anesthetics delivery, owing to their excellent biocompatibility, biodegradability and versatility. State-of-the-art studies concerning such polymer delivery systems have been discussed in depth. We also highlight the impact of those delivery platforms as well as some key challenges that need to be overcome for their broader clinical applications. STATEMENT OF SIGNIFICANCE: Currently, local anesthetics have been widely used in clinically practices to prevent transmission of nerve impulses. However, the applications of anesthetics are greatly limited due to their neurotoxicity and short half-lives. Moreover, it is difficult to maintain frequent administrations which can cause poor compliance and serious consequences. Numerous drug delivery systems have been developed to solve those issues. In this review, we highlight the recent advances in polymer-based drug delivery systems for local anesthetics. The advantages as well as shortcomings for different types of polymer-based drug delivery systems are summarized in this paper. In the end, we also give prospects for future development of polymer drug delivery systems for anesthetics.

Synthesis and characterization of nanostructured lipid-poloxamer organogels for enhanced skin local anesthesia

The aim of this study was to synthesize a novel drug delivery system using organogels (ORGs) and characterize its physicochemical properties, in vitro and ex vivo permeation abilities, cytotoxicity and in vivo local anesthetic effects. The ORG formulations contained a mixture of oleic acid-lanolin (OA-LAN), poloxamer (PL407), and the commonly used local anesthetic lidocaine (LDC). The main focus was to evaluate the impact of LAN and PL407 concentrations on the ORG structural features and their biopharmaceutical performance. Results revealed that LDC, OA, and LAN incorporation separately shifted the systems transitions phase temperatures and modified the elastic/viscous moduli relationships (G'/G″ = ~15×). Additionally, the formulation with the highest concentrations of LAN and PL407 reduced the LDC flux from ~17 to 12 μg·cm^-2·h^-1 and the permeability coefficients from 1.2 to 0.62 cm·h^-1 through ex vivo skin. In vivo pharmacological evaluation showed that the ORG-based drug delivery system presented low cytotoxicity, increased and prolonged the local anesthetic effects compared to commercial alternatives. The data from this study indicate that ORG represent a promising new approach to effectively enhance the topical administration of local anesthetics.

Topical anesthesia therapy using lidocaine-loaded nanostructured lipid carriers: tocopheryl polyethylene glycol 1000 succinate-modified transdermal delivery system

Purpose

Transdermal drug delivery of local anesthetics using lipid nanoparticles could enhance lipophilic drugs permeation through the stratum corneum, improve drug diffusion to deeper skin, and exert good therapeutic effects. The purpose of this study was to engineer a Tocopheryl Polyethylene Glycol 1000 Succinate (TPGS)-modified cationic nanostructured lipid carriers (NLC) for the delivery of lidocaine (LID; TPGS/LID-NLC).

Materials and methods

TPGS/LID-NLC was prepared by solvent diffusion method. The particle size, polydispersity index, zeta potential, drug entrapment efficiency, drug loading, stability, drug release, and cytotoxicity were tested to evaluate the basic characters of NLC. In vitro skin permeation and in vivo anesthesia effect in an animal model were further investigated to determine the therapeutic efficiency of the system.

Results

TPGS/LID-NLC had a particle size of 167.6±4.3 nm, a zeta potential of +21.2±2.3 mV, an entrapment efficiency of 85.9%±3.1%, and a drug loading of 11.5%±0.9%. A sustained release pattern was achieved by TPGS/LID-NLC, with 81.2% of LID released at 72 hours. In vitro permeation study showed that the steady-state fluxes (J_ss), permeability coefficient (Kp), and cumulative drug permeation Q_n at 72 hours (Q₇₂) of TPGS/LID-NLC were 15.6±1.8 µg/cm²/hour, 10.3±0.9 cm/hour (×10⁻³), and 547.5±23.6 µg/cm², respectively, which were significantly higher than the nonmodified NLC and free drug groups. In vivo anesthesia effect of TPGS/LID-NLC was the most remarkable and long acting among the formulations tested, which could be concluded by the most considerable maximum possible effect from 10 to 120 minutes during the whole research.

Conclusion

The most prominent in vitro permeation efficiency and in vivo anesthetic effect of TPGS/LID-NLC could be the evidence that TPGS-modified NLC could function as a promising drug delivery system for prolonged and efficient local anesthetic therapy.

Hyaluronic acid-containing ethosomes as a potential carrier for transdermal drug delivery

A hyaluronic acid-containing ethosomes (HA-ES) as the transdermal drug delivery system was prepared in this work, and rhodamine B (RB) was used as a model drug to be encapsulated. The obtained HA-ES-RB was then characterized by the surface morphology, entrapment efficiency, drug loading and the stability. Results showed that the prepared HA-ES-RB was spherical and showed good dispersion as well as the stability, with a particle size of below 100 nm. The skin permeation experiments were carried out in vitro with the Franz diffusion cells and the rat dorsal skins were used. It was found that the penetration effect of HA-ES-RB was much better than that of ES-RB. The fluorescence microscopy image showed that HA-ES-RB penetrated into the deepest dermis. The excellent transdermic drug delivery effect of HA-ES-RB maybe attributed from its smaller size, hydration of hyaluronic acid as well as greater potential targeting to skin and skin appendages of liposomal carriers. Moreover, the HA-ES delivery system showed non-cytotoxicity to normal cells, indicating a good biocompatibility. This work provded a hyaluronic acid-containing ethosomes which can offer a quick, high efficient, safe and self-administered transdermal drug delivery system.

The history and progress of local anesthesia: multiple approaches to elongate the action

Analgesia and temporary inhibition of motor activity without interfering with central nervous function have been the essential merits of local anesthesia. Local anesthetics originated from cocaine have played a major role in local analgesia. However, the relatively short duration of action of local anesthetics has been a concern in intra- and post-operative analgesia. From the early age of modern local anesthesia, physicians and medical scientists had been struggling to control the active duration of local anesthetics. Such approach includes: development of long-acting local anesthetics, with physical tourniquet techniques, co-administration of other medicines such as vaso-constrictive agents or analgesics, development of mechanical devices to continuously or intermittently administer local anesthetics, and utilization of pharmaceutical drug delivery systems. In this review, the historical sequence of studies that have been performed in an effort to elongate the action of local anesthetics is presented, referring to epoch-making medical and scientific studies.

Insulin-loaded PLGA microspheres for glucose-responsive release

Porous poly(lactic-co-glycolic acid) (PLGA) microspheres were prepared, loaded with insulin, and then coated in poly(vinyl alcohol) (PVA) and a novel boronic acid-containing copolymer [poly(acrylamide phenyl boronic acid-co-N-vinylcaprolactam); p(AAPBA-co-NVCL)]. Multilayer microspheres were generated using a layer-by-layer approach depositing alternating coats of PVA and p(AAPBA-co-NVCL) on the PLGA surface, with the optimal system found to be that with eight alternating layers of each coating. The resultant material comprised spherical particles with a porous PLGA core and the pores covered in the coating layers. Insulin could successfully be loaded into the particles, with loading capacity and encapsulation efficiencies reaching 2.83 ± 0.15 and 82.6 ± 5.1% respectively, and was found to be present in the amorphous form. The insulin-loaded microspheres could regulate drug release in response to a changing concentration of glucose. In vitro and in vivo toxicology tests demonstrated that they are safe and have high biocompatibility. Using the multilayer microspheres to treat diabetic mice, we found they can effectively control blood sugar levels over at least 18 days, retaining their glucose-sensitive properties during this time. Therefore, the novel multilayer microspheres developed in this work have significant potential as smart drug-delivery systems for the treatment of diabetes.

Irinotecan and 5-fluorouracil-co-loaded, hyaluronic acid-modified layer-by-layer nanoparticles for targeted gastric carcinoma therapy

For targeted gastric carcinoma therapy, hyaluronic acid (HA)-modified layer-by-layer nanoparticles (NPs) are applied for improving anticancer treatment efficacy and reducing toxicity and side effects. The aim of this study was to develop HA-modified NPs for the co-loading of irinotecan (IRN) and 5-fluorouracil (5-FU). A novel polymer–chitosan (CH)–HA hybrid formulation (HA–CH–IRN/5-FU NPs) consisting of poly(d,l-lactide-co-glycolide) (PLGA) and IRN as the core, CH and 5-FU as a shell on the core and HA as the outmost layer was prepared. Its morphology, average size, zeta potential and drug encapsulation ability were evaluated. Human gastric carcinoma cells (MGC803 cells) and cancer-bearing mice were used for the testing of in vitro cytotoxicity and in vivo antitumor efficiency of NPs. HA–CH–IRN/5-FU NPs displayed enhanced antitumor activity in vitro and in vivo than non-modified NPs, single drug-loaded NPs and drugs solutions. The results demonstrate that HA–CH–IRN/5-FU NPs can achieve impressive antitumor activity and the novel targeted drug delivery system offers a promising strategy for the treatment of gastric cancer.