Bupivacaine extended-release liposome injection for prolonged postsurgical analgesia in patients undergoing hemorrhoidectomy: a multicenter, randomized, double-blind, placebo-controlled trial

Does Liposomal Bupivacaine Reduce Postoperative Pain Following Third Molar Extractions? A Double-Blinded Randomized Controlled Trial

BACKGROUND

Liposomal bupivacaine (LB) is a long-lasting local anesthetic providing analgesia for several days. The current literature examining the efficacy of LB in pain management following third molar extractions remains unclear.

PURPOSE

The purpose of this study was to compare postoperative pain management between LB and standard bupivacaine (SB) in mandibular third molar extractions.

STUDY DESIGN

A double-blinded randomized controlled trial of subjects undergoing bilateral mandibular third molar extractions at our institution from 2022 to 2024 was conducted using a split-mouth study design. Subjects were excluded if they received additional mandibular teeth extractions, were unable to complete the questionnaire, or had medical contraindications.

PREDICTOR VARIABLE

The predictor variable was postsurgical local anesthetic agent, and the sides of mouth were randomly assigned to LB or SB.

MAIN OUTCOME VARIABLE(S)

Primary outcome was postoperative pain on a 10-point numerical rating scale (NRS), and the mean cumulative pain rating via area under the curve (AUC) analysis. Secondary outcomes were adverse events and ibuprofen or acetaminophen consumption.

COVARIATES

Demographics, procedure time, preoperative and perioperative local anesthetics used, and procedural difficulty coded as nonsurgical or surgical were collected.

ANALYSES

We used mixed-effects models to compare the NRS scores during each time period and paired t-tests to compare AUC values. Statistical tests included 95% CIs with alpha = 0.05.

RESULTS

The study sample included 72 subjects (mean age 25.8, SD: 9). Pain was lower in the LB versus SB group on surgery day (NRS difference -0.75; P = .002) until the morning of postoperative day 2 (-0.68, P = .003). When limiting the analysis to bilateral surgical extractions, it was statistically significant until the morning of postoperative day 3 (-0.61, P = .02). AUC analysis showed cumulative pain reduction for the LB group in comparison to the SB group through all 4 postoperative days for the overall cohort (average AUC0-96 difference 93.5, P = .005), with a similar effect for bilateral surgical extractions (101.88, P = .006).

CONCLUSION

LB modestly reduces pain following third molar extractions, with this difference more pronounced following surgical extractions. This suggests that LB may be more beneficial in complex extractions and greater pain-inducing surgeries.

Bupivacaine Reduces the Viability of SH-SY5Y Cells and Promotes Apoptosis by the Inhibition of Akt Signaling Pathway

Bupivacaine (BUP) is a commonly used local anesthetic, while SH-SY5Y cells are a human neuroblastoma cell line frequently employed in research on neurotoxicity and neuroprotective mechanisms. To assess the neurotoxic effects of BUP on SH-SY5Y cells and the role of threonine-serine protein kinase B (Akt) signaling in BUP-induced nerve injury. SH-SY5Y cells were divided into three groups: the control group (Control), BUP group, and BUP + SC79 group. Cell viability was assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, the level of reactive oxygen species (ROS) in cells was detected using the dihydroethidium fluorescence probe method, and changes in mitochondrial membrane potential were detected by flow cytometry, while BUP-induced apoptosis was evaluated by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining. The effects of BUP on Bax, Bcl-2, Caspase-3, Caspase-9, Akt and phosphorylated Akt (p-Akt) were analyzed by Western blot (WB). Compared with the control group, the BUP group and the BUP + SC79 group showed significantly reduced cell viability, significantly increased apoptosis, significantly elevated ROS levels, significantly decreased JC-1 polymer/monomer ratio, significantly increased protein levels of Bax, caspase-3, caspase-9, Akt, and p-Akt, and significantly decreased Bcl-2 protein levels (P < 0.05). However, compared with the BUP group, the BUP + SC79 group exhibited significantly increased cell viability (P = 0.022), significantly reduced apoptosis rate (P = 0.017), significantly decreased ROS levels (P = 0.015), significantly increased JC-1 polymer/monomer ratio (P = 0.024), significantly reduced protein levels of Bax, caspase-3, caspase-9, Akt, and p-Akt (P = 0.033, 0.028, 0.030, 0.035, and 0.005, respectively), and significantly increased Bcl-2 protein levels (P = 0.024). BUP can reduce the viability of SH-SY5Y cells and promote apoptosis, which may be related to its inhibitory effect on Akt protein activity.

The Use of Liposomal Bupivacaine for Pain Control After Shoulder Surgery: A Systematic Review and Meta-analysis

BACKGROUND

Liposomal bupivacaine (LB) is a relatively novel anesthetic agent used in the management of postoperative pain in patients who have undergone shoulder surgery.

PURPOSE

To explore the literature on LB in the setting of shoulder surgery and assess its efficacy and utility in managing postoperative pain.

STUDY DESIGN

Systematic review and meta-analysis; Level of evidence, 1.

METHODS

PubMed, Cochrane, and Google Scholar (pp 1-20) were searched for articles published up to November 2023. Inclusion criteria consisted of randomized controlled trials comparing anesthetic modalities using LB with other anesthetic modalities using alternative drugs in patients who underwent shoulder surgery. Complications, pain levels in the first 24 hours postoperatively, and opioid consumption intraoperatively and in the first, second, and third 24 hours postoperatively were assessed.

RESULTS

A total of 15 randomized controlled trials were included in the meta-analysis. In 4 studies comparing periarticular injections of LB (196 patients) with nerve blocks of other anesthetic agents (201 patients), there was no significant difference in pain levels (P = .74) and complication rates (P = .37); however, intraoperative opioid consumption was significantly greater in patients with periarticular injections of LB (P = .005). In 3 studies comparing single-injection LB nerve blocks (83 patients) with interscalene nerve block catheters (102 patients) and in 8 studies comparing single-injection LB nerve blocks (311 patients) with other nerve blocks (308 patients), single-injection LB nerve blocks demonstrated clinical superiority. Single-injection LB nerve blocks resulted in significantly lower pain levels and lower opioid consumption in the first, second, and third 24 hours postoperatively compared with other single-injection nerve blocks and both single-injection nerve blocks and interscalene catheters combined.

CONCLUSION

LB is a promising anesthetic component with efficacy in providing analgesia after shoulder surgery. Single-injection LB nerve blocks were found to be superior in reducing pain levels and opioid consumption compared with other anesthetic modalities.

Efficacy, safety, and pharmacokinetics of CPL-01, an investigational long-acting ropivacaine, in bunionectomy: Results of a phase 2b study

CPL-01 (ropivacaine extended-release injection) is formulated to safely provide postoperative analgesia and reduce opioid use. Participants undergoing unilateral distal first metatarsal bunionectomy with osteotomy were randomized to receive either CPL-01 (200 mg in Cohort 1, 300 mg in Cohort 2), ropivacaine HCl (50 mg in Cohort 1, 75 mg in Cohort 2), or volume-matched placebo into the surgical site prior to closure. Participants remained in an inpatient setting for 72 h to assess efficacy (Numeric Rating Scale [NRS] scores for pain with activity adjusted for opioid usage, and rescue medication usage), safety and pharmacokinetics. Seventy-three participants were randomized and treated, and 71 participants completed the study. Participants who received 300 mg CPL-01 had a mean (SD) area under the curve from 0 to 72 h (AUC0-72) of the NRS score with activity of 356.9 (132.82), which was lower than placebo, indicating less pain. Participants who received CPL-01 300 mg also had numerically lower mean total opioid consumption. CPL-01 was safe and well-tolerated, with no evidence of increased AEs in one group versus another. Infiltration of CPL-01 had no impact on wound or bone healing. CPL-01 showed predictable and consistent extended-release pharmacokinetics, with no indication of "dose-dumping." Ropivacaine HCl delivered 94.3-99.7 % of its ropivacaine dose in the first 24 h; the 300 mg CPL-01 dose delivered 38.5 %. While this Phase 2b study was small, results demonstrated the safety, efficacy, and extended-release characteristics of this long-acting ropivacaine formulation in this surgical model, supporting further development of CPL-01 in Phase 3 clinical studies.

Efficacy of pectoralis nerve blocks I & II with liposomal bupivacaine in patients undergoing elective breast reduction procedures: A retrospective study

Background

The pectoral nerve (PECs) block I and II nerve blocks with liposomal bupivacaine (LB, Exparel) are used for postoperative analgesia in breast surgery, but evidence on efficacy for breast reduction is limited. We examined the effect of the PECS I and II blocks with LB on perioperative opioid use and pain scores compared to no block and blocks with plain local anesthetic (LA). We hypothesized that patients receiving a block with LB would require lower opioid amounts.

Methods

This retrospective cohort analysis included 120 patients undergoing breast reduction from 2011-2023. Patients received: no block, PECs block with plain LA, or PECs block with LB. Primary outcomes were intraoperative, Post-Anesthesia Care Unit (PACU), and outpatient opioid requirements. The secondary outcomes were PACU pain scores.

Results

Forty patients had no block, twenty-six received plain LA block, and fifty-four received LB block. For intraoperative opioids, LB block significantly lowered use compared to no block. PACU opioid use showed no differences between groups. For outpatient opioids, both LB and plain LA blocks significantly lowered use compared to no block. No significant pain score differences were found between groups.

Conclusions

Patients receiving the PECS block had decreased outpatient narcotic requirements compared to those patients who did not get the block. Patients receiving PECS block with LB had the further benefit of having decreased intraoperative narcotic requirements compared to the other groups. This highlights the potential benefit of performing the PECS block for patients undergoing breast reduction surgery.

Liposomal bupivacaine after arthroscopic rotator cuff repair moderately decreases early postoperative pain and demonstrates equivocal opioid consumption compared to traditional interscalene nerve blocks: A systematic review and meta-analysis of level 1 studies

BACKGROUND

Interscalene nerve blocks (ISNBs) reduce length of stay, postoperative pain, and opioid consumption following arthroscopic rotator cuff repair (ARCR). ISNBs with anesthetic agents like bupivacaine are associated with intense rebound pain, while liposomal bupivacaine (LB) can potentially extend pain relief up to 72 h and reduce opioid consumption. The purpose of this systematic review and meta-analysis is to compare the efficacy of LB versus traditional ISNB for postoperative pain management and opioid consumption following ARCR.

METHODS

A systematic review following PRISMA guidelines was performed from inception through March 2024. Randomized controlled trials comparing LB and traditional ISNB for postoperative pain management and opioid consumption following ARCR were included. The meta-analysis on each outcome measure was outlined in a forest plot detailing the standard mean difference (SMD) for continuous variables.

RESULTS

Data was extracted from 5 articles on 362 patients who underwent ARCR, 196 of whom received LB and 166 with a control non-LB ISNB. LB interventions had significantly lower pain scores than controls on postoperative day (POD) 1 and POD 2 (SMD -3.45, 95% CI [-5.20, -1.60]; P = 0.0003 and SMD -2.39, 95% CI [-4.01, -0.77]; P = 0.004, respectively). There was a significantly lower oral morphine equivalent dosage consumption in the LB cohort than controls on POD 0, POD 1, POD 2, and POD 3 (SMD -4.66; 95% CI, -7.95 to -1.36; p = 0.006; SMD -3.77; 95% CI, -5.69 to -1.85; p = 0.0001, SMD -3.34 95% CI [-5.13, -1.56]; p = 0.0002, and SMD -3.43; 95% CI, -5.74 to -1.12; p = 0.004, respectively).

DISCUSSION

LB moderately decreased pain scores 24-72 h postoperatively and reduced opioid consumption for up to 96 h following ARCR compared to a control ISNB cohort. However, the clinical difference in opioid usage may not translate to patient benefits or justify the increased cost.

LEVEL OF EVIDENCE

I.

Liposomal bupivacaine as one component of the postoperative management of limb amputations in cats: a retrospective study

OBJECTIVES

The objective of this study was to evaluate the impact of liposomal bupivacaine (LB) as part of an opioid-sparing multimodal analgesic protocol on postoperative pain control in cats undergoing limb amputation surgery compared with traditional pain management protocols more heavily reliant on injectable opioid and non-opioid analgesics.

METHODS

Medical records of 29 cats that underwent forelimb or hindlimb amputation were reviewed to evaluate postoperative systemic pain medications utilized, appetite and time to discharge as presumptive gauges of postoperative pain. Statistical analysis of the data included Wilcoxon's rank-sum test and Fisher's exact test.

RESULTS

Of the 29 cats, seven (24%) did not receive LB and 22 (76%) did. No statistically significant differences were found between the two groups in the outcome variables evaluated. The median time to eating was similar (6.0 h in the LB group vs 5.0 h in the non-LB group), the median time to discharge was shorter in the LB group (25.0 h vs 42.0 h in the non-LB group) and the median time to discontinuation of opioids in the LB treatment group was shorter than the non-LB group (18.0 h in LB group vs 22.0 h non-LB). A lower proportion of the LB group needed adjuvant systemic analgesics compared with the non-LB group (5% LB vs 29% non-LB).

CONCLUSIONS AND RELEVANCE

The addition of liposomal bupivacaine to an analgesic protocol after limb amputation in cats is associated with reduced opioid dosing, earlier return to eating and earlier hospital discharge. The use of LB may minimize the negative side effects associated with systemic opioid administration and therefore decrease patient morbidity. Future studies are needed to definitively compare LB efficacy and safety for postoperative pain control and traditional systemic analgesic medications.

Anterior Transversus Abdominis Plane Block for Lower Extremity Revascularization

INTRODUCTION

Regional anesthesia remains underutilized in vascular surgery; therefore, we retrospectively reviewed and compared the usage of perioperative opioids in patients undergoing lower extremity revascularization surgery, who received the anterior transversus abdominis plane (TAP) block along with local anesthesia at the incision site versus who did not receive any regional anesthesia.

METHODS

We conducted a retrospective review of 107 patients undergoing open or hybrid lower extremity revascularization under general anesthesia at a single institution between 2017 and 2022. Patients were divided into two groups. Regional block group (n = 41 [38%]) (femoral endarterectomy 27%; femoral endarterectomy + endovascular intervention 51%; infrainguinal bypass 22%) received both an intraoperative anterior TAP block and local anesthesia at the incision site; No regional block group (n = 66 [62%]) (femoral endarterectomy 29%; femoral endarterectomy + endovascular intervention 13%; infrainguinal bypass 58%) did not receive either regional or local anesthesia.

RESULTS

There were no significant differences in either the procedural metrics or intraprocedural complications between the two groups. The in-hospital stay was shorter in the Regional group, 1 (1, 3) versus the No regional group, 3 (2, 7), P < 0.001. The median intraoperative morphine milliequivalents use was 20 (15, 25) in the Regional block group and 25 (20, 35) in the No regional block group, P = 0.008. The median postoperative opioids use at 24h was 75 (60, 98) in the Regional block group and 113 (83, 151) in the No regional block group, P < 0.001; at 48h was 103 (70, 118) in the Regional block group and 148 (90, 210) in the No regional block group, P = 0.027; at 72h was 105 (70, 138) in the Regional block group and 196 (113, 263) in the No regional block group, P = 0.010.

CONCLUSIONS

Anterior TAP block combined with local anesthesia at the incision site seems to be a safe postoperative analgesia option for patients undergoing lower extremity revascularization surgery that could potentially help reducing both intra and postoperative opioids requirement.

Liposomal Bupivacaine Does Not Decrease Postoperative Pain in Patients with Intracapsular Femoral Neck Fracture Treated with Hemiarthroplasty: HEAT-A Randomized, Controlled Trial

BACKGROUND

Liposomal bupivacaine (LB) is a long-lasting local anesthetic agent that was developed for use in the surgical setting to help manage postoperative pain. The objective of this study was to evaluate the effect of LB on postoperative pain, function, and overall hospital course in patients with intracapsular hip fractures who were treated with hip hemiarthroplasty.

METHODS

This was a single-center, randomized prospective double-blinded study of 50 patients with an isolated intracapsular femoral neck fracture who were treated with hip hemiarthroplasty from 2018 to 2022. The study group consisted of 25 patients who were treated with intraoperative LB and bupivacaine hydrochloride injections, while the control group consisted of 25 patients who were treated with intraoperative bupivacaine hydrochloride injections only. Primary outcomes were a visual analog scale (VAS) score for pain, total morphine milligram equivalents (MME), delirium, and time to ambulation with physical therapy.

RESULTS

No significant differences between the study and control groups were found in any of the outcomes measured. Most notably, there were no differences in the average postoperative pain score (VAS, 2.26 versus 2.7; p = 0.34), total MME used postoperatively (11.73 versus 9.98 MME; p = 0.71), and postoperative day of discharge (4.00 versus 3.88 days; p = 0.82).

CONCLUSIONS

The results of our study suggest that use of LB is not associated with substantially improved postoperative pain or function or with a shorter hospital course following hip hemiarthroplasty for a femoral neck fracture. Given the higher cost of LB compared with standard postoperative pain modalities, it is worth questioning its use in the setting of geriatric hip fractures.

LEVEL OF EVIDENCE

Therapeutic Level I . See Instructions for Authors for a complete description of levels of evidence.

Postoperative pain scores and opioid use after standard bupivacaine vs. liposomal bupivacaine regional blocks for abdominal cancer surgery: A propensity score matched study

BACKGROUND

Fascial plane blocks (FPBs) are widely used for abdominal surgery with the assumption that liposomal bupivacaine (LB) is more effective than standard bupivacaine (SB).

METHODS

This was a single-institution retrospective cohort study of patients administered FPBs with LB or SB ​+ ​admixtures (dexamethasone/dexmedetomidine) for open abdominal cancer surgery. Propensity score matching generated a 2:1 (LB:SB) matched cohort. Opioid use (mg oral morphine equivalents, OME) and severe pain (≥3 pain scores ≥7 in a 24-h period) were compared.

RESULTS

Opioid use was >150 ​mg OME in 19.9 ​% (29/146) LB and 16.4 ​% (12/73) SB patients (p ​= ​0.586). Severe pain was experienced by 44 ​% (64/146) LB and 53 ​% (39/73) SB patients (p ​= ​0.198). On multivariable analysis, SB vs LB choice was not associated with high opioid volume >150 ​mg or severe pain.

CONCLUSIONS

FPBs with standard bupivacaine were not associated with higher 72-h opioid use or more severe pain compared to liposomal bupivacaine.

Gene therapy for chronic pain management

Despite significant advances in identifying molecular targets for chronic pain over the past two decades, many remain difficult to target with traditional methods. Gene therapies such as antisense oligonucleotides (ASOs), RNA interference (RNAi), CRISPR, and virus-based delivery systems have played crucial roles in discovering and validating new pain targets. While there has been a surge in gene therapy-based clinical trials, those focusing on pain as the primary outcome remain uncommon. This review examines various gene therapy strategies, including ASOs, small interfering RNA (siRNAs), optogenetics, chemogenetics, and CRISPR, and their delivery methods targeting primary sensory neurons and non-neuronal cells, including glia and chondrocytes. We also explore emerging gene therapy tools and highlight gene therapy's clinical potential in pain management, including trials targeting pain-related diseases. Advances in single-cell analysis of sensory neurons and non-neuronal cells, along with the development of new delivery tools, are poised to accelerate the application of gene therapy in pain medicine.

Evaluating the efficacy and safety of perianal injection of liposomal ropivacaine HR18034 for postoperative analgesia following hemorrhoidectomy: A multicenter, randomized, double-blind, controlled phase II clinical trial

STUDY OBJECTIVE

HR18034, composed of the ropivacaine encapsulated in multi-lamellar, concentric circular structure liposomes as the major component and a small amount of free ropivacaine, has performed well in animal experiments and phase I clinical trials. This trial was to investigate the efficacy, safety, pharmacokinetic profile and the minimum effective dose of HR18034 for postoperative analgesia after hemorrhoidectomy compared with ropivacaine.

DESIGN

A multicenter, randomized, double-blind trial.

SETTING

19 medical centers in China.

PATIENTS

85 patients undergoing hemorrhoidectomy between October 2022 to November 2022.

INTERVENTIONS

Patients were randomly divided into HR 18034 190 mg group, 285 mg group, 380 mg group and ropivacaine 75 mg group, receiving single local anesthetic perianal injection for postoperative analgesia.

MEASUREMENTS

The primary outcome was the area under the resting state NRS score -time curve within 72 h after injection. The second outcomes included the proportion of patients without pain, the proportion of patients not requiring rescue analgesia, cumulative morphine consumption for rescue analgesia, etc. Safety was evaluated by adverse events incidence and plasma ropivacaine concentrations were measured to explore the pharmacokinetic characteristics of HR18034.

MAIN RESULTS

The areas under the NRS score (at rest and moving states)-time curve were significantly lower in HR 18034 380 mg group than ropivacaine 75 mg at 24 h, 48 h, and 72 h after administration. However, this superiority was not observed in HR18034 190 mg group and 285 mg group. There was no difference in cumulative morphine consumption for rescue analgesia between HR 18034 groups and ropivacaine group.

CONCLUSIONS

HR 18034 380 mg showed superior analgesic efficacy and equivalent safety compared to ropivacaine 75 mg after hemorrhoidectomy, thus preliminarily determined as minimum effective dose.

A cutting-edge new framework for the pain management in children: nanotechnology

Pain is a subjective concept which is ever-present in the medical field. Health professionals are confronted with a variety of pain types and sources, as well as the challenge of managing a patient with acute or chronic suffering. An even bigger challenge is presented in the pediatric population, which often cannot quantify pain in a numerical scale like adults. Infants and small children especially show their discomfort through behavioral and physiological indicators, leaving the health provider with the task of rating the pain. Depending on the pathophysiology of it, pain can be classified as neuropathic or nociceptive, with the first being defined by an irregular signal processing in the nervous system and the second appearing in cases of direct tissue damage or prolonged contact with a certain stimulant. The approach is generally either pharmacological or non-pharmacological and it can vary from using NSAIDs, local anesthetics, opiates to physical and psychological routes. Unfortunately, some pathologies involve either intense or chronic pain that cannot be managed with traditional methods. Recent studies have involved nanoparticles with special characteristics such as small dimension and large surface area that can facilitate carrying treatments to tissues and even offer intrinsic analgesic properties. Pediatrics has benefited significantly from the application of nanotechnology, which has enabled the development of novel strategies for drug delivery, disease diagnosis, and tissue engineering. This narrative review aims to evaluate the role of nanotechnology in current pain therapy, with emphasis on pain in children.

Safety and Efficacy of Vocacapsaicin for Management of Postsurgical Pain: A Randomized Clinical Trial

BACKGROUND

Nonopioid management of postsurgical pain remains a major unmet need. Few studies have evaluated transient receptor potential vanilloid subfamily member 1 agonists for analgesia after surgery. This study examines intraoperative vocacapsaicin, a novel prodrug of the transient receptor potential vanilloid subfamily member 1 agonist capsaicin, in a validated model of postsurgical pain.

METHODS

This was a triple-blinded, randomized, placebo-controlled, dose-ranging trial in patients undergoing bunionectomy. Patients were randomized 1:1:1:1 to surgical site administration of 14 ml of placebo or one of three vocacapsaicin concentrations: 0.30, 0.15, or 0.05 mg/ml. The prespecified primary endpoint was the area-under-the-curve of the numerical rating scale pain score at rest through 96 h for the 0.30 mg/ml group. Prespecified ordered, secondary endpoints for the 0.30 mg/ml group included the percentage of patients who did not require opioids from 0 to 96 h, total opioid consumption through 96 h, and the area-under-the-curve of the numerical rating scale pain score for the first week.

RESULTS

The 147 patients were randomized. During the first 96 h, vocacapsaicin (0.30 mg/ml) reduced pain at rest by 33% versus placebo (primary endpoint, 95% CI [10%, 52%], effect size [Cohen's d] = 0.61, P = 0.005). Of patients receiving vocacapsaicin (0.30 mg/ml), 26% did not require postoperative opioids for analgesia (P = 0.025) versus 5% of patients receiving placebo. Vocacapsaicin (0.30 mg/ml) reduced opioid consumption over the first 96 h by 50% versus placebo (95% CI [26%, 67%], effect size = 0.76, P = 0.002). Vocacapsaicin (0.30 mg/ml) reduced pain over the first week by 37% versus placebo (95% CI [12%, 57%], effect size = 0.62, P = 0.004). The treatment effect persisted for at least 2 weeks. All study endpoints showed an administered concentration-versus-response relationship. Vocacapsaicin was well tolerated with no differences between groups in any safety parameter.

CONCLUSIONS

A single, local administration of vocacapsaicin during surgery reduced pain and opioid consumption for at least 96 h after surgery compared to control.

EDITOR’S PERSPECTIVE

Extended Release of Bupivacaine from Temperature-Responsive PNDJ Hydrogels Improves Postoperative Weight-Bearing in Rabbits Following Knee Surgery

Effective treatment of postoperative pain lasting for multiple days without opioids is an important clinical need. We previously reported analgesia lasting up to 96 h in a porcine soft tissue model of postoperative pain using SBG004, an extended-release formulation of bupivacaine based on the temperature-responsive polymer poly(N-isopropylacrylamide-co-dimethylbutyrolactone acrylamide-co-Jeffamine M-1000 acrylamide) [PNDJ]. Orthopaedic surgical sites such as the knee can involve complex sensory innervation which presents a distinct challenge to local anesthetic delivery. The purpose of this work was to evaluate the pharmacokinetics and efficacy of SBG004 in an orthopaedic surgical model in comparison to currently available local anesthetics. Pharmacokinetics following periarticular (PA) or intraarticular (IA) injection of SBG004 were compared against liposomal bupivacaine (Lip-Bupi) PA in New Zealand White rabbits (all doses 14.5 mg/kg). Analgesic efficacy of SBG004 (IA, PA, or IA + PA), three active comparators, and saline was evaluated following knee surgery in New Zealand White rabbits. Analgesia was assessed via weight-bearing on the operated limb during spontaneous large steps in video recordings. Systemic bupivacaine exposure lasted at least 7 days for SBG004 PA, 4 days for SBG004 IA, and 2 days for Lip-Bupi PA. In the analgesia study, weight-bearing in all active groups except SBG004 IA was more frequent versus saline through 8 h postoperatively (p < 0.05). Only SBG004 IA + PA resulted in a higher proportion of weight-bearing rabbits at 24 h versus saline (6/7 versus 2/10, p = 0.015). Analysis of pooled data from 24-72 h showed significantly greater frequency of weight-bearing in rabbits receiving SBG004 IA + PA (71%) versus saline (37%), ropivacaine cocktail (41%), and Lip-Bupi PA (36%). The results indicate that the release profile from SBG004 PA or IA coincides reasonably with the time course of postoperative pain, and SBG004 may produce longer duration of analgesia than local anesthetics currently used in knee surgery, including during the period of 24-72 h recognized as a target for extended-release local anesthetics.

Management of Hemorrhoids and Anal Fissures

Hemorrhoids and anal fissures are two of the most common benign anorectal diseases. Despite their high prevalence, diagnostic accuracy of benign anorectal disease is suboptimal at 70% for surgeons, especially for hemorrhoidal diseases. Once the diagnosis is correctly made, numerous medical and surgical treatment options are available, each with different rates of success and complications. In this article, the authors review each step of patient management, with emphasis on evidence-based treatment options for hemorrhoids and anal fissures. The article discusses the pathophysiology, diagnosis, medical management, and procedures for hemorrhoids followed by a detailed overview on the management of anal fissures.

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.

The effect of bupivacaine on analgesia and safety in patients undergoing hemorrhoidectomy: a meta-analysis

Aim: There is no meta-analysis reporting the analgesic effect and safety of bupivacaine in patients undergoing hemorrhoidectomy. This meta-analysis provides quantitative evidence of the effect of bupivacaine in hemorrhoidectomy. Methods: Studies were searched from PubMed, Embase, the Cochrane Library, and the Web of Science. Standardized mean difference (SMD), weighted mean difference (WMD), and odds ratios (ORs) with 95% confidence interval (CI) were used as effect indicators. Heterogeneity was assessed using the I 2 index, and sensitivity analysis was conducted to determine the effect of the single study on the pooled results. Results: A total of 18 studies were included in this meta-analysis. The pain level at 48 h was lower in the bupivacaine-combined other drug group than in the other drug group (WMD = -0.65, 95% CI: 1.18 to -0.11, and I2 = 37.50%). Compared to the bupivacaine group, the odds of pruritus (OR = 12.11, 95% CI: 1.49-98.59, and I2 = 0%) and urinary retention (OR = 4.45, 95% CI: 1.12-17.70, and I2 = 0%) were higher, and the pain level at 6 h (WMD = -2.13, 95% CI: 3.22 to -1.04, and I2 = 64.30%), at 12 h (WMD = -1.55, 95% CI: 2.19 to -0.90, and I2 = 56.10%), and at 24 h (SMD = -1.15, 95% CI: 1.89 to -0.42, and I2 = 82.5%) were lower in the bupivacaine-combined other drug group. Conclusion: Bupivacaine-combined other drugs had a good analgesic effect after hemorrhoidectomy, but the adverse reactions should be considered.

Randomized Controlled Trial Comparing Liposomal to Plain Bupivacaine in the Transversus Abdominis Plane for DIEP Flap Breast Reconstruction

BACKGROUND

Pain control after autologous breast reconstruction is important for patient satisfaction and early recovery. Transversus abdominis plane (TAP) blocks are commonly used as part of an enhanced recovery after surgery (ERAS) pathway for breast reconstruction. It is uncertain whether liposomal bupivacaine used in TAP blocks offers additional advantages. This study aimed to compare the efficacy of liposomal bupivacaine versus plain bupivacaine for patients undergoing deep inferior epigastric perforator flap reconstruction.

METHODS

This double-blinded randomized controlled trial studied patients undergoing abdominally based autologous breast reconstruction between June of 2019 and August of 2020. Subjects were randomly assigned liposomal or plain bupivacaine, performed using ultrasound-guided TAP block technique. All patients were managed according to an ERAS protocol. Primary outcomes were postoperative narcotic analgesia required, measured in oral morphine equivalents from postoperative days 1 to 7. Secondary outcomes included numeric pain scale score on postoperative days 1 to 7, nonnarcotic pain medication use, time to first narcotic use, return of bowel function, and length of stay.

RESULTS

Sixty patients were enrolled: 30 received liposomal bupivacaine and 30 received plain bupivacaine. There were no significant differences in demographics, daily oral morphine equivalent narcotic use, nonnarcotic pain medication use, time to narcotic use, numeric pain scale score, time to bowel function, or length of stay.

CONCLUSION

Liposomal bupivacaine does not confer advantages over plain bupivacaine when used in TAP blocks for abdominally based microvascular breast reconstruction in patients under ERAS protocols and multimodal approaches for pain control.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, I.

Liposomal bupivacaine interscalene blocks demonstrate a greater proportion of total shoulder arthroplasty patients with clinically tolerable pain: a retrospective quality improvement study of 491 patients

OBJECTIVE

To evaluate the effects of liposomal bupivacaine use for interscalene blocks on postoperative analgesia in total shoulder arthroplasty patients.

METHODS

De-identified total or reverse total shoulder arthroplasty patients between 2018 and 2021 were analyzed. Patients were grouped into single shot interscalene block with liposomal bupivacaine (LB) with plain bupivacaine, other block (OB) with other local anesthetics (mepivacaine, ropivacaine, or plain bupivacaine), or no block (NB). The primary outcome was the proportion of patients with clinically tolerable pain scores (mean VAS ≤4) from 0 to 24 ​h in each group. Secondary outcomes included averaged visual analog pain scores (VAS) and opioid consumption measured in morphine milligram equivalents (MMEs) from 0 to 24 ​h. We also analyzed the proportion of patients with clinically tolerable pain, mean VAS, and opioid consumption from 0 to 72 ​h in those patients with at least a 3-day hospital length of stay.

RESULTS

A total of 491 de-identified total shoulder arthroplasty patients, 285 liposomal bupivacaine group (LB), 178 other block group (OB), and 28 no block group (NB), were analyzed. The primary outcome showed a statistically significant different proportion of patients with clinically tolerable pain from 0 to 24 ​h in the LB group (69 ​%) vs. OB group (39 ​%) vs. NB group (11 ​%) (<0.001). Secondary outcomes included statistically significant differences in VAS (LB median ​= ​3.35, OB median ​= ​4.38, NB median ​= ​5.25 (p ​< ​0.001, <0.001)) and total MME opioid consumption (LB median ​= ​40, OB median ​= ​60, NB median ​= ​88 (p ​< ​0.001, 0.001)) between groups from 0 to 24 ​h. For patients who had hospital stays of at least 3 days, a significant association was found with having achieved clinically tolerable pain 0-72 ​h and the LB group (51 ​%) vs. OB group (21 ​%) vs. NB group (11 ​%) (P ​= ​0.006). However, there was no statistical difference in mean VAS or opioid consumption between these groups.

CONCLUSION

A greater proportion of total shoulder arthroplasty patients that received liposomal bupivacaine in interscalene block have clinically tolerable pain scores from 0 to 24 ​h, lower VAS, and lower MME consumption in patients following total shoulder arthroplasty.

LEVEL OF EVIDENCE

Level III - Clinical Study.

Liposomal bupivacaine versus conventional anesthetic or placebo for hemorrhoidectomy: a systematic review and meta-analysis

BACKGROUND

Liposome bupivacaine (LB) is a long-acting anesthetic to enhance postoperative analgesia. Studies evaluating the efficacy of the LB against an active comparator (bupivacaine or placebo) on acute postoperative pain control in hemorrhoidectomy procedures are few and heterogeneous. Therefore, we performed a systematic review and meta-analysis comparing LB's analgesic efficacy and side effects to conventional/placebo anesthetic in hemorrhoidectomy patients.

METHODS

We performed a systematic review and meta-analysis of randomised controlled trials investigating the use of LB after haemorrhoidectomy. We searched the literature published from the time of inception of the datasets to August 19, 2022. The electronic databases included English publications in Ovid MEDLINE In-Process & Other Non-Indexed Citations, Ovid MEDLINE, Ovid EMBASE, and Scopus.

RESULTS

A total of 338 patients who underwent a hemorrhoidectomy procedure enrolled in three randomized clinical trials were included. The overall mean age was 45.84 years (SD ± 11.43), and there was a male predominance (53.55% male). In total 194 patients (52.2%) received LB and 144 (47.8%) received either bupivacaine or placebo. Pain scores at 72 h in the LB (199, 266, and 300 mg) were significantly lower than in the bupivacaine HCl group (p = 0.002). Compared to the bupivacaine/placebo group, the time to first use of opioids in the LB group was significantly longer at LB 199 mg (11 h vs. 9 h), LB 266 mg (19 h vs. 9 h), and LB 300 mg (19 h vs. 8 h) (p < 0.05). Moreover, compared to the bupivacaine/epinephrine group, it was significantly lower in the LB 266 mg group (3.7 vs. 10.2 mg) and at LB 300 mg (13 vs. 33 mg) (p < 0.05). Finally, regarding adverse effects, the conventional anesthetic/placebo group reported more pain in bowel movement than LB groups (OR 2.60, 95% CI 1.31-5.16).

CONCLUSIONS

Comparing LB to conventional anesthetic/placebo anesthetic for hemorrhoidectomy, we found a statistically significant reduction in pain through 72 h, decreased opioid requirements, and delayed time to first opioid use. Moreover, the conventional anesthetic/placebo group reported more pain in bowel movement than LB groups.

Liposomal and Nonliposomal Bupivacaine for Mohs Surgery: A Systematic Review

BACKGROUND

Lidocaine is the most commonly used local anesthetic for Mohs micrographic surgery (MMS), but given its limited half-life, postoperative pain remains a significant concern for patients. Bupivacaine is used in various surgical subspecialty procedures and has demonstrated improved pain control compared with lidocaine. However, its role in MMS is insufficiently explored.

OBJECTIVE

To systematically review the current literature for reports on use of bupivacaine, traditional nonliposomal and newer liposomal formulations, for MMS.

METHODS

A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines. The MEDLINE, PubMed, and EMBASE databases were queried for articles presenting original data on the use of bupivacaine for MMS.

RESULTS

Of 483 potentially relevant articles, 3 studies met final inclusion criteria, capturing a total of 253 patients involved in primary investigations comparing bupivacaine to traditional local anesthesia for MMS. Bupivacaine was well-tolerated and associated with comparable or modestly reduced intraoperative and postoperative pain and opioid use.

CONCLUSION

Bupivacaine may have a role in prolonging intraoperative anesthesia, reducing acute postoperative pain, and reducing postoperative opioid use after MMS. However, large, prospective studies are needed to solidify the generalizability and clinical utility of these findings.

Application of Advanced Technologies-Nanotechnology, Genomics Technology, and 3D Printing Technology-In Precision Anesthesia: A Comprehensive Narrative Review

There has been increasing interest and rapid developments in precision medicine, which is a new medical concept and model based on individualized medicine with the joint application of genomics, bioinformatics engineering, and big data science. By applying numerous emerging medical frontier technologies, precision medicine could allow individualized and precise treatment for specific diseases and patients. This article reviews the application and progress of advanced technologies in the anesthesiology field, in which nanotechnology and genomics can provide more personalized anesthesia protocols, while 3D printing can yield more patient-friendly anesthesia supplies and technical training materials to improve the accuracy and efficiency of decision-making in anesthesiology. The objective of this manuscript is to analyze the recent scientific evidence on the application of nanotechnology in anesthesiology. It specifically focuses on nanomedicine, precision medicine, and clinical anesthesia. In addition, it also includes genomics and 3D printing. By studying the current research and advancements in these advanced technologies, this review aims to provide a deeper understanding of the potential impact of these advanced technologies on improving anesthesia techniques, personalized pain management, and advancing precision medicine in the field of anesthesia.

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.

Bilateral transversus abdominis plane and rectus sheath blocks with liposomal bupivacaine for patients undergoing robotic prostatectomy

As robotic prostatectomy surgery becomes more prevalent, it is important to identify any regional techniques to optimize patient's recovery. We evaluated the effectiveness of bilateral transversus abdominis plane (TAP) and rectus sheath (RS) blocks with liposomal bupivacaine. We hypothesized that these blocks would reduce perioperative opioid use and pain scores. A retrospective cohort of patients from May 2018 and May 2021 at a single large VA hospital were studied. We compared those not receiving a nerve block against those receiving the TAP and RS as part of an Enhanced Recovery After Surgery (ERAS) pathway starting in May 2019. The primary outcome was post-operative opioid use. Secondary outcomes were post-operative pain scores and hospital length of stay. One hundred and thirty-four patients were included in the final analysis. Eighty-one patients did not receive a block and fifty-three patients did receive a block. No difference existed between the groups in regard to median oral morphine equivalents (mg) used in PACU or any post-operative day. No difference existed in median opioid usage (mg) or pain scores between the two groups on any post-operative day. There was no difference in temporal association of median pain scores or narcotic usage between the two groups. Bilateral TAP and RS with liposomal bupivacaine did not significantly decrease post-operative opioid use, improve pain scores, or decrease hospital length of stay for patients undergoing robotic prostatectomy. Further studies need to be done to evaluate the effect of these blocks with liposomal bupivacaine.

Characterization of exparel bupivacaine multivesicular liposomes

Exparel is a bupivacaine multivesicular liposomes (MVLs) formulation developed based on the DepoFoam technology. The complex composition and the unique structure of MVLs pose challenges to the development and assessment of generic versions. In the present work, we developed a panel of analytical methods to characterize Exparel with respect to particle size, drug and lipid content, residual solvents, and pH. In addition, an accelerated in vitro drug release assay was developed using a rotator-facilitated, sample-and-separate experimental setup. The proposed method could achieve over 80% of bupivacaine release within 24 h, which could potentially be used for formulation comparison and quality control purposes. The batch-to-batch variability of Exparel was examined by the established analytical methods. Four different batches of Exparel showed good batch-to-batch consistency in drug content, particle size, pH, and in vitro drug release kinetics. However, slight variation in lipid contents were observed.

The use of liposomal bupivacaine in fracture surgery: a review

Historically, opioids have played a major role in the treatment of postoperative pain in orthopedic surgery. A multitude of adverse events have been associated with opioid use and alternative approaches to pain relief are being investigated, with particular focus on multimodal pain management regimens. Liposomal bupivacaine (EXPAREL) is a component of some multimodal regimens. This formulation of bupivacaine encapsulates the local anesthetic into a multivesicular liposome to theoretically deliver a consistent amount of drug for up to 72 hours. Although the use of liposomal bupivacaine has been studied in many areas of orthopedics, there is little evidence evaluating its use in patients with fractures. This systematic review of the available data identified a total of eight studies evaluating the use of liposomal bupivacaine in patients with fractures. Overall, these studies demonstrated mixed results. Three studies found no difference in postoperative pain scores on postoperative days 1-4, while two studies found significantly lower pain scores on the day of surgery. Three of the studies evaluated the quantity of narcotic consumption postoperatively and failed to find a significant difference between control groups and groups treated with liposomal bupivacaine. Further, significant variability in comparison groups and study designs made interpretation of the available data difficult. Given this lack of clear evidence, there is a need for prospective, randomized clinical trials focused on fully evaluating the use of liposomal bupivacaine in fracture patients. At present, clinicians should maintain a healthy skepticism and rely on their own interpretation of the available data before widely implementing the use of liposomal bupivacaine.

The effect of liposomal bupivacaine for surgical wound infiltration: A meta‐analysis of randomised controlled trials

Liposomal bupivacaine (LB) has consistently been considered a potential analgesic for surgical wound infiltration. However, the evidence of its analgesic effectiveness remains unclear. In this meta-analysis, we attempted to identify the potential clinical role of LB wound infiltration in different surgical procedures. Randomised controlled trials (RCTs) comparing LB with non-liposomal local anaesthetics and placebos were retrieved from six electronic databases. The primary outcome was cumulative morphine equivalent consumption within 24, 48, and 72 hours after surgery. Approximately 2659 patients from 22 studies were included in the meta-analysis. Compared to the control, LB-wound infiltration did not reduce the postoperative morphine consumption at 24 hours (weighted mean difference [WMD], -0.60 mg; 97.5% confidence interval [CI], -2.78 to 1.59 mg; P = 0.54), 48 hours (WMD, -1.00 mg; 97.5% CI, -3.23 to 1.24; P = 0.32) or 72 hours (WMD, 0.50 mg; 97.5% CI, -0.67 to 1.67; P = 0.33). Similarly, secondary outcome analysis did not reveal any additional benefits of LB in any other pain-related outcomes. LB was not associated with any adverse effects. Overall, LB does not appear to improve the postoperative analgesic, rehabilitation, or safety outcomes. Current evidence does not support the routine use of LB for wound infiltration following surgical procedures.

Evaluation of liposomal bupivacaine infiltration at reconstructive skin graft donor sites in adolescent and young adult burn patients: A retrospective analysis

BACKGROUND

Postoperative pain at skin graft donor sites is frequently undertreated in burn patients, which can impair reconstructive outcomes and result in harmful psychological consequences. We find a critical need to explore and promote non-opioid, multimodal analgesics. Donor site infiltration of the local anesthetic liposomal bupivacaine in adolescent and young adult burn patients has not been previously investigated. Therefore, the goal of this study was to evaluate intraoperative liposomal bupivacaine infiltration for postoperative donor site pain control in adolescent and young adult burn patients undergoing reconstructive skin graft procedures.

METHODS

This retrospective analysis included patients aged 14-25 years, who underwent at least two reconstructive skin graft procedures, one that received donor site infiltration of the standard treatment (bupivacaine hydrochloride) and one that received donor site infiltration of liposomal bupivacaine. The final sample included 30 patients with a total of 44 liposomal bupivacaine cases and 53 standard treatment cases analyzed.

RESULTS

In the authors' five-year experience, the use of liposomal bupivacaine compared to standard treatment was associated with statistically significant decreases in 0-4 h postoperative pain scores (mean 1.4/10 versus 2.3/10, p = 0.04) and 0-24 h postoperative pain scores (mean 1.7/10 versus 2.4/10, p = 0.02). Neither analgesic was associated with adverse events. Differences in length of stay and inpatient postoperative opioid usage were not regarded as significant.

CONCLUSION

In this retrospective analysis, the authors report the first results that suggest intraoperative liposomal bupivacaine donor site infiltration may be associated with statistically improved patient outcomes in adolescent and young adult burn patients. However, the reported differences are most likely not clinically significant, establishing the necessity for further evaluation of using liposomal bupivacaine in this unique patient population.

Ultrasound-Triggered on Demand Lidocaine Release Relieves Postoperative Pain

Safe and non-invasive on-demand relief is a crucial and effective treatment for postoperative pain because it considers variable timing and intensity of anesthetics. Ultrasound modulation is a promising technique for this treatment because it allows convenient timed and non-invasive controlled drug release. Here, we created an ultrasound-triggered lidocaine (Lido) release platform using an amino acid hydrogel functioning as three-dimensional (3D) scaffold material (Lido-PPIX@ER hydrogel). It allows control of the timing, intensity and duration of lidocaine (Lido) to relieve postoperative pain. The hydrogel releases Lido due to the elevated reactive oxygen species (ROS) levels generated by PPIX under ultrasound triggering. The Lido-PPIX@ER hydrogel under individualized ultrasound triggering released lidocaine and provided effective analgesia for more than 72 h. The withdrawal threshold was higher than that in the control group at all time points measured. The hydrogel showed repeatable and adjustable ultrasound-triggered nerve blocks in vivo, the duration of which depended on the extent and intensity of insonation. On histopathology, no systemic effect or tissue reaction was observed in the ultrasound-triggered Lido-PPIX@ER hydrogel-treated group. The Lido-PPIX@ER hydrogel with individualized (highly variable) ultrasound triggering is a convenient and effective method that offers timed and spatiotemporally controlled Lido release to manage postoperative pain. This article presents the delivery system for a new effective strategy to reduce pain, remotely control pain, and offer timed and spatiotemporally controlled release of Lido to manage postoperative pain.

Recent advances in pain management based on nanoparticle technologies

BACKGROUND

Pain is a vital sense that indicates the risk of injury at a particular body part. Successful control of pain is the principal aspect in medical treatment. In recent years, the advances of nanotechnology in pain management have been remarkable. In this review, we focus on literature and published data that reveal various applications of nanotechnology in acute and chronic pain management.

METHODS

The presented content is based on information collected through pain management publications (227 articles up to April 2021) provided by Web of Science, PubMed, Scopus and Google Scholar services.

RESULTS

A comprehensive study of the articles revealed that nanotechnology-based drug delivery has provided acceptable results in pain control, limiting the side effects and increasing the efficacy of analgesic drugs. Besides the ability of nanotechnology to deliver drugs, sophisticated nanosystems have been designed to enhance imaging and diagnostics, which help in rapid diagnosis of diseases and have a significant impact on controlling pain. Furthermore, with the development of various tools, nanotechnology can accurately measure pain and use these measurements to display the efficiency of different interventions.

CONCLUSIONS

Nanotechnology has started a new era in the pain management and many promising results have been achieved in this regard. Nevertheless, there is still no substantial and adequate act of nanotechnology in this field. Therefore, efforts should be directed to broad investigations.

Strategies to Reduce Post-Hemorrhoidectomy Pain: A Systematic Review

Background and Objectives: Excisional hemorrhoidectomy is considered as a mainstay operation for high-grade hemorrhoids and complicated hemorrhoids. However, postoperative pain remains a challenging problem after hemorrhoidectomy. This systematic review aims to identify pharmacological and non-pharmacological interventions for reducing post-hemorrhoidectomy pain. Materials and Methods: The databases of Ovid MEDLINE, PubMed and EMBASE were systematically searched for randomized controlled trails (published in English language with full-text from 1981 to 30 September 2021) to include comparative studies examining post-hemorrhoidectomy pain as their primary outcomes between an intervention and another intervention (or a sham or placebo). Results: Some 157 studies were included in this review with additional information from 15 meta-analyses. Fundamentally, strategies to reduce post-hemorrhoidectomy pain were categorized into four groups: anesthetic methods, surgical techniques, intraoperative adjuncts, and postoperative interventions. In brief, local anesthesia-alone or combined with intravenous sedation was the most effective anesthetic method for excisional hemorrhoidectomy. Regarding surgical techniques, closed (Ferguson) hemorrhoidectomy performed with a vascular sealing device or an ultrasonic scalpel was recommended. Lateral internal anal sphincterotomy may be performed as a surgical adjunct to reduce post-hemorrhoidectomy pain, although it increased risks of anal incontinence. Chemical sphincterotomy (botulinum toxin, topical calcium channel blockers, and topical glyceryl trinitrate) was also efficacious in reducing postoperative pain. So were other topical agents such as anesthetic cream, 10% metronidazole ointment, and 10% sucralfate ointment. Postoperative administration of oral metronidazole, flavonoids, and laxatives was associated with a significant reduction in post-hemorrhoidectomy pain. Conclusions: This systematic review comprehensively covers evidence-based strategies to reduce pain after excisional hemorrhoidectomy. Areas for future research on this topic are also addressed at the end of this article.

Efficacy of Liposomal Bupivacaine for Sternotomy Pain After Cardiac Surgery: A Retrospective Analysis

BACKGROUND

Multimodal analgesia is a cornerstone of postoperative pain management. Different formulations of local anesthetics are available. Data to support these treatment options are limited.

OBJECTIVE

To determine the efficacy of liposomal bupivacaine compared with bupivacaine or ropivacaine in patients undergoing sternotomy for coronary artery bypass graft (CABG) and/or valve surgery.

METHODS

Single-center, retrospective, observational study at a community teaching hospital. Patients included were 18 years of age or older undergoing CABG and/or valve surgery via median sternotomy and received either liposomal bupivacaine or an active comparator. The primary outcome was opioid utilization in morphine milligram equivalent (MME) from 0 to 72 hours.

RESULTS

A total of 376 patients were included, 223 in the liposomal bupivacaine arm and 153 in the active comparator arm. There was no difference in the MME use from 0 to 72 hours among patients in the liposomal bupivacaine group compared with the comparator group (114.2 mg [75.55] vs 107.6 mg [68.4], P = 0.38). After Bonferroni correction, there was no difference in pain scores at individual time points. At 24- and 48-hour post-op, pain scores were higher with liposomal bupivacaine at 4.4 (2.7) vs 3.5 (2.8) (P = 0.01) and 3.1 (2.9) vs 2.4 (2.6) (P = 0.02).

CONCLUSION AND RELEVANCE

Based on these findings and previous studies, liposomal bupivacaine should not be routinely used for CABG and/or valve surgery through a median sternotomy given lack of superiority. This helps inform surgical practice to the role of anesthetics as part of the multimodal analgesia regimen.

Intercostal liposomal bupivacaine injection for rib fractures: A prospective randomized controlled trial

BACKGROUND

Blunt chest wall injury accounts for 15% of trauma admissions. Previous studies have shown that the number of rib fractures predicts inpatient opioid requirements, raising concerns for pharmacologic consequences, including hypotension, delirium, and opioid dependence. We hypothesized that intercostal injection of liposomal bupivacaine would reduce analgesia needs and improve spirometry metrics in trauma patients with rib fractures.

METHODS

A prospective, double-blinded, randomized placebo-control study was conducted at a Level I trauma center as a Food and Drug Administration investigational new drug study. Enrollment criteria included patients 18 years or older admitted to the intensive care unit with blunt chest wall trauma who could not achieve greater than 50% goal inspiratory capacity. Patients were randomized to liposomal bupivacaine or saline injections in up to six intercostal spaces. Primary outcome was to examine pain scores and breakthrough pain medications for 96-hour duration. The secondary endpoint was to evaluate the effects of analgesia on pulmonary physiology.

RESULTS

One hundred patients were enrolled, 50 per cohort, with similar demographics (Injury Severity Score, 17.9 bupivacaine 17.6 control) and comorbidities. Enrolled patients had a mean age of 60.5 years, and 47% were female. Rib fracture number, distribution, and targets for injection were similar between groups. While both groups displayed a decrease in opioid use over time, there was no change in mean daily pain scores. The bupivacaine group achieved higher incentive spirometry volumes over Days 1 and 2 (1095 mL, 1063 mL bupivacaine vs. 900 mL, 866 mL control). Hospital and intensive care unit lengths of stay were similar and there were no differences in postinjection pneumonia, use of epidural catheters or adverse events bet ween groups.

CONCLUSION

While intercostal liposomal bupivacaine injection is a safe method for rib fracture-related analgesia, it was not effective in reducing pain scores, opioid requirements, or hospital length of stay. Bupivacaine injection transiently improved incentive spirometry volumes, but without a reduction in the development of pneumonia.

LEVEL OF EVIDENCE

Therapeutic/care management, Level II.

Efficacy of Liposomal Bupivacaine versus Ropivacaine in Adductor Canal Block for Total Knee Arthroplasty

Adductor canal block (ACB) is advantageous for postoperative analgesia in total knee arthroplasty (TKA) because it results in minimal motor block. Liposomal bupivacaine (LB) is Food and Drug Administration-approved extended-release formulation of bupivacaine for interscalene peripheral nerve blocks. Its use is increasing in the TKA setting, mainly as a local infiltration agent. We compared the efficacy of ACB using LB versus ropivacaine in TKA. Two cohorts of patients were retrospectively analyzed at a single institution receiving ropivacaine and LB ACB for TKA. Duration of LB ACB, time to first opioid use postrecovery room, amount of opioid use postrecovery room, length of stay (LOS), and average and highest pain scores were collected. A total of 91 and 142 TKA patients received ropivacaine and LB for ACB, respectively. At 8 hours postrecovery room, more patients in the LB group required no opioids compared with the ropivacaine group (p = 0.026). Mean opioid consumption was lower in the LB group than in the ropivacaine group at 8 and 24 hours postrecovery room, although statistical significance was only observed at 8 hours (p = 0.022). The highest pain score for patients in the two groups was not statistically different. The average pain score for patients with a 2-day LOS was higher in the LB group, but average pain scores were similar for patients with 1- and 3-day LOS. Median LOS for the LB and ropivacaine groups was 1 and 2 days, respectively (p < 0.0001). Significantly lower opioid use at 8 hours postrecovery room was seen in the LB group compared with the ropivacaine group. There was no difference in opioid use at 24 and 48 hours. There was also no advantage with LB ACB in decreasing pain scores. However, the LB ACB group demonstrated a significantly shorter LOS compared with the ropivacaine ACB group.

Transversus abdominis plane block with liposomal bupivacaine versus continuous epidural analgesia for major abdominal surgery: The EXPLANE randomized trial

OBJECTIVE

Compare transversus abdominis plane (TAP) blocks with liposomal bupivacaine were to epidural analgesia for pain at rest and opioid consumption in patients recovering from abdominal surgery.

BACKGROUND

ERAS pathways suggest TAP blocks in preference to epidural analgesia for abdominal surgery. However, the relative efficacies of TAP blocks and epidural analgesia remains unknown.

METHODS

Patients having major abdominal surgery were enrolled at six sites and randomly assigned 1:1 to thoracic epidural analgesia or bilateral/4-quadrant TAP blocks with liposomal bupivacaine. Intravenous opioids were used as needed. Non-inferiority margins were a priori set at 1 point on an 11-point pain numeric rating scale for pain at rest and at a 25% increase in postoperative opioid consumption.

RESULTS

Enrollment was stopped per protocol at 3rd interim analysis after crossing an a priori futility boundary. 498 patients were analyzed (255 had TAP blocks and 243 had epidurals). Pain scores at rest in patients assigned to TAP blocks were significantly non-inferior to those given epidurals, with an estimated difference of 0.09 points (CI: -0.12, 0.30; noninferiority P < 0.001). Opioid consumption during the initial 3 postoperative days in TAP patients was not non-inferior to epidurals, with an estimated ratio of geometric means of 1.37 (CI: 1.05, 1.79; non-inferiority P = 0.754). However, the absolute difference was only 21 mg morphine equivalents over the 3 days. Patients with epidurals were more likely to experience mean arterial pressures <65 mmHg than those given TAP blocks: 48% versus 31%, P = 0.006.

CONCLUSION

Pain scores at rest during the initial three days after major abdominal surgery were similar. Patients assigned to TAP blocks required more opioid then epidural patients but had less hypotension. Clinicians should reconsider epidural analgesia in patients at risk from hypotension.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02996227.

New peripheral nerve blocks and local anesthetics

PURPOSE OF REVIEW

To describe current developed regional blocks, their indications and clinical use. Furthermore, describe new local anesthetics recently introduced and the new agents in pipeline.

RECENT FINDINGS

There are multiple new blocks recently developed with the introduction of ultrasound to regional anesthesia and studies demonstrate effect in different surgical procedures. However, majority of the studies do not compare with gold standard and are relatively small to change clinical practice. Some of these blocks are: erector spinae plane block, infiltration between the popliteal artery and capsule of the posterior knee, pectoral nerve blocks, quadratus lumborum and transversus abdominis plane block. New local anesthetics and adjuvants have been developed in recent years. However, the studies with even with the oldest one introduced Exparel is currently questioned, large future studies are needed to determine efficacy and safety profile and compared with conventional local anesthetics.

SUMMARY

New regional block techniques and new local anesthetics have been introduced recently. However, the efficacy/safety and comparison to conventional techniques and local anesthetics are still needed. Future studies must focus on prolonging analgesia with least invasive regional technique and compare new local anesthetics with current ones.

Anesthesia in Total Shoulder Arthroplasty: A Systematic Review and Meta-Analysis

»

For shoulder arthroplasty, regional anesthesia is safer when compared with general anesthesia. There is insufficient evidence to demonstrate the superiority of regional anesthesia with respect to pulmonary complications and hospital length of stay.

»

Infiltration of the shoulder with local anesthetics offers no additional benefits compared with single-shot or continuous brachial plexus blocks for shoulder arthroplasty.

»

There is high-quality evidence (Level I) demonstrating lower pain scores and lower perioperative opioid requirements after a continuous peripheral nerve block compared with a single-shot nerve block. However, catheter dislodgment and logistical issues with catheter insertion are impediments to the widespread usage of a continuous nerve block with an indwelling catheter.

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Liposomal bupivacaine is comparable with non-liposomal local anesthetic agents with respect to pain relief, the opioid-sparing effect, and adverse effects in the first 48 hours after total shoulder arthroplasty.

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Perioperative dexamethasone administration improves postoperative pain control, decreases perioperative opioid requirements, and reduces postoperative nausea.

Preoperative pudendal block with liposomal and plain bupivacaine reduces pain associated with posterior colporrhaphy: a double-blinded, randomized controlled trial

BACKGROUND

Pelvic reconstructive surgery may cause significant postoperative pain, especially with posterior colporrhaphy, contributing to a longer hospital stay and increased pain medication utilization. Regional blocks are being increasingly utilized in gynecologic surgery to improve postoperative pain and decrease opioid usage, yet preoperative pudendal blocks have not been used routinely during posterior colporrhaphy.

OBJECTIVE

This study aimed to compare the effect of preoperative regional pudendal nerve block using a combination of 1.3% liposomal and 0.25% plain bupivacaine vs 0.25% plain bupivacaine alone on vaginal pain after posterior colporrhaphy on postoperative days 1, 2, and 3. We hypothesized that there would be a reduction in vaginal pain scores for the study group vs the control group over the first 72 hours.

STUDY DESIGN

This was a double-blinded, randomized controlled trial that included patients undergoing a posterior colporrhaphy, either independently or in conjunction with other vaginal or abdominal reconstructive procedures. Patients were block randomized to receive 20 mL of either a combination of 1.3% liposomal and 0.25% plain bupivacaine (study) or 20 mL of 0.25% plain bupivacaine (control) in a regional pudendal block before the start of surgery. Double blinding was achieved by covering four 5-mL syringes containing the randomized local anesthetic. After induction of anesthesia, a pudendal nerve block was performed per standard technique (5 mL superiorly and 5 mL inferiorly each ischial spine) using a pudendal kit. The primary outcome was to evaluate postoperative vaginal pain using a visual analog scale on postoperative days 1, 2, and 3. Secondary outcomes included total analgesic medication usage through postoperative day 3, postoperative voiding and defecatory dysfunction, and impact of vaginal pain on quality of life factors.

RESULTS

A total of 120 patients were enrolled (60 in each group). There were no significant differences in demographic data, including baseline vaginal pain (P=.88). Postoperative vaginal pain scores were significantly lower in the combined liposomal and bupivacaine group at all time points vs the plain bupivacaine group. Median pain scores for the study and control groups, respectively, were 0 (0-2) and 2 (0-4) for postoperative day 1 (P=.03), 2 (1-4) and 3 (2-5) for postoperative day 2 (P=.05), and 2 (1-4) and 3 (2-5) for postoperative day 3 (P=.02). Vaginal pain scores increased from postoperative day 1 to postoperative days 2 and 3 in both groups. There was a significant decrease in ibuprofen (P=.01) and acetaminophen (P=.03) usage in the study group; however, there was no difference between groups in total opioid consumption through postoperative day 3 (P=.82). There was no difference in successful voiding trials (study 72%, control 82%, P=.30), return of bowel function (P>.99), or quality of life factors (sleep, stress, mood, and activity).

CONCLUSION

Preoperative regional pudendal block with a combination of liposomal and plain bupivacaine provided more effective vaginal pain control than plain bupivacaine alone for reconstructive surgery that included posterior colporrhaphy. Given the statistically significant decrease in vaginal pain in the study group, this block may be considered as a potential adjunct for multimodal pain reduction in this patient population.

Liposomal Bupivacaine Versus Standard Bupivacaine in the Adductor Canal for Total Knee Arthroplasty: A Randomized, Controlled Trial

Peripheral nerve blocks are commonly used in total knee arthroplasty (TKA). Liposomal bupivacaine is an extended-release anesthetic medication that maintains efficacy upwards of 72 hours. This study compared single-shot liposomal bupivacaine (LB) with the standard single-shot bupivacaine (SB) in a preoperative adductor canal block in TKA patients. A double-blind randomized, controlled trial at a single institution was performed in patients undergoing TKA. A standard preoperative single-shot adductor canal nerve injection was performed in 31 patients using 266 mg of liposomal bupivacaine (20 mL), whereas 32 patients received a standard formulation of 0.5% bupivacaine hydrogen chloride (20 mL). The primary outcome measure was postoperative gait velocity. Secondary outcomes included knee range of motion, pain scores, patient satisfaction, knee extension strength, opioid consumption, length of stay, and adverse events. There were no differences in baseline measures between groups. Improved pain ratings with activity (P=.009) were noted on postoperative day 1 with LB (mean, 4.4; SD, 2.0) compared with SB (mean, 5.9; SD, 2.6). Fewer opioids were used with LB compared with SB on postoperative day 1 (mean, 51.2 vs 66.1; P=.020) and on postoperative day 2 (mean, 39.5 vs 54.8; P=.016). No statistically significant differences in gait velocity, knee range of motion, knee extension strength, or patient satisfaction occurred. Peripheral nerve blockade with a single-shot adductor canal injection demonstrated improved pain scores with activity and diminished postoperative narcotic use when using LB compared with SB in TKA patients. There may be early postoperative advantages with LB as a single-shot injection in adductor canal blockade for patients undergoing TKA. [Orthopedics. 2021;44(4):249-255.].

Updates on Wound Infiltration Use for Postoperative Pain Management: A Narrative Review

Local anesthetic wound infiltration (WI) provides anesthesia for minor surgical procedures and improves postoperative analgesia as part of multimodal analgesia after general or regional anesthesia. Although pre-incisional block is preferable, in practice WI is usually done at the end of surgery. WI performed as a continuous modality reduces analgesics, prolongs the duration of analgesia, and enhances the patient’s mobilization in some cases. WI benefits are documented in open abdominal surgeries (Caesarean section, colorectal surgery, abdominal hysterectomy, herniorrhaphy), laparoscopic cholecystectomy, oncological breast surgeries, laminectomy, hallux valgus surgery, and radical prostatectomy. Surgical site infiltration requires knowledge of anatomy and the pain origin for a procedure, systematic extensive infiltration of local anesthetic in various tissue planes under direct visualization before wound closure or subcutaneously along the incision. Because the incidence of local anesthetic systemic toxicity is 11% after subcutaneous WI, appropriate local anesthetic dosing is crucial. The risk of wound infection is related to the infection incidence after each particular surgery. For WI to fully meet patient and physician expectations, mastery of the technique, patient education, appropriate local anesthetic dosing and management of the surgical wound with “aseptic, non-touch” technique are needed.

Evaluation of bupivacaine liposome injectable suspension efficacy in single-use vials over five days of multiple use

OBJECTIVE

To test the anesthetic effect of a bupivacaine liposome injectable suspension (BLIS), used in a multiple-dose manner for up to 5 consecutive days.

STUDY DESIGN

Prospective, randomized, experimental study.

ANIMALS

A total of 30 male and female Sprague-Dawley rats (Rattus norvegicus), aged 97 (75-130) days and weighing 337.2 (219.6-465.9) g, mean (range).

METHODS

Rats were assigned to one of five BLIS vial groups, in which drug was administered from a newly opened vial or 1, 2, 3 and 4 days after the vial was opened. The vials were refrigerated between uses. A 14 gauge needle attached to an injection plug was used to puncture each vial once and was not removed; BLIS was withdrawn from the injection plug in a multiple-dose fashion. A dose rate of 0.4 mL kg^-1 was administered subcutaneously into the left pelvic limb paw. Antinociception was evaluated using a paw pressure test on both injected and uninjected paws before (time 0, baseline) and 1, 24, 48 and 72 hours after injection.

RESULTS

Age of BLIS vial had no significant effect on anesthetic efficacy (p = 0.97). Across all groups, paw withdrawal latency averaged 5.23 ± 0.24 seconds at baseline (before BLIS injection), increased to 16.45 ± 0.65 seconds at 1 hour after BLIS injection, declined to 7.50 ± 0.76 seconds at 24 hours after BLIS injection, and further declined thereafter (p < 0.001). There was no significant change in paw withdrawal latency in the uninjected paw over time.

CONCLUSIONS AND CLINICAL RELEVANCE

BLIS single-use vials retained efficacy when used up to 5 days in a multiple-dose fashion. Because anesthetic effects declined substantially after 24 hours, multimodal pain management remains important for providing analgesia care.

Pain management after laparoscopic appendectomy: Comparative effectiveness of innovative pre-emptive analgesia using liposomal bupivacaine

BACKGROUND

Laparoscopic appendectomy is standard of care for appendicitis in the US. Pain control that limits opioids is an important area of research given the opioid epidemic. This study examined post-appendectomy inpatient opioid use and pain scores following intraoperative use of liposomal bupivacaine (LB) versus non-liposomal bupivacaine.

METHODS

This was a retrospective cohort study of 155 adults who underwent laparoscopic appendectomy for acute appendicitis. Patients were divided into four cohorts based on the analgesia administered: (i) bupivacaine hydrochloride (BH)± epinephrine; (ii) undiluted LB; (iii) LB diluted with normal saline; and (iv) LB diluted with BH.

RESULTS

Baseline demographic/clinical attributes, intra-operative findings, and post-operative pain scores were equivalent across cohorts. Post-operative pre-discharge opioid use was higher in the BH vs. LB cohorts (mean 60.4 vs. 46.0, 35.5, and 30.4 morphine milligram equivalents, respectively; p < 0.001).

CONCLUSIONS

Pre-emptive analgesia with LB during laparoscopic appendectomy can reduce inpatient opioid use without significantly increasing post-operative pain scores.

Liposomal bupivacaine addition versus standard bupivacaine alone for colorectal surgery: a randomized controlled trial

Aim: This study evaluated use of liposomal bupivacaine (LB) versus standard bupivacaine (SB) alone in quadratus lumborum (QL) blocks for laparoscopic colorectal surgery. Materials & methods: In this prospective, randomized controlled trial, patients received QL1 blocks with either LB (40 ml 0.125% SB plus 20 ml of LB) or SB (60 ml of 0.25% SB) with 30 ml per side. Opioid usage, pain scores, side effects and other medications were recorded. Results: For 78 patients (38 LB; 40 SB), all parameters were similar between groups, except that the LB group had a higher 48 h need for metoclopramide. Conclusion: LB provided no analgesic benefit over SB alone for QL blocks. Clinical Trials registration number: NCT03702621.

Efficacy of liposomal bupivacaine in spine surgery: a systematic review

BACKGROUND CONTEXT

Spine surgery with posterior approaches may involve extensive manipulation of native structures, resulting in significant postoperative pain. Liposomal bupivacaine (LB) is an injectable analgesic that has demonstrated efficacy in decreasing postoperative pain and opioid requirements in patients across multiple surgical subspecialties.

PURPOSE

To consolidate and analyze the findings of retrospective cohort-matched studies and prospective randomized controlled trials investigating the use of LB in spine surgery.

STUDY DESIGN

A systematic review.

STUDY SAMPLE

Retrospective cohort-matched studies and randomized controlled trials (RCTs) investigating the efficacy of injected LB in spinal surgery compared with a control/no treatment group.

METHODS

MEDLINE, Cochrane controlled trials register, and Google Scholar were searched to identify all studies that examined the effect of LB use on outcomes in spine surgery. Our search identified 10 articles that independently evaluated the effect of LB on reduction of postoperative opioid use, pain scores, hospital length of stay, cost, and incidence of adverse effects. The principles of GRADE (Grading of Recommendations, Assessment, Development, and Evaluations) were applied to assess the quality of evidence from each study.

RESULTS

Ten studies were analyzed (1,112 total patients). LB was associated with significantly lower millimolar morphine equivalents (MME) of postoperative opioids, especially in opiate-tolerant patients, visual analog scale (VAS) scores, area under the curve (AUC) of cumulative pain scores, numeric pain scale scores, and hospital length of stay (LOS), with comparable or lower odds of adverse effects relative to controls.

CONCLUSIONS

Low-quality evidence suggests that liposomal bupivacaine may safely decrease postoperative opioid requirements, pain scores, and length of stay in patients undergoing spine surgery, whereas moderate-quality evidence does not support its use at this time. Therefore, additional standardized well-powered prospective studies are necessary to more clearly assess the efficacy of LB in spine surgery.