Evaluation of safety and operative time in tumescent-free robotic nipple-sparing mastectomy: a retrospective single-center cohort study.

Purpose: Tumescent in nipple-sparing mastectomy (NSM) has been reported to increase the risk of necrosis by impairing blood flow to the skin flap and nipple-areolar complex. At our institution, we introduced a tumescent-free robotic NSM using the da Vinci single-port system (Intuitive Surgical, Inc.). Methods: We conducted a retrospective analysis of patients who underwent tumescent-free robotic NSM between October 2020 and March 2023 at Asan Medical Center (Seoul, Korea). Clinicopathological characteristics, adverse events, and operative time were evaluated. Results: During the study period, 118 patients underwent tumescent-free robotic NSM. Thirty-one patients (26.3%) experienced an adverse event. Five patients (4.2%) were classified as grade III based on the Clavien-Dindo classification and required surgery. The mean total operative time was 467 minutes for autologous tissue reconstruction (n = 49) and 252 minutes for implants (n = 69). No correlation was found between the cumulative number of surgical cases and the breast operative time (P = 0.30, 0.52, 0.59 for surgeons A, B, C) for the 3 surgeons. However, a significant linear relationship (P < 0.001) was observed, with the operative time increasing by 13 minutes for every 100-g increase in specimen weight. Conclusion: Tumescent-free robotic NSM is a safe procedure with a feasible operative time and few adverse events.

Adding Dexmedetomidine to Intra-articular Local Anesthetics Results in Prolonged Analgesia after Knee Arthroscopy: A Systematic Review and Meta-Analysis.

PURPOSE: This systematic review and meta-analysis aims to assess the efficacy and safety of dexmedetomidine as an adjuvant to intra-articular (IA) injections of local anesthetics (LA) in adult patients undergoing knee arthroscopy. METHODS: We searched MEDLINE, Embase, and Cochrane Library for randomized controlled trials (RCTs) comparing IA dexmedetomidine plus LA versus LA alone for knee arthroscopy in adults. We used the DerSimonian and Laird random-effects model for all outcomes, and conducted a sensitivity analysis with the leave-one-out method, as well as a subgroup analysis for the type of LA. We used R version 4.1.2 for all statistical analyses. RESULTS: We included 16 RCT encompassing 799 patients, of whom 49.8% received IA dexmedetomidine. In the pooled analysis, time to first analgesia rescue was prolonged in almost 4 hours with the use of dexmedetomidine (MD 229 min; p<0.001). We found statistically significant differences favoring dexmedetomidine in pain scores at rest and movement throughout the first 2, 6, 12 and 24 hours postoperatively (p<0.001). Although the mean difference (MD) ranged from -0.3 to -0.9 cm, corresponding to a 3 to 9% reduction in pain scores, this change is not clinically significant when compared to the minimal clinically important difference (MCID). Additionally, the intervention group showed a statistically significant reduction in cumulative opioid consumption over 24 hours (MD -4.5 mg; p<0.001). However, this reduction did not meet the threshold for the MCID. There was no difference between groups on the incidence of hypotension (p=0.190), bradycardia (p=0.430) and postoperative nausea and vomiting (p=0.550). CONCLUSIONS: Adding dexmedetomidine to LA in IA injections for knee arthroscopy significantly extended analgesia duration. Additionally, it lowered pain scores and opioid use, although these effects did not reach the MCID. Furthermore, this addition did not increase the risk of adverse events.

Foot Drop Following a Popliteal Sciatic Nerve Block with Ropivacaine, A Case Report and Literature Review.

Although peripheral nerve blocks are deemed very safe, a significant number of patients for whom this anesthetic technique may be particularly appealing to apply may present with preexisting peripheral neuropathies, putting them at risk for further nerve damage. We present a case with a 74-year-old male with several risk factors for peripheral neuropathy who developed a foot drop following a popliteal sciatic nerve block with ropivacaine. We suggest that the vasoconstrictive properties of ropivacaine may have contributed to a preexisting neuronal ischemia, thus further damaging an already compromised nerve.

Topical Ophthalmic Anesthetics for CornealAbrasions: Findings from a Cochrane SystematicReview and Meta-Analysis.

Background: Despite potential benefit, outpatient use of topical ophthalmic anesthetics can result in poor healing, infection, scar, and blindness. An unbiased analysis of randomized controlled trials (RCTs) is needed to examine their effectiveness and safety compared with placebo or other treatments for corneal abrasions. Methods: Cochrane Central Register of Controlled Trials, MEDLINE, Embase.com, Latin American and Caribbean Health Sciences, ClinicalTrials.gov, and the World Health Organization International Clinical Trials Registry Platform were searched on February 10, 2023, without restriction on language or publication date. Results: Systematic review and meta-analysis of nine RCTs describing 314 participants with post-traumatic abrasions and 242 participants with post-surgical abrasions, with a median study length of 7 days (interquartile range, 7-14), show no evidence of a difference in pain control between anesthetics and placebo at 24 hours in post-trauma cases. Self-reported pain at 24 hours is reduced with anesthetics plus topical nonsteroid anti-inflammatory drug in post-surgical participants (mean difference [MD], -5.72 on a 10-point scale; 95% CI, -7.35 to -4.09; 1 RCT; 30 participants) and at 48 hours with anesthetics alone in post-trauma participants (MD, -5.68; 95% CI, -6.38 to -4.98; 1 RCT; 111 participants). Anesthetics are associated with 37% increased risk of non-healing defects (risk ratio, 1.37; 95% CI, 0.78 to 2.42; 3 RCTs; 221 post-trauma participants). All evidence is of very low certainty. Over 50% of trials have an overall high risk of bias. Conclusions: Available evidence is insufficient to support outpatient use of topical anesthetics for corneal abrasions with respect to pain, re-epithelialization, and complication risk.

Development of ropivacaine hydrochloride-loaded dissolving microneedles as a local anesthetic agent: A proof-of-concept.

Ropivacaine hydrochloride (RPL) is a local anesthetic agent that has been widely used for the treatment of pain during or after surgery. However, this drug is only available in parenteral dosage form and may contribute to the infiltration of RPL into the plasma, causing some undesirable side effects. Intradermal delivery of RPL using dissolving microneedles may become a promising strategy to deliver such drugs into the skin. This research aimed to develop RPL-loaded dissolving microneedles (DMN-RPLs) as a proof of the concept of intradermal delivery of a local anesthetic. The DMN-RPLs were fabricated using either centrifugation or air-pressurized chamber methods. Several polymers, such as poly(vinyl pyrrolidone) (PVP), poly(vinyl alcohol) (PVA), and sodium hyaluronate (SH), were utilized for manufacturing the DMN-RPLs. The prepared DMN-RPLs were assessed for their thermal properties, chemical bonds, mechanical strength, insertion ability, skin-dissolution study, and drug content. Furthermore, in-skin deposition and dermatokinetic studies were also performed. The results showed that F9 (30 % w/w PVP-4 % w/w SH) and F10 (30 % w/w PVP-5 % w/w PVA) containing 5 % w/w of RPL were the most promising formulations, as shown by their needle height reduction (<10 %) and insertion depth (∼400 µm). Both formulations were also able to deliver more than 60 % of the RPL contained in the DMNs into the epidermis, dermis, and receiver compartment. This study, for the first time, has provided a proof concept to deliver RPL as a local anesthetic using DMNs and the intradermal route, aiming to minimize pain and discomfort during administration and improve the patient's experience.

Sequential administration of peripheral nerve blocks and onabotulinumtoxinA for the treatment of chronic migraine and other headache disorders-A retrospective tolerability and safety study.

OBJECTIVE: To determine the tolerability and safety of concurrent peripheral nerve blocks and onabotulinumtoxinA treatment during a single outpatient clinic procedure visit. BACKGROUND: Procedural interventions are available for the treatment of headache disorders. OnabotulinumtoxinA and peripheral nerve blocks are used as alternatives or in addition to oral therapies to reduce the frequency and intensity of migraine attacks. There is currently a lack of safety data focusing on the sequential administration of local anesthetic via peripheral nerve blocks and onabotulinumtoxinA during a single clinical encounter for the treatment of headache. The primary aim of the study was to determine the safety and tolerability of concurrent peripheral nerve blockade and onabotulinumtoxinA injections during a single outpatient clinic procedure visit. We hypothesized that the dual intervention would be safe and well tolerated by patients with chronic migraine and other headache disorders. METHODS: A retrospective chart review was performed using clinical data from patients seen by multiple providers over a 16-month timeframe at one outpatient headache clinic. Patients were identified by procedure codes and those receiving peripheral nerve block(s) and onabotulinumtoxinA injections during a single encounter within the study period were eligible for inclusion. Inclusion criteria were (1) patients 18 years and older who were (2) receiving both peripheral nerve blocks and onabotulinumtoxinA injections for the treatment of chronic migraine. Patients were excluded if they were under age 18, received their procedure outside of the clinic (emergency room, inpatient ward), or were receiving sphenopalatine ganglion blocks. Age- and sex-matched patients who received one procedure, either peripheral nerve blocks or onabotulinumtoxinA, were used for control. The primary outcome of this safety study was the number of adverse events that occurred in the dual intervention group compared to the single intervention control arms. Information regarding adverse events was gathered via retrospective chart review. If an adverse event was recorded, it was then graded by the reviewer utilizing the Common Terminology Criteria for Adverse Events ranging from Grade 1 Mild Event to Grade 5 Death. Additionally, it was noted whether the adverse event led to treatment discontinuation. RESULTS: In total, 375 patients were considered eligible for inclusion in the study. After age and sex matching of controls, 131 patients receiving dual intervention were able to be compared to 131 patients receiving onabotulinumtoxinA alone and 104 patients receiving dual intervention were able to be compared to 104 patients receiving peripheral nerve block(s) alone. The primary endpoint analysis showed no significant difference in total adverse events between dual intervention compared to nerve blocks alone or onabotulinumtoxinA alone. The number of adverse events that led to treatment discontinuation approached but did not reach statistical significance for those receiving dual intervention versus onabotulinumtoxinA alone in the number of adverse events that led to treatment termination (4.6%, 6/131 vs. 0.8%, 1/131, p = 0.065); however, the number of patients who discontinued therapy was not significantly different between those groups (2.3%, 3/131 vs. 0.8%, 1/131; p = 0.314; odds ratio 0.3 [0-3.2]; p = 0.338). CONCLUSIONS: In this retrospective chart review, there was no significant difference in adverse events or therapy discontinuation between patients receiving sequential peripheral nerve block(s) and onabotulinumtoxinA injections versus those receiving either peripheral nerve block(s) or onabotulinumtoxinA injections alone. As a result, we concluded that the combination procedure is likely safe and well tolerated in routine clinical practice.

Local Anesthetics, Local Anesthetic Systemic Toxicity (LAST), and Liposomal Bupivacaine.

Local anesthetics have played a vital role in the multimodal analgesia approach to patient care by decreasing the use of perioperative opioids, enhancing patient satisfaction, decreasing the incidence of postoperative nausea and vomiting, decreasing the length of hospital stay, and reducing the risk of chronic postsurgical pain. The opioid-reduced anesthetic management for perioperative analgesia has been largely successful with the use of local anesthetics during procedures such as peripheral nerve blocks and neuraxial analgesia. It is important that practitioners who use local anesthetics are aware of the risk factors, presentation, and management of local anesthetic systemic toxicity (LAST).

Role of mitochondrial DNA level in epidural-related maternal fever: a single-centre, observational, pilot study.

INTRODUCTION: Epidural analgesia has been associated with intrapartum maternal fever development. Epidural-related maternal fever (ERMF) is believed to be based on a non-infectious inflammatory reaction. Circulating cell-free mitochondrial deoxyribonucleic acid (mtDNA) is one of the possible triggers of sterile inflammatory processes; however, a connection has not been investigated so far. Therefore, this study aimed to investigate cell-free mtDNA alterations in women in labour with ERMF in comparison with non-febrile women. MATERIAL AND METHODS: A total of 60 women in labour were assessed for maternal temperature every 4 h and blood samples were obtained at the beginning and after delivery. Depending on the analgesia and the development of fever (axillary temperature ≥ 37.5 °C), the women were allocated either to the group of no epidural analgesia (n = 17), to epidural analgesia no fever (n = 34) or to ERMF (n = 9). Circulating cell-free mtDNA was analysed in the maternal plasma for the primary outcome whereas secondary outcomes include the evaluation of inflammatory cytokine release, as well as placental inflammatory signs. RESULTS: Of the women with epidural analgesia, 20% (n = 9) developed ERMF and demonstrated a decrease of circulating mtDNA levels during labour (p = 0.04), but a trend towards higher free nuclear DNA. Furthermore, women with maternal pyrexia showed a 1.5 fold increased level of Interleukin-6 during labour. A correlation was found between premature rupture of membranes and ERMF. CONCLUSIONS: The pilot trial revealed an evident obstetric anaesthesia phenomenon of maternal fever due to epidural analgesia in 20% of women in labour, demonstrating counterregulated free mtDNA and nDNA. Further work is urgently required to understand the connections between the ERMF occurrence and circulating cell-free mtDNA as a potential source of sterile inflammation. TRIAL REGISTRATION: NCT0405223 on clinicaltrials.gov (registered on 25/07/2019).

Local anesthetic delivery systems for the management of postoperative pain.

Postoperative pain (POP) is a major clinical challenge. Local anesthetics (LAs), including amide-type LAs, ester-type LAs, and other potential ion-channel blockers, are emerging as drugs for POP management because of their effectiveness and affordability. However, LAs typically exhibit short durations of action and prolonging the duration by increasing their dosage or concentration may increase the risk of motor block or systemic local anesthetic toxicity. In addition, techniques using LAs, such as intrathecal infusion, require professional operation and are prone to catheter displacement, dislodgement, infection, and nerve damage. With the development of materials science and nanotechnology, various LAs delivery systems have been developed to compensate for these disadvantages. Numerous delivery systems have been designed to continuously release a safe dose in a single administration to ensure minimal systemic toxicity and prolong pain relief. LAs delivery systems can also be designed to control the duration and intensity of analgesia according to changes in the external trigger conditions, achieve on-demand analgesia, and significantly improve pain relief and patient satisfaction. In this review, we summarize POP pathways, animal models and methods for POP testing, and highlight LAs delivery systems for POP management. STATEMENT OF SIGNIFICANCE: Postoperative pain (POP) is a major clinical challenge. Local anesthetics (LAs) are emerging as drugs for POP management because of their effectiveness and affordability. However, they exhibit short durations and toxicity. Various LAs delivery systems have been developed to compensate for these disadvantages. They have been designed to continuously release a safe dose in a single administration to ensure minimal toxicity and prolong pain relief. LAs delivery systems can also be designed to control the duration and intensity of analgesia to achieve on-demand analgesia, and significantly improve pain relief and patient satisfaction. In this paper, we summarize POP pathways, animal models, and methods for POP testing and highlight LAs delivery systems for POP management.

AG-920 (Articaine) Ophthalmic Solution: A Masked, Active-Controlled Evaluation of Its Local Anesthetic Efficacy and Safety in Pediatric Patients.

Purpose: The safety and efficacy of a novel topical ocular anesthetic (AG-920 sterile ophthalmic solution, 8%) was previously evaluated in adults. For both clinical and regulatory purposes, this new agent was evaluated in children. Methods: This was a Phase 3, randomized, active-controlled, single-masked, parallel-group design study in healthy pediatric subjects performed at a private practice retina clinic in the United States. The safety and anesthetic efficacy of AG-920 was compared with proparacaine hydrochloride ophthalmic solution 0.5% in 60 children undergoing ophthalmic examinations. The primary efficacy endpoint was whether the investigator was able to perform the eye examination. Results: In all subjects in each treatment group, the investigator was able to perform the eye examination without additional local anesthetic. There were no adverse events reported in this study. In both the study eye and fellow eye, there were no notable changes after dosing, and both treatment groups were similar. All external eye exams in all subjects in both treatment groups were normal. Conclusions: In this pediatric population aged 7 months to >11 years, AG-920 was therapeutically equivalent to marketed proparacaine with respect to having an ophthalmic examination performed without needing additional local anesthetic. Further, AG-920 was well tolerated, and there were no clinically significant safety findings.

Local anesthetics inhibit muscarinic acetylcholine receptor-mediated calcium responses and the recruitment of ß-arrestin in HSY human parotid cells.

OBJECTIVES: Local anesthetics act on G protein-coupled receptors (GPCRs); thus, their potential as allosteric modulators of GPCRs has attracted attention. Intracellular signaling via GPCRs involves both G-protein- and ß-arrestin-mediated pathways. To determine the effects of local anesthetics on muscarinic acetylcholine receptors (mAChR), a family of GPCRs, we analyzed the effects of local anesthetics on mAChR-mediated Ca2+ responses and formation of receptor-ß-arrestin complexes in the HSY human parotid cell line. METHODS: Ca2+ responses were monitored by fura-2 spectrofluorimetry. Ligand-induced interactions between mAChR and ß-arrestin were examined using a ß-arrestin GPCR assay kit. RESULTS: Lidocaine reduced mAChR-mediated Ca2+ responses but did not change the intracellular Ca2+ concentration in non-stimulated cells. The membrane-impermeant lidocaine analog QX314 and procaine inhibited mAChR-mediated Ca2+ responses, with EC50 values of 48.0 and 20.4 µM, respectively, for 50 µM carbachol-stimulated Ca2+ responses. In the absence of extracellular Ca2+, the pretreatment of cells with QX314 reduced carbachol-induced Ca2+ release, indicating that QX314 reduced Ca2+ release from intracellular stores. Lidocaine and QX314 did not affect store-operated Ca2+ entry as they did not alter the thapsigargin-induced Ca2+ response. QX314 and procaine reduced the carbachol-mediated recruitment of ß-arrestin, and administration of procaine suppressed pilocarpine-induced salivary secretion in mice. CONCLUSION: Local anesthetics, including QX314, act on mAChR to reduce carbachol-induced Ca2+ release from intracellular stores and the recruitment of ß-arrestin. These findings support the notion that local anesthetics and their derivatives are starting points for the development of functional allosteric modulators of mAChR.

Voltage-Gated Ion Channels: Structure, Pharmacology and Photopharmacology.

Voltage-gated ion channels are transmembrane proteins responsible for the generation and propagation of action potentials in excitable cells. Over the last decade, advancements have enabled the elucidation of crystal structures of ion channels. This progress in structural understanding, particularly in identifying the binding sites of local anesthetics, opens avenues for the design of novel compounds capable of modulating ion conduction. However, many traditional drugs lack selectivity and come with adverse side effects. The emergence of photopharmacology has provided an orthogonal way of controlling the activity of compounds, enabling the regulation of ion conduction with light. In this review, we explore the central pore region of voltage-gated sodium and potassium channels, providing insights from both structural and pharmacological perspectives. We discuss the different binding modes of synthetic compounds that can physically occlude the pore and, therefore, block ion conduction. Moreover, we examine recent advances in the photopharmacology of voltage-gated ion channels, introducing molecular approaches aimed at controlling their activity by using photosensitive drugs.

Neutrophils and Anesthetic Drugs: Implications in Onco-Anesthesia.

Apart from being a significant line of defense in the host defense system, neutrophils have many immunological functions. Although there are not many publications that accurately present the functions of neutrophils in relation to oncological pathology, their activity and implications have been studied a lot recently. This review aims to extensively describe neutrophils functions'; their clinical implications, especially in tumor pathology; the value of clinical markers related to neutrophils; and the implications of neutrophils in onco-anesthesia. This review also aims to describe current evidence on the influence of anesthetic drugs on neutrophils' functions and their potential influence on perioperative outcomes.

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-ß-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.

The minimum effective concentration (MEC90) of bupivacaine for an ultrasound-guided suprainguinal fascia iliaca compartment block for analgesia in knee surgery: a dose-finding study.

BACKGROUND: In recent years, the suprainguinal fascia iliaca compartment block (SFICB) has become more common in clinical practice. This assessor-blinded dose-finding study aimed to determine the minimum effective concentration (MEC90, MEC95) of bupivacaine for a single-injection SFICB in patients undergoing arthroscopic anterior cruciate ligament repair. METHODS: This prospective study was conducted at a tertiary hospital (postoperative recovery room and ward). The SFICB was performed as a postsurgical intervention after spinal anesthesia. Seventy patients were allocated using the biased-coin design up-and-down sequential method. The ultrasound-guided SFICB was performed using different bupivacaine concentrations, and standard multimodal analgesia was administered to all patients. Block success was defined as the absence of pain or presence of only tactile sensation during the pinprick test conducted on the anterior and lateral regions of the mid-thigh six hours postoperatively. RESULTS: According to isotonic regression and bootstrap CIs, the MEC90 value of bupivacaine for a successful SFICB was 0.123% (95% CI [0.098, 0.191]) and the MEC95 value was 0.188% (95% CI [0.113, 0.223]). CONCLUSIONS: Our study showed that the MEC90 and MEC95 values for bupivacaine administered via an SFICB for analgesia were 0.123% and 0.188%, respectively. One advantage of using lower concentrations of bupivacaine is the associated reduction in quadriceps weakness.

Trial watch: local anesthetics in cancer therapy.

Preclinical evidence indicates potent antitumor properties of local anesthetics. Numerous underlying mechanisms explaining such anticancer effects have been identified, suggesting direct cytotoxic as well as indirect immunemediated effects that together reduce the proliferative, invasive and migratory potential of malignant cells. Although some retrospective and correlative studies support these findings, prospective randomized controlled trials have not yet fully confirmed the antineoplastic activity of local anesthetics, likely due to the intricate methodology required for mitigating confounding factors. This trial watch aims at compiling all published preclinical and clinical research, along with completed and ongoing trials, that explore the potential antitumor effects of local anesthetics.

Knowledge, Attitudes and Practices Regarding Use of Local Anaesthetics Among Non-Anaesthesia Healthcare Professionals at Mulago National Referral Hospital.

Introduction: Local anaesthetics (LA) are commonly used in dental and surgical emergency wards by both anaesthesia professionals and non-anaesthesia professionals. Anecdotal evidence shows that non-anaesthesia health-care professionals do not monitor vital signs during the use of local anaesthesia, and there are no standard hospital guidelines on the use of LA and management of LA toxicity by non-anaesthesia professionals. Purpose: This study sought to assess the knowledge, attitudes and practices regarding local anaesthetic use among non-anaesthesia health-care professionals at Mulago National Referral Hospital. Patients and Methods: This was a cross-sectional study that utilized a quantitative research approach. The sample size of the study was 43 non-anaesthesia healthcare professionals from the casualty and surgical outpatient wards and Mulago dental ward. Data was collected using a questionnaire and analyzed using STATA 15. Results: Overall, 66.67% of the Specialist, 76.47% of the senior house officers, 100% of medical officers, and 80% of the clinical orthopedic house officers had unsatisfactory levels of knowledge in Mulago casualty and surgical outpatient wards. 20% of the specialist and 16.67% of the senior house officers had unsatisfactory levels of knowledge in Mulago dental ward. 87.5% of the non-anaesthesia health-care professionals do not give a test dose on a routine basis in Mulago casualty and surgical outpatient wards. A total of 63.64% of the non-anaesthesia healthcare professionals in Mulago dental ward do not sterilize the site of injection. Conclusion: Non-anaesthesia health-care professionals had unsatisfactory levels of knowledge, somewhat good practices, and negative attitudes toward LA use.

Targeted local anesthesia: a novel slow-release Fe3O4-lidocaine-PLGA microsphere endowed with a magnetic targeting function.

PURPOSE: Lidocaine microspheres can prolong the analgesic time to 24-48 h, which still cannot meet the need of postoperative analgesia lasting more than 3 days. Therefore, we added Fe3O4 to the lidocaine microspheres and used an applied magnetic field to attract Fe3O4 to fix the microspheres around the target nerves, reducing the diffusion of magnetic lidocaine microspheres to the surrounding tissues and prolonging the analgesic time. METHODS: Fe3O4-lidocaine-PLGA microspheres were prepared by the complex-emulsion volatilization method to characterize and study the release properties in vitro. The neural anchoring properties and in vivo morphology of the drug were obtained by magnetic resonance imaging. The nerve blocking effect and analgesic effect of magnetic lidocaine microspheres were evaluated by animal experiments. RESULTS: The mean diameter of magnetically responsive lidocaine microspheres: 9.04 ± 3.23 µm. The encapsulation and drug loading of the microspheres were 46.18 ± 3.26% and 6.02 ± 1.87%, respectively. Magnetic resonance imaging showed good imaging of Fe3O4-Lidocain-PLGA microspheres, a drug-carrying model that slowed down the diffusion of the microspheres in the presence of an applied magnetic field. Animal experiments demonstrated that this preparation had a significantly prolonged nerve block, analgesic effect, and a nerve anchoring function. CONCLUSION: Magnetically responsive lidocaine microspheres can prolong analgesia by slowly releasing lidocaine, which can be immobilized around the nerve by a magnetic field on the body surface, avoiding premature diffusion of the microspheres to surrounding tissues and improving drug targeting.