Safety of liposome extended-release bupivacaine for postoperative pain control

A Network Meta-Analysis of Randomized Controlled Trials Assessing Intraoperative Anesthetic Therapies for Analgesic Efficacy and Morphine Consumption Following Total Knee Arthroplasty

BACKGROUND

The purpose of this study was to compare intraoperative anesthetic therapies for total knee arthroplasty (TKA) regarding postoperative analgesic efficacy and morphine consumption by conducting a systematic literature search.

METHODS

Randomized controlled trials of TKA using various anesthetic therapies were identified from various databases from conception through December 31, 2021. A network meta-analysis of relevant literature was performed to investigate which treatment showed better outcomes. In total, 40 trials were included in this study.

RESULTS

Surface under the cumulative ranking curve showed local infiltration anesthesia (LIA) with saphenous nerve block (SNB) to produce the best pain relief on postoperative days (PODs) 1 and 2 and the best reduction of morphine consumption on PODs 1 and 3. However, femoral nerve block showed the largest effect on pain relief on POD 3, and liposomal bupivacaine showed the largest effect on reduction of morphine consumption on POD 2.

CONCLUSIONS

According to this network meta-analysis, surface under the cumulative ranking curve percentage showed that LIA with SNB provided the best analgesic effect after TKA. Furthermore, patients receiving LIA with SNB had the lowest consumption of morphine. Although femoral nerve block resulted in better pain relief on POD 3, LIA with SNB could be selected first when trying to reduce morphine consumption or increase early ambulation.

Postoperative analgesic options after spine surgery: finding the optimal treatment strategies

INTRODUCTION

Spine surgery is one of the most common types of surgeries performed in the United States; however, managing postoperative pain following spine surgery has proven to be challenging. Patients with spine pathologies have higher incidences of chronic pain and resultant opioid use and potential for tolerance. Implementing a multimodal plan for postoperative analgesia after spine surgery can lead to enhanced recovery and outcomes.

AREAS COVERED

This review presents several options for analgesia following spine surgery with an emphasis on multimodal techniques to best aid this specific patient population. In addition to traditional therapeutics, such as acetaminophen, non-steroidal anti-inflammatory medications, and opioids, we discuss intrathecal morphine administration and emerging regional anesthesia techniques.

EXPERT OPINION

Several adjuncts to improve analgesia following spine surgery are efficacious in the postoperative period. Intrathecal morphine provides sustained analgesia and can be instilled intraoperatively by the surgical team under direct visualization. Local anesthetics deposited under ultrasound guidance by an anesthesiologist trained in regional techniques also provide the opportunity for single injections or continuous analgesia via an indwelling catheter.

YTHDF1-mediated sphingosine kinase 2 upregulation alleviates bupivacaine-induced neurotoxicity via the PI3K/AKT axis

BACKGROUND

Bupivacaine (BUP), a long-acting local anesthetic, has been widely used in analgesia and anesthesia. However, evidence strongly suggests that excessive application of BUP may lead to neurotoxicity in neurons. Sphingosine kinase 2 (SPHK2) has been reported to exert neuroprotective effects. In this study, we intended to investigate the potential role and mechanism of SPHK2 in BUP-induced neurotoxicity in dorsal root ganglion (DRG) neurons.

METHODS

DRG neurons were cultured with BUP to simulate BUP-induced neurotoxicity in vitro. CCK-8, LDH, and flow cytometry assays were performed to detect the viability, LDH activity, and apoptosis of DRG neurons. RT-qPCR and western blotting was applied to measure gene and protein expression. Levels. MeRIP-qPCR was applied for quantification of m6A modification. RIP-qPCR was used to analyze the interaction between SPHK2 and YTHDF1.

RESULTS

SPHK2 expression significantly declined in DRG neurons upon exposure to BUP. BUP challenge substantially reduced the cell viability and increased the apoptosis rate in DRG neurons, which was partly abolished by SPHK2 upregulation. YTHDF1, an N6-methyladenosine (m6A) reader, promoted SPHK2 expression in BUP-treated DRG neurons in an m6A-dependent manner. YTHDF1 knockdown partly eliminated the increase in SPHK2 protein level and the protection against BUP-triggered neurotoxicity in DRG neurons mediated by SPHK2 overexpression. Moreover, SPHK2 activated the PI3K/AKT signaling to protect against BUP-induced cytotoxic effects on DRG neurons.

CONCLUSIONS

In sum, YTHDF1-mediated SPHK2 upregulation ameliorated BUP-induced neurotoxicity in DRG neurons via promoting activation of the PI3K/AKT signaling pathway.

Repurposing of parenterally administered active substances used to treat pain both systemically and locally

Pain is a constant in our lives. The efficacy of drug therapy administered by the parenteral route is often limited either by the physicochemical characteristics of the drug itself or its adsorption-distribution-metabolism-excretion (ADME) mechanisms. One promising alternative is the design of innovative drug delivery systems that can improve the pharmacokinetics |(PK) and/or reduce the toxicity of traditionally used drugs. In this review, we discuss several products that have been approved by the main regulatory agencies (i.e., nano- and microsystems, implants, and oil-based solutions), highlighting the newest technologies that govern both locally and systemically the delivery of drugs. Finally, we also discuss the risk assessment of the scale-up process required, given the impact that this approach could have on drug manufacturing. Teaser: The management of pain by way of the parenteral route can be improved using complex drug delivery systems (e.g., micro- and nanosystems) which require high-level assessment and shorten the regulatory pathway.

Will the Use of Intraoperative Liposomal Bupivacaine During Thumb Carpometacarpal Arthroplasty Decrease Postoperative Use of Opioids? A Prospective Randomized Study

PURPOSE

This study evaluated the use of intraoperative local injection of liposomal bupivacaine to decrease opioid use in the early postoperative period for patients undergoing outpatient thumb carpometacarpal joint arthroplasty.

METHODS

A prospective, randomized, controlled, single-blinded study was designed to compare 2 groups of patients for opioid use, pain scores, and nonopioid pill consumption within 5 days after surgery. The investigational group received an intraoperative injection of 10 ml (133 mg) liposomal bupivacaine. The control group received no local anesthetic. All patients were anesthetized with a standardized supraclavicular nerve block and were prescribed equal amounts of oral narcotic analgesic. Outcomes were assessed by collecting the data from postoperative patient-reported diaries.

RESULTS

The experimental group reported a significantly lower total opioid consumption for the 5 days after surgery. Daily opioid use, as measured by both opioid pill equivalent count and morphine milligram equivalent in addition to postoperative pain scores and nonopioid pill consumption, was not different between groups.

CONCLUSIONS

Intraoperative injection of liposomal bupivacaine was shown to decrease total opioid intake during the 5 days after thumb carpometacarpal arthroplasty.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic II.

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.

Prolonged anesthesia and decreased toxicity of enantiomeric-excess bupivacaine loaded in ionic gradient liposomes

Bupivacaine is the most employed local anesthetic in surgical procedures, worldwide. Its systemic toxicity has directed the synthesis of the less toxic, S(-) enantiomer. This work describes a formulation of ionic gradient liposomes (IGL) containing _S75BVC, an enantiomeric excess mixture of 75% S(-) and 25% R(+) bupivacaine. IGL prepared with 250 mM (NH₄)₂SO₄ in the inner aqueous core of phosphatidylcholine and cholesterol (3:2 mol%) vesicles plus 0.5% _S75BVC showed average sizes of 312.5 ± 4.5 nm, low polydispersity (PDI < 0.18), negative zeta potentials (-14.2 ± 0.2 mV) and were stable for 360 days. The encapsulation efficiency achieved with IGL_S75BVC (%EE = 38.6%) was higher than with IGL prepared with racemic bupivacaine (IGL_RBVC, %EE = 28.3%). TEM images revealed spherical vesicles and µDSC analysis provided evidence on the interaction of the anesthetic with the lipid bilayer. Then, in vitro - release kinetics and cytotoxicity- and in vivo - toxic effects in Zebrafish and biochemical/histopathological analysis plus analgesia in Wistar rats - tests were performed. IGL_S75BVC exhibited negligible toxicity against Schwann cells and Zebrafish larvae, and it did not affect biochemical markers or the morphology of rat tissues (heart, brain, cerebellum, sciatic nerve). The in vitro release of _S75BVC from IGL was extended from 4 to 24 h, justifying the prolonged anesthetic effect measured in rats (~9 h). The advantages of IGL_S75BVC formulation over IGL_RBVC and plain bupivacaine formulations (prolonged anesthesia, preferential sensorial blockade, and no toxicity) confirm its potential for clinical use in surgical anesthesia.

Clinical Effectiveness of Liposomal Bupivacaine Administered by Infiltration or Peripheral Nerve Block to Treat Postoperative Pain

The authors provide a comprehensive summary of all randomized, controlled trials (n = 76) involving the clinical administration of liposomal bupivacaine (Exparel; Pacira Pharmaceuticals, USA) to control postoperative pain that are currently published. When infiltrated surgically and compared with unencapsulated bupivacaine or ropivacaine, only 11% of trials (4 of 36) reported a clinically relevant and statistically significant improvement in the primary outcome favoring liposomal bupivacaine. Ninety-two percent of trials (11 of 12) suggested a peripheral nerve block with unencapsulated bupivacaine provides superior analgesia to infiltrated liposomal bupivacaine. Results were mixed for the 16 trials comparing liposomal and unencapsulated bupivacaine, both within peripheral nerve blocks. Overall, of the trials deemed at high risk for bias, 84% (16 of 19) reported statistically significant differences for their primary outcome measure(s) compared with only 14% (4 of 28) of those with a low risk of bias. The preponderance of evidence fails to support the routine use of liposomal bupivacaine over standard local anesthetics.

Analgesic effect of single-shot ropivacaine at different layers of the surgical site in primary total hip arthroplasty: a randomised, controlled, observer-blinded study

Objectives

The aim of this study was to evaluate the efficacy of local infiltration anaesthesia (LIA) during primary total hip arthroplasty (THA) via a posterolateral approach under general anaesthesia and to compare the efficacy of LIA in all layers with LIA in the deep and superficial fascia.

Patients and methods

One hundred twenty patients were randomised into three groups: LIA in the deep and superficial fascia (group A), LIA in all layers (group B) and the control (group C). The primary outcomes were the visual analogue scale (VAS) pain scores at rest and on movement within 72 h (h) postoperatively. The secondary outcomes included opioid consumption, patient satisfaction, range of motion (ROM), straight leg raise completion rate, length of hospital stay, opioid-related side effects and wound complications. We followed the patients until 6 months after discharge.

Results

At 2 and 6 h, groups A and B had lower resting VAS scores than group C (p < 0.01); at 12 h, group B had a lower resting VAS score than group C (p < 0.05). At 6 and 12 h, the movement VAS scores in groups A and B were lower than those in group C (p < 0.01). Groups A and B had similar VAS scores during the observation period. Groups A and B had higher levels of patient satisfaction than group C (p = 0.03 and p = 0.018, respectively). Opioid consumption was similar in the three groups. There were no significant differences in the other secondary outcomes amongst the three groups. No difference was found in hip rehabilitation or chronic pain during the follow-up period.

Conclusion

Single-shot LIA with ropivacaine alone reduces the pain score during the first 12 postoperative hours and improves patients’ satisfaction with THA. LIA in the deep and superficial fascia and LIA in all layers have similar analgesic effects. LIA in the deep and superficial fascia may be an alternative method to LIA in all layers.

Bupivacaine Pharmacokinetics and Breast Milk Excretion of Liposomal Bupivacaine Administered After Cesarean Birth

Very little plasma bupivacaine was transferred into breast milk after liposomal bupivacaine wound infiltration in patients who had undergone cesarean delivery.

To evaluate bupivacaine concentrations in maternal plasma and transfer into breast milk in women undergoing liposomal bupivacaine infiltration in the transversus abdominis plane after cesarean birth.

Risk factors for complications and return to the emergency department after interscalene block using liposomal bupivacaine for shoulder surgery

BACKGROUND

Exparel (liposomal bupivacaine) has recently gained favor for use in interscalene regional blocks for shoulder surgery. While effective for pain relief, this does have adverse effects that can lead to postoperative emergency department (ED) visits. This study aimed to identify any patient risk factors that are associated with complications leading to ED return visits owing to interscalene blocks using Exparel before shoulder surgery.

METHODS

A retrospective chart review was performed for all patients undergoing shoulder surgery with an Exparel interscalene block in an 8-month period. For each patient, demographic information, comorbidities, type of block, postoperative complications, ED return visits, and readmissions were recorded. The 5-factor modified Frailty Index score and the Charlson Comorbidity Index score were calculated. Univariate and multivariate logistic regressions were conducted to identify risk factors associated with increased complications and return to the ED.

RESULTS

Overall, 352 patients were included; most patients were men, were aged between 51 and 70 years, and had a body mass index of 25.0-35.0. Postoperative complications related to the Exparel interscalene block occurred in 58 patients (16.5%), including 37 minor complications (10.5%) and 21 major complications (6.0%) that led to return ED visits. Univariate analysis yielded American Society of Anesthesiologists (ASA) score (P = .03) as a significant predictor of minor complications. Multivariate logistic regression analysis yielded ASA score (P = .096; odds ratio, 1.64) as trending toward being a significant risk factor for minor complications. Univariate analysis yielded age (P = .006), ASA score (P = .009), and Charlson Comorbidity Index score (P = .002) as significant predictors of major complications. Multivariate logistic regression analysis yielded ASA score (P = .049; odds ratio, 2.25) as the only significant risk factor for major complications.

CONCLUSION

Surgeons and anesthesiologists should strongly consider a patient's ASA score, in addition to his or her pulmonary and cardiac history, when deciding whether the patient is an appropriate candidate for an interscalene regional block using Exparel for shoulder surgery.

Unintentional Epidural Anesthesia Mimicking Cauda Equina Syndrome from Suprafascial Injection of Liposomal Bupivacaine After Lumbar Foraminotomy: A Case Report

CASE

This case report describes a 46-year-old woman undergoing right-sided L5 to S1 decompression who received liposomal bupivacaine (LB) for postoperative analgesia and developed unintentional epidural anesthesia with symptoms mimicking cauda equina syndrome. The patient's symptoms resolved 72 hours postoperatively, approximately the length that LB typically lasts. At the 16-month follow-up, the patient demonstrated complete neurological function with no lower extremity strength or sensation deficits.

CONCLUSIONS

Tracking of LB into the epidural space after lumbar surgery may cause transient epidural anesthesia with symptoms that mimic cauda equina syndrome.

Local Anesthetics: Pharmacology and Special Preparations

Local anesthetics are the only class of drugs that can block transduction and transmission of nociception. Physical properties, mechanism of action, and pharmacokinetics of this class of drugs are reviewed in this article. The clinical use, such intravenous administration of lidocaine, and local and systemic toxic effects are covered. A review of current studies published in the human and veterinary literature on lidocaine patches (Lidoderm) and liposomal bupivacaine (Experal and Nocita) are discussed.

Can Liposomal Bupivacaine Be Safely Utilized in Elective Spine Surgery?

STUDY DESIGN

Single-blinded prospective randomized control trial.

OBJECTIVES

To compare the incidence of adverse events (AEs) and hospital length of stay between patients who received liposomal bupivacaine (LB) versus a single saline injection, following posterior lumbar decompression and fusion surgery for degenerative spondylosis.

METHODS

From 2015 to 2016, 59 patients undergoing posterior lumbar decompression and fusion surgery were prospectively enrolled and randomized to receive either 60 mL injection of 266 mg LB or 60 mL of 0.9% sterile saline, intraoperatively. Outcome measures included the incidence of postoperative AEs and hospital length of stay.

RESULTS

The most common AEs in the treatment group were nausea (39.3%), emesis (18.1%), and hypotension (18.1%). Nausea (23%), constipation (19.2%), and urinary retention (15.3%) were most common in the control group. Patients who received LB had an increased risk of developing nausea (relative risk [RR] = 1.7; 95% confidence interval [CI] = 0.75-3.8), emesis (RR = 2.3; 95% CI = 0.51-10.7), and headaches (RR = 2.36; 95% CI = 0.26-21.4). Patients receiving LB had a decreased risk of developing constipation (RR = 0.78; 95% CI = 0.25-2.43), urinary retention (RR = 0.78; 95% CI = 0.21-2.85), and pruritus (RR = 0.78; 95% = 0.21-2.8) postoperatively. Relative risk values mentioned above failed to reach statistical significance. No significant difference in the hospital length of stay between both groups was found (3.9 vs 3.9 days; P = .92).

CONCLUSION

Single-dose injections of LB to the surgical site prior to wound closure did not significantly increase or decrease the incidence or risk of developing AEs postoperatively. Furthermore, no significant difference was found in the hospital length of stay between both groups.

Nanotechnology: A Promising New Paradigm for the Control of Pain

Objective

The objective of this article is to critically review both preclinical and clinical studies that focus on the use of nanotechnology for both acute and chronic pain management, surveying both diagnostic and therapeutic applications. The article also provides information on nanotechnology for pain practitioners, so that they may better understand how this technology works and how it may be applied to their day-to-day clinical practice.

Study Design

Narrative review.

Methods

The Pubmed NCBI and EMBASE databases were utilized to review published reports of in vivo and clinical studies that focus on using nanotechnology for pain management applications in both the acute and chronic pain settings.

Results

Articles were screened by title, abstract, and full article review. They were then analyzed by specific clinical indications, and appropriate data were presented based on a critical analysis of those articles.

Conclusions

As the development of nanomedical applications in acute and chronic pain management continues, medical practitioners should consider their growing potential to enhance the care of patients who are consistently living with pain. Current barriers to implementation include manufacturing scale-up for commercial viability, long-term nanoparticle toxicity considerations, and high cost for successful passage through clinical trials. These challenges will need to be overcome with ongoing translational research efforts in collaboration with industry and government bodies such as the Food and Drug Administration (FDA).

Extended Release Liposomal Bupivacaine Injection (Exparel) for Early Postoperative Pain Control Following Palatoplasty

INTRODUCTION

Liposomal bupivacaine (LB) is a long-acting local anesthetic reported to decrease postoperative pain in adults. The authors demonstrate the safe use of LB in pediatric patients with improved pain control following palatoplasty.

MATERIALS AND METHODS

Retrospective patient series of all single-surgeon palatoplasty patients treated at a tertiary craniofacial center from August 2014 to December 2015 were included. All patients received 1.3% LB intraoperatively as greater palatal nerve and surgical field blocks in 2-flap V-Y pushback palatoplasty. Postoperative oral intake, opioids administered, duration of hospitalization, and FLACC (face, legs, activity, cry, consolability) pain scores were measured.

RESULTS

Twenty-seven patients (16 males and 11 females, average age of 10.8 months, weight 8.8 kg) received 2.9 ± 0.9 mL (2.6 ± 1.9 mg/kg) 1.3% LB. Average FLACC scores were 2.4 ± 2.2/10 in the postanesthesia care unit and 3.8 ± 1.8/10 while inpatients. Oral intake was first tolerated 10.3 ± 11.5 hours postoperatively and tolerated 496.4 ± 354.2 mL orally in the first 24 hours postoperatively. Patients received 8.5 ± 8.4 mg hydrocodone equivalents (0.46 ± 0.45 mg/kg per d hydrocodone equivalents) and were discharged 2.1 ± 1.3 days postoperatively. Opioid-related adverse events included emesis in 7.4% and pruritis in 3.7% of patients.

CONCLUSIONS

The LB may be used safely in pediatric patients. Intraoperative injection of LB during palatoplasty can yield low postoperative opioid use and an early and adequate volume of oral intake over an average hospital stay. Further cost-efficacy studies of LB are needed to assess its value in pediatric plastic surgery.

Delivery systems of local anesthetics in bone surgery: are they efficient and safe?

Management of postoperative pain following bone surgery includes administration of local anesthetics (LAs). Smart delivery systems, including triggered systems, have been designed to provide a continuous release of LA in situ. However, these systems can provide a high level of LA locally. This review will examine the state-of-the-art regarding the LA delivery systems optimized for management of postoperative pain in bone surgery and will discuss the potential adverse effects of LAs on the overall pathways of bone healing, including the inflammation response phase, hemostasis phase, tissue repair phase and remodeling phase. There is a clinical need to document these effects and the potential impacts on the clinical outcome of the patient.

Thumb Basal Joint Arthroplasty: Prospective Comparison of Perioperative Analgesia and Opioid Consumption

Trapeziectomy alone or in combination with a suspensionplasty technique is a common surgical treatment for symptomatic thumb basal joint arthritis. The authors undertook a prospective comparative study to test the hypothesis that peripheral nerve blocks would provide better pain control than local anesthesia with bupivacaine or liposomal bupivacaine regarding pain scores and opioid pill consumption. Patients who elected to undergo basal joint arthroplasty were allocated to 1 of 3 postoperative pain management groups: (1) peripheral nerve block, (2) local anesthesia with bupivacaine, or (3) local anesthesia with liposomal bupivacaine. Total opioid pill consumption and visual analog scale pain scores were reported for the first 5 postoperative days (PODs). Seventy-eight patients were enrolled, with 27, 23, and 28 patients in the peripheral nerve block, bupivacaine, and liposomal bupivacaine groups, respectively. All groups experienced an increase in opioid pill consumption and visual analog scale pain scores from POD 0 to POD 1. Postoperative visual analog scale pain scores were lowest in group 3 from POD 0 to POD 2. Average visual analog scale pain scores were highest in group 1, except for on POD 0. After POD 2, visual analog scale pain scores normalized between all groups and decreased uniformly thereafter. Total opioid consumption was lowest in group 3 (average, 11 pills) compared with group 1 (average, 17 pills) and group 2 (average, 19 pills). Overall, these findings did not support the authors' hypothesis that peripheral nerve blocks are superior in terms of postoperative pain control and opioid consumption. Although there were advantages regarding opioid consumption and pain control with liposomal bupivacaine, these were limited to the first POD. The effectiveness of each modality, as well as potential risks and costs, should be considered when determining the optimal strategy. [Orthopedics. 2018; 41(3):e410-e415.].

Defining local nerve blocks for feline distal pelvic limb surgery: a cadaveric study

Objectives Anatomical and methodological detail is lacking regarding local anesthetic peripheral nerve block techniques for distal pelvic limb surgery in cats. The aim of this study was to develop, describe and test nerve block methods based on cadaveric dissections and dye injections. Methods Ten pairs of feline pelvic limbs (n = 20) were dissected and the tibial nerve (T n.), common fibular (peroneal) nerve (CF n., and its two branches, the superficial fibular [peroneal] nerve [SpF n.] and the deep fibular [peroneal] nerve [DpF n.]) and the saphenous nerve (Sa n.) were identified. Based on these dissections, a 'distal crus block' (selective blockade of the CF n., T n. and Sa n.) and a 'distal pes block' (selective blockade of the SpF n., DpF n., T n. and Sa n.) were developed for surgical procedures in two different regions of the distal pelvic limb. Techniques were tested using new methylene blue (NMB) dye injections in feline pelvic limbs (n = 12). Using a 25 G × 5/8 inch needle and 1 ml syringe, 0.1 ml/kg of NMB dye solution was injected at the site of the CF n., and 0.05 ml/kg was injected at the sites of the SpF n., DpF n., Sa n. and T n. The length and circumference (fully or partially stained) of each stained nerve were measured. Results Positive staining of nerves was observed in 12/12 limbs. The lengths stained for the CF n., DpF n., SpF n., Sa n. and T n. were 27.19 ± 7.13, 20.39 ± 5.57, 22.82 ± 7.13, 30.89 ± 6.99 and 25.16 ± 8.09 mm, respectively. The nerves were fully stained in 12, 12, 10, 11 and 11 out of 12 limbs, respectively. Conclusions and relevance These two, three-point injection methods may be an effective perioperative analgesia technique for feline distal pelvic limb procedures.

Advanced Analgesic Drug Delivery and Nanobiotechnology

Transdermal administration of analgesic medications offers several benefits over alternative routes of administration, including a decreased systemic drug load with fewer side effects, and avoidance of drug degradation by the gastrointestinal tract. Transdermal administration also offers a convenient mode of drug administration over an extended period of time, particularly desirable in pain medicine. A transdermal administration route may also offer increased safety for drugs with a narrow therapeutic window. The primary barrier to transdermal drug absorption is the skin itself. Transdermal nanotechnology offers a novel method of achieving enhanced dermal penetration with an extended delivery profile for analgesic drugs, due to their small size and relatively large surface area. Several materials have been used to enhance drug duration and transdermal penetration. The application of nanotechnology in transdermal delivery of analgesics has raised new questions regarding safety and ethical issues. The small molecular size of nanoparticles enables drug delivery to previously inaccessible body sites. To ensure safety, the interaction of nanoparticles with the human body requires further investigation on an individual drug basis, since different formulations have unique properties and side effects.

Role of Periarticular Liposomal Bupivacaine Infiltration in Patients Undergoing Total Knee Arthroplasty-A Meta-analysis of Comparative Trials

BACKGROUND

Over last 2 years, many trials have evaluated newly approved liposomal bupivacaine for periarticular infiltration in total knee arthroplasty (TKA) with mixed results. Our meta-analysis attempts to consolidate the results and make evidence-based conclusions.

METHODS

Trails comparing periarticular infiltration of liposomal bupivacaine to conventional analgesic regimens for total knee arthroplasty published till June 2016 were searched in medical database. Comparisons were made for length of stay (LOS), postoperative pain scores, range of motion, and opioid consumption. Meta-regression was performed for LOS to evaluate various analgesic control subgroups.

RESULTS

Sixteen trials were included in the final analysis. Liposomal bupivacaine group showed a shorter LOS (reported in 13 subgroups) than control group by 0.17 ± 0.04 days (random effects, P < .001, I² = 84.66%). Meta-regression for various types of control showed a predictability (R²) of 73%, τ² = 0.013 (random effects, P < .001, I² = 45.16). Only femoral block subgroup attained statistically significant shorter LOS on splitting the control group. Numeric pain scores were lower for pooled control group and local anesthetic infiltration subgroup in immediate postoperative phase. Second postoperative day analgesia was statistically superior to overall clubbed controls and femoral block subgroup. Superiority and/or inferiority of liposomal bupivacaine could not be proven for opioid consumption and range of motion because of a small pooled sample size. Publication bias is likely for LOS (Egger test, X intercept = 2.42, P < .001).

CONCLUSION

Liposomal bupivacaine infiltration has questionable clinical advantage, as it marginally shortens patient's hospital stay especially in comparison with patients receiving analgesic femoral nerve block. Compared with conventional regimens, it can provide slightly superior yet sustained (till second postoperative day) perioperative analgesia. High heterogeneity suggests need for standardization of infiltration techniques for better predictability of results.

Thoracic epidural catheter for postoperative pain control following an ineffective transversus abdominis plane block using liposome bupivacaine

A 24-year-old female with a history of ulcerative colitis underwent colectomy. The patient received an ineffective transversus abdominis plane (TAP) block with liposome bupivacaine (Exparel) intraoperatively and was started on a hydromorphone patient-controlled analgesia 5 hours after the TAP block, which did not relieve her pain. A continuous thoracic epidural (CTE) was then placed after blood levels of bupivacaine were drawn, and the patient immediately experienced significant pain relief. The combined use of liposome bupivacaine and bupivacaine CTE infusion in the postoperative management of this patient demonstrated no safety concerns, provided excellent analgesia and plasma concentrations of bupivacaine remained far below toxic levels.

An extended release local anaesthetic: potential for future use in veterinary surgical patients?

One of the most effective means of preventing the transduction and transmission of acute and perioperative pain is through the use of local anaesthetics. However, local anaesthetics currently available have a relatively short duration of action. Although there are several tools available to treat perioperative pain in companion animals, overall, there is an unmet need for products that can be administered in the clinic, and provide pain relief for the crucial first few days following surgery in the home environment. Specifically, in relation to local anaesthetics, there is a clear unmet need for a long-acting local anaesthetic that can be added to the multimodal analgesic protocol to provide pain relief to patients in the home environment or during extended hospitalization. Bupivacaine liposomal injectable suspension recently became available for use in humans, and has proven efficacious and safe. This paper will review the use of local anaesthetics, particularly bupivacaine, in dogs and cats, and introduce a new formulation of prolonged release bupivacaine that is in development for dogs and cats.

A Novel Proliposomal Ropivacaine Oil: Pharmacokinetic-Pharmacodynamic Studies After Subcutaneous Administration in Pigs

BACKGROUND

Liposomal local anesthetics are limited by a short liposomal shelf-life, even when under refrigeration. We describe a novel proliposomal ropivacaine that produces liposomes in situ, only after exposure to aqueous media.

METHODS

In vitro: Nanoparticles were assessed (particle size distribution analyzer, cryo-transmission electron microscopy) at baseline and after exposure to saline/plasma.

TOXICITY

In porcine wound healing study (n = 12), healing was assessed by photography, clinical assessment, and histology. Pharmacodynamics: Seventeen young piglets were randomly assigned to plain 0.5% ropivacaine (n = 5), proliposomal 4% ropivacaine (n = 6), or sham (n = 6). Tactile threshold was assessed using von Frey filaments applied to the surgical wound; the nonoperated skin was used as a control. Tactile threshold over time was determined using area under the curve (AUC) and assessed by 1-way analysis of variance.

PHARMACOKINETICS

8 young piglets were randomly assigned to plain 0.5% (25 mg, n = 4) or proliposomal 4% (200 mg, n = 4) ropivacaine. Plasma ropivacaine was assessed by high-performance liquid chromatography at baseline and at intervals over 36 hours. Paired ropivacaine concentration (from wound exudate and plasma) was obtained at 96 hours. Data were analyzed using noncompartmental and compartmental models.

RESULTS

In vitro: On exposure to saline and plasma, the study drug was transformed from a homogenous oil to an emulsion containing liposomes of approximately 1.4-μm diameter; this effect was dilution dependent and stable over time.

TOXICITY

All wounds healed well; no effect of drug group was observed. Pharmacodynamics: Plain and proliposomal ropivacaine provided sensory anesthesia for approximately 6 and 30 hours, respectively. There was an approximately 7-fold increase in the AUC of anesthesia for proliposomal ropivacaine compared with plain ropivacaine (mean difference, 1010; 95% confidence interval [CI], 625-1396 g·h/mm; P < 0.0001).

PHARMACOKINETICS

There was no difference in Cmax (2.31 ± 0.74 vs 2.32 ± 0.46 mg/L), despite an approximately 8-fold difference in dose. However, proliposomal ropivacaine was associated with a marked prolongation of Tmax (6.50 ± 6.35 vs 0.5 ± 0.0 hours), terminal half-life (16.07 ± 5.38 vs 3.46 ± 0.88 hours; P = 0.0036), and ropivacaine-time AUC (47.72 ± 7.16 vs 6.36 ± 2.07 h·mg/L; P < 0.0001), when compared with plain ropivacaine. The proliposomal formulation provided an approximately 250-fold higher ropivacaine concentration in the surgical wound (mean difference, 3783 ng/mL; 95% CI, 1708-5858; P = 0.001) and an approximately 25-fold higher wound:plasma ropivacaine concentration ratio (mean difference, 126; 95% CI 38-213; P = 0.011).

CONCLUSIONS

Proliposomal ropivacaine exerted prolonged anesthesia with delayed elimination, typical for liposomal drugs. The advantage of this novel proliposomal ropivacaine is its ease of preparation and its extended shelf-stability (>2 years) at room temperature.

Use of liposomal bupivacaine in the postoperative management of posterior spinal decompression

OBJECTIVE

The aim in this paper was to evaluate the efficacy of long-acting liposomal bupivacaine in comparison with bupivacaine hydrochloride for lowering postoperative analgesic usage in the management of posterior cervical and lumbar decompression and fusion.

METHODS

A retrospective cohort-matched chart review of 531 consecutive cases over 17 months (October 2013 to February 2015) for posterior cervical and lumbar spinal surgery procedures performed by a single surgeon (J.J.) was performed. Inclusion criteria for the analysis were limited to those patients who received posterior approach decompression and fusion for cervical or lumbar spondylolisthesis and/or stenosis. Patients from October 1, 2013, through December 31, 2013, received periincisional injections of bupivacaine hydrochloride, whereas after January 1, 2014, liposomal bupivacaine was solely administered to all patients undergoing posterior approach cervical and lumbar spinal surgery through the duration of treatment. Patients were separated into 2 groups for further analysis: posterior cervical and posterior lumbar spinal surgery.

RESULTS

One hundred sixteen patients were identified: 52 in the cervical cohort and 64 in the lumbar cohort. For both cervical and lumbar cases, patients who received bupivacaine hydrochloride required approximately twice the adjusted morphine milligram equivalent (MME) per day in comparison with the liposomal bupivacaine groups (5.7 vs 2.7 MME, p = 0.27 [cervical] and 17.3 vs 7.1 MME, p = 0.30 [lumbar]). The amounts of intravenous rescue analgesic requirements were greater for bupivacaine hydrochloride in comparison with liposomal bupivacaine in both the cervical (1.0 vs 0.39 MME, p = 0.31) and lumbar (1.0 vs 0.37 MME, p = 0.08) cohorts as well. None of these differences was found to be statistically significant. There were also no significant differences in lengths of stay, complication rates, or infection rates. A subgroup analysis of both cohorts of opiate-naive versus opiate-dependent patients found that those patients who were naive had no difference in opiate requirements. In chronic opiate users, there was a trend toward higher opiate requirements for the bupivacaine hydrochloride group than for the liposomal bupivacaine group; however, this trend did not achieve statistical significance.

CONCLUSIONS

Liposomal bupivacaine did not appear to significantly decrease perioperative narcotic use or length of hospitalization, although there was a trend toward decreased narcotic use in comparison with bupivacaine hydrochloride. While the results of this study do not support the routine use of liposomal bupivacaine, there may be a benefit in the subgroup of patients who are chronic opiate users. Future prospective randomized controlled trials, ideally with dose-response parameters, must be performed to fully explore the efficacy of liposomal bupivacaine, as the prior literature suggests that clinically relevant effects require a minimum tissue concentration.

Liposomal bupivacaine for regional anesthesia

PURPOSE OF REVIEW

Using a regional block in a multimodal approach to postoperative analgesia management involves addressing, which local anesthetic and how much should be used to ensure adequate pain relief to reduce related morbidity and mortality. This article will review literature surrounding the recently approved formulation of slow release liposomal bupivacaine, define its proven benefits, and identify ongoing studies to further examine the utility of this novel formulation by various routes.

RECENT FINDINGS

Recent Phase II and III clinical trials have demonstrated the ability of liposomal bupivacaine to provide prolonged analgesia, maintain a high safety profile in therapeutic doses, and decrease opioid requirements when compared with placebo in local infiltration applications for up to 24 h. Between 24 and 72 h after study drug administration, there was minimal to no difference between EXPAREL and placebo treatments on mean pain intensity. Conventional bupivacaine or ropivacaine groups (current standard practice in many hospitals in the USA) were not compared. In addition, the analgesic efficacy, cost-effectiveness, and safety profile of liposomal bupivacaine has not thoroughly been studied in various standard clinical settings such as perineural, intrathecal, and epidural administration.

SUMMARY

Current published data do not provide superior clinical results for EXPAREL over conventional bupivacaine based upon the lack of adequately powered multicentered clinical trials with comparison groups. Further investigation is necessary to identify the analgesic efficacy and safety profile of liposomal bupivacaine versus standard local anesthetics and to define the optimal clinical indication for liposomal bupivacaine administration in regional anesthesia.

Wide Awake Trigger Finger Release Surgery: Prospective Comparison of Lidocaine, Marcaine, and Exparel

BACKGROUND

Local anesthetics are routinely used in hand surgery for procedures such as trigger finger releases (TFRs). However, little is known as to the difference in efficacy and patient experience with various local anesthetics. We prospectively evaluated the efficacy of Lidocaine (L), Marcaine (M), and Exparel (E) to elucidate differences in pain scores and opioid consumption between these groups.

METHODS

All consecutive TFR performed over a 6-month period in 2014 at our institution were divided to receive Lidocaine, Marcaine, or Marcaine with postoperative Exparel. Pain levels, daily opioid consumption, and adverse reactions were recorded and analyzed for postoperative day (POD) 0-3.

RESULTS

A total of 154 patients were enrolled (L:53, M:50, E:51). The Lidocaine group reported the highest pain levels for POD 0-1. Marcaine pain levels were similar to Exparel on POD 0 but higher on POD 1. Opioid consumption on POD 0-1 was significantly different with E:27%, M:58% and L:59% as was the number of pills consumed (E:0.70, M: 1.08 and L:1.62). In addition, 50% of Exparel patients required no pain medications and experienced significantly less adverse reactions (E:4%, M:10%, L:13%). By POD 2-3, there were no statistical differences between the 3 groups.

CONCLUSIONS

Patients treated with Marcaine attain better pain control than Lidocaine on POD 0-1but only patients who received Exparel maintained the lowest pain levels through POD 0-3 while using little-to-no opioid medications and with less adverse reactions than Lidocaine or Marcaine alone.

Local bupivacaine for postoperative pain management in thyroidectomized patients: A prospective and controlled clinical study

OBJECTIVE

We aimed to evaluate the effect of bupivacaine and to compare the routes of administration of bupivacaine in the management of postoperative incision site pain after thyroidectomy.

MATERIAL AND METHODS

Consecutive patients who were planned for thyroidectomy surgery were randomized into three groups of 30 patients each: Group 1 (control group): standard thyroidectomy surgery without additional intervention; Group 2 (paratracheal infiltration with bupivacaine): following thyroidectomy, 0.25% bupivacaine was applied on the surgical area; Group 3 (subcutaneous infiltration with bupivacaine): following thyroidectomy, 0.25% bupivacaine was injected into the cutaneous, subcutaneous region and fascia of the surgical area. Postoperative pain was evaluated by a visual analog scale (VAS) at 1(st), 4(th), and 12(th) hours after thyroidectomy. Total daily requirement for additional analgesia was recorded.

RESULTS

The mean age of 90 patients was 44.37±13.42 years, and the female:male ratio was 62:28. There was no difference between study groups in terms of age, thyroid volume, TSH and T4 levels. VAS score of patients in paratracheal infiltration with bupivacaine group was significantly lower than control group patients at 1(st), 4(th) and 12(th) hours following thyroidectomy (p=0.030, p=0.033, p=0.039, respectively). The need for analgesics was significantly lower in both paratracheal infiltration and subcutaneous infiltration groups than the control group (86.7%, 83.0%, and 73.3%, respectively, p=0.049).

CONCLUSIONS

Intraoperative local bupivacaine application is effective in decreasing postoperative pain in patients with thyroidectomy.

Pain management strategies in hand surgery

Modern anesthetic agents have allowed for the rapid expansion of ambulatory surgery, particularly in hand surgery. The choice between general anesthesia, peripheral regional blocks, regional intravenous anesthesia (Bier block), local block with sedation, and the recently popularized wide-awake hand surgery depends on several variables, including the type and duration of the procedure and patient characteristics, coexisting conditions, location, and expected length of the procedure. This article discusses the various perioperative and postoperative analgesic options to optimize the hand surgical patients' experience.

Postoperative Pain and Length of Stay Lowered by Use of Exparel in Immediate, Implant-Based Breast Reconstruction

Background:

Patients undergoing mastectomy and prosthetic breast reconstruction have significant acute postsurgical pain, routinely mandating inpatient hospitalization. Liposomal bupivacaine (LB) (Exparel; Pacira Pharmaceuticals, Inc., Parsippany, N.J.) has been shown to be a safe and effective pain reliever in the immediate postoperative period and may be advantageous for use in mastectomy and breast reconstruction patients.

Methods:

Retrospective review of 90 immediate implant-based breast reconstruction patient charts was completed. Patients were separated into 3 groups of 30 consecutively treated patients who received 1 of 3 pain treatment modalities: intravenous/oral narcotic pain control (control), bupivacaine pain pump, or LB injection. Length of hospital stay, patient-reported Visual Analog Scale (VAS) pain scores, postoperative patient-controlled analgesia usage, and nausea-related medication use were abstracted and subjected to analysis of variance and multiple linear-regression analysis, as appropriate.

Results:

Subjects were well-matched for age (P = 0.24) regardless of pain-control modality. Roughly half (53%) of control and pain pump–treated subjects had bilateral procedures, as opposed to 80% of LB subjects. Mean length of stay for LB subjects was significantly less than control (1.5 days vs 2.00 days; P = 0.016). LB subjects reported significantly lower VAS pain scores at 4, 8, 12, 16, and 24 hours compared with pain pump and control (P < 0.01). There were no adverse events in the LB group.

Conclusion:

Use of LB in this group of immediate breast reconstruction patients was associated with decreased patient VAS pain scores in the immediate postoperative period compared with bupivacaine pain pump and intravenous/oral narcotic pain management and reduced inpatient length of stay.

Unanticipated transient sciatic nerve deficits from intra-wound liposomal bupivacaine injection during total hip arthroplasty

Liposomal bupivacaine (Exparel^®) is a novel formulation of local anesthetic used to provide extended postoperative analgesia as part of a multimodal pain control regimen in patients undergoing total joint arthroplasty. In the three total hip arthroplasty cases described, all patients exhibited a transient loss of neurologic function in the sciatic nerve distribution of the operated extremity lasting between 24 and 72 h during the immediate postoperative period. Due to the nature and duration of the deficits, it was concluded that they likely occurred as a result of unintended injection of the medication in close proximity to the sciatic nerve. To the best of our knowledge, these events have yet to be reported in the current literature. We recommend orthopaedic surgeons pay special attention during infiltration of the medication at the surgical site to avoid postoperative neurological deficits.

Stimuli-responsive liposomes for the delivery of nucleic acid therapeutics

Nucleic acid therapeutics (NATs) are valuable tools in the modulation of gene expression in a highly specific manner. So far, NATs have been actively pursued in both pre-clinical and clinical studies to treat diseases such as cancer, infectious and inflammatory diseases. However, the clinical application of NATs remains a considerable challenge owing to their limited cellular uptake, low biological stability, off-target effect, and unfavorable pharmacokinetics. One concept to address these issues is to deliver NATs within stimuli-responsive liposomes, which release their contents of NATs upon encountering environmental changes such as temperature, pH, and ion strength. In this case, before reaching the targeted tissue/organ, NATs are protected from degradation by enzymes and immune system. Once at the area of interest, localized and targeted delivery can be achieved with minimal influence to other parts of the body. Here, we discuss the latest developments and existing challenges in this field.

FROM THE CLINICAL EDITOR

Nucleic acid therapeutics have been shown to enhance or eliminate specific gene expression in experimental research. Unfortunately, clinical applications have so far not been realized due to problems of easy degradation and possible toxicity. The use of nanosized carriers such as liposomes to deliver nucleic acids is one solution to overcome these problems. In this review article the authors describe and discuss the potentials of various trigger-responsive "smart" liposomes, with a view to help other researchers to design better liposomal nucleic acid delivery systems.