Facile design of lidocaine-loaded polymeric hydrogel to persuade effects of local anesthesia drug delivery system: complete in vitro and in vivo toxicity analyses

The Effects of Synthetic Polymers on the Release Patterns of Bupivacaine Hydrochloride from Sodium Hyaluronate Hydrogels

BACKGROUND

Using hydrogels for the controlled release of drugs is beneficial for patients, who then receive the proper dose of the medicinal substance. In addition, the formulation can provide more consistent drug absorption while reducing the frequency of dosing.

OBJECTIVES

The aim of this investigation is to propose a novel HA (sodium hyaluronate)-based hydrogel for intra-articular injection doped with synthetic polymers and incorporated with bupivacaine hydrochloride (Bu) as a local anesthetic. The other aim of this study is to reveal the effects of the formulation's ingredients on its viscosity and the relationship between the hydrogel's viscosity and drug release.

METHODS

First, HA-based hydrogels doped with synthetic polymers and incorporated with Bu were prepared. A study of the hydrogels' viscosities was performed using a rotational viscometer. Release tests were carried out by employing a paddle-over-disk apparatus following the USP/Ph.Eur guidelines. The drug concentrations in the acceptor fluid were analyzed spectrophotometrically.

RESULTS

It was found that the viscosity of the hydrogels doped with synthetic polymers was higher than the viscosity of the hydrogels made with only HA. The viscosity of the hydrogels doped with AX (ammonium acryloyldimethyltaurate/VP copolymer) was the highest, measuring 6750 ± 160 cP and 12623 ± 379 cP with and without Bu, respectively. The results of the kinetic experiment indicate that the Higuchi and Korsmeyer-Peppas models best described the drug release. Bu was released the most slowly from the formulation doped with AX. The release rate constants obtained from the Higuchi and Korsmeyer-Peppas models were kH = 4.4 ± 0.2 mg × min-1/2 and kK-P = 3.4 ± 0.2 × 10-2 min-N, respectively. The half-release time, calculated using the Higuchi model, was the longest for the formulation doped with AX, at 199.5 ± 17.6 min.

CONCLUSIONS

This indicates that the incorporation of AX into the hydrogel may prolong the drug dissolution. The hydrogel doped with AX was the optimal formulation for the controlled release of Bu.

Construction of bupivacaine-loaded gelatin-based hydrogel delivery system for sciatic nerve block in mice

Peripheral nerve blockade (PNB) is a common treatment to relieve postoperative pain. However, local anesthetics alone have a short duration of action and severe side effects during postoperative analgesia. In order to overcome these limitations, the present study reported an injectable hydrogel with a drug slow-release profile for regional nerve blockade. The injectable hydrogel was prepared by crosslinking with gelatin and NHS-PEG-NHS, which was degradable in the physiological environment and displayed sustainable release of anesthetics locally, thus improving the disadvantage of the high toxicity of local anesthetics. In this regard, we conducted a series of in vitro characterizations and proved that the hydrogel has a porous three-dimensional mesh structure with high drug loading capability, and sustainable drug release profile. And cytotoxicity experiments confirmed the good biocompatibility of the hydrogel. It was shown that using the animal sciatic nerve block model, the analgesic effect was greatly improved in vivo, and there was no obvious evidence of permanent inflammation or nerve damage in the block site's sections. This locally slow-release platform, combined with local anesthetics, is therefore a promising contender for long-acting analgesia.

Biopolymer-Based Hydrogel Incorporated with Naproxen Sodium and Lidocaine Hydrochloride for Controlled Drug Delivery

Sodium hyaluronate (HA) is a natural polysaccharide. This biopolymer occurs in many tissues of living organisms. The regenerating, nourishing, and moisturizing properties as well as the rheological properties of HA enable its application in the pharmaceutical industry as a carrier of medicinal substances. The aim of this work was to assess the release of naproxen sodium (Nap) in the presence of lidocaine hydrochloride (Lid) from the biopolymer-based hydrogels and to determine the respective kinetic parameters of this process. The possible interaction between the HA polysaccharide carrier and the selected drugs was also investigated. Three hydrogels containing Nap and Lid with different concentrations of the biopolymer were prepared. The release of Nap was studied by employing USP apparatus 5. The infrared study and differential scanning calorimetry analysis of physical mixtures and dried formulations were performed. The highest amount of Nap was released from the formulation with the lowest concentration of the biopolymer. The most representative kinetic model that described the dissolution of Nap was obtained through the Korsmeyer-Peppas equation. The release rate constants were in the range of 1.0 ± 0.1 × 10-2 min-n-1.7 ± 0.1 × 10-2 min-n. Lid did not influence the dissolution of Nap from the formulations tested; however, in the desiccated samples of assessed formulations, the interaction between the polysaccharide and both drugs was observed.

Recent Research Advances in Nano-Based Drug Delivery Systems for Local Anesthetics

From a clinical perspective, local anesthetics have rather widespread application in regional blockade for surgery, postoperative analgesia, acute/chronic pain control, and even cancer treatments. However, a number of disadvantages are associated with traditional local anesthetic agents as well as routine drug delivery administration ways, such as neurotoxicity, short half-time, and non-sustained release, thereby limiting their application in clinical practice. Successful characterization of drug delivery systems (DDSs) for individual local anesthetic agents can support to achieve more efficient drug release and prolonged duration of action with reduced systemic toxicity. Different types of DDSs involving various carriers have been examined, including micromaterials, nanomaterials, and cyclodextrin. Among them, nanotechnology-based delivery approaches have significantly developed in the last decade due to the low systemic toxicity and the greater efficacy of non-conventional local anesthetics. Multiple nanosized materials, including polymeric, lipid (solid lipid nanoparticles, nanostructured lipid carriers, and nanoemulsions), metallic, inorganic non-metallic, and hybrid nanoparticles, offer a safe, localized, and long-acting solution for pain management and tumor therapy. This review provides a brief synopsis of different nano-based DDSs for local anesthetics with variable sizes and structural morphology, such as nanocapsules and nanospheres. Recent original research utilizing nanotechnology-based delivery systems is particularly discussed, and the progress and strengths of these DDSs are highlighted. A specific focus of this review is the comparison of various nano-based DDSs for local anesthetics, which can offer additional indications for their further improvement. All in all, nano-based DDSs with unique advantages provide a novel direction for the development of safer and more effective local anesthetic formulations.

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.HIGHLIGHTSPreparation 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.

Fabrication of a controlled-release delivery system for relieving sciatica nerve pain using an ultrasound-responsive microcapsule

Lidocaine, a potent local anesthetic, is clinically used in nerve block and pain management. However, due to its short half-life, repeated administration is required. For this reason, here we designed and prepared a lidocaine-encapsulated polylactic acid-glycolic acid (Lidocaine@PLGA) microcapsule with ultrasound responsiveness to relieve the sciatica nerve pain. With a premixed membrane emulsification strategy, the fabricated lidocaine-embedded microcapsules possessed uniform particle size, good stability, injectability, and long-term sustained release both in vitro and in vivo. More importantly, Lidocaine@PLGA microcapsules had the function of ultrasonic responsive release, which made the drug release controllable with the effect of on-off administration. Our research showed that using ultrasound as a trigger switch could promote the rapid release of lidocaine from the microcapsules, achieving the dual effects of long-term sustained release and short-term ultrasound-triggered rapid release, which can enable the application of ultrasound-responsive Lidocaine@PLGA microcapsules to nerve root block and postoperative pain relief.

Graphene Oxide-Reinforced Alginate Hydrogel for Controlled Release of Local Anesthetics: Synthesis, Characterization, and Release Studies

In pain relief, lidocaine has gained more attention as a local anesthetic. However, there are several side effects that limit the use of local anesthetics. Therefore, it is hypothesized that a hydrogel system with facile design can be used for prolonged release of lidocaine. In this study, we developed a formulation comprises of sodium alginate (SA) and graphene oxide (GO) to prolong the release of lidocaine. The gelation was induced by physically crosslinking the alginate with Ca2+ ions. The formation of blank SA and GO-reinforced SA hydrogels was investigated with different concentration of Ca2+ ions. The controlled release of lidocaine hydrochloride (LH) on both hydrogel systems was studied in PBS solution. The GO-reinforced SA hydrogels exhibited more sustained release than SA hydrogels without GO. In vitro biocompatibility test in L929 fibroblast cells confirmed the non-toxic property of hydrogels. Furthermore, to prove the in-situ gelation and biodegradability of hydrogels the hydrogels were injected on mice model and confirmed the stable gel formation. The hydrogels implanted onto the subcutaneous tissue of hydrogels retained over one week. These results indicate that LH-loaded GO-reinforced SA hydrogel can be a potential biomaterial for controlled release of local anesthetics.

Yolk-like non-stoichiometric nickel sulfide-based Janus hydrogel photothermal film for enhanced solar-driven water evaporation and multi-media purification

Solar-driven interface water evaporation is a promising strategy for desalination and wastewater treatment. However, it remains a huge challenge to simultaneously achieve a high light-to-heat conversion efficiency (η) and multi-media evaporation applications. In this study, a highly efficient Janus hydrogel photothermal film was developed using yolk-like non-stoichiometric nickel sulfide (NiS_2-x) microspheres and agar hydrogel. The NiS_2-x immobilized in the agar hydrogel has full-spectrum absorption characteristics at 200-2500 nm, which can perform efficient light-to-heat conversion and regulate water transport channels. Additionally, the pure agar in the bottom can transport water effectively and avoid heat loss. By the pouring method, the Janus hydrogel film can be easily prepared into various shapes; hence, it can be adjusted depending on the environment in which it is used. The optimized Janus hydrogel film (Janus hydrogel-1) possessed good hydrophilicity and showed an excellent solar evaporation rate of 1.45 kg m^-2h^-1, and a high η of 97% under one-sun irradiation. Theoretical simulation results showed that the outstanding water evaporation performance of Janus hydrogel-1 was mainly due to its relatively free water transport channels. Janus hydrogel-1 can be used for water evaporation applications in various media, including seawater, heavy metal ion/organic wastewater, and domestic sewage. Our work highlights the great potential of Janus hydrogel-1 for realizing a highly effective solar energy-driven interface water evaporation and multi-media purification.