HTX-011 reduced pain intensity and opioid consumption versus bupivacaine HCl in herniorrhaphy: results from the phase 3 EPOCH 2 study

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

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

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.

Nanotechnology for Pain Management

Introduction: In the context of the current opioid crisis, non-pharmacologic approaches to pain management have been considered important alternatives to the use of opioids or analgesics. Advancements in nano and quantum technology have led to the development of several nanotransporters, including nanoparticles, micelles, quantum dots, liposomes, nanofibers, and nano-scaffolds. These modes of nanotransporters have led to the development of new drug formulations. In pain medicine, new liposome formulations led to the development of DepoFoam™ introduced by Pacira Pharmaceutical, Inc. (Parsippany, NJ, USA). This formulation is the base of DepoDur™, which comprises a combination of liposomes and extended-release morphine, and Exparel™, which comprises a combination of liposomes and extended-release bupivacaine. In 2021, Heron Therapeutics (San Diego, CA, USA) created Zynrelef™, a mixture of bupivacaine and meloxicam. Advancements in nanotechnology have led to the development of devices/patches containing millions of nanocapacitors. Data suggest that these nanotechnology-based devices/patches reduce acute and chronic pain. Methods: Google and PubMed searches were conducted to identify studies, case reports, and reviews of medical nanotechnology applications with a special focus on acute and chronic pain. This search was based on the use of keywords like nanotechnology, nano and quantum technology, nanoparticles, micelles, quantum dots, liposomes, nanofibers, nano-scaffolds, acute and chronic pain, and analgesics. This review focuses on the role of nanotechnology in acute and chronic pain. Results: (1) Nanotechnology-based transporters. DepoDur™, administered epidurally in 15, 20, or 25 mg single doses, has been demonstrated to produce significant analgesia lasting up to 48 h. Exparel™ is infiltrated at the surgical site at the recommended dose of 106 mg for bunionectomy, 266 mg for hemorrhoidectomy, 133 mg for shoulder surgery, and 266 mg for total knee arthroplasty (TKA). Exparel™ is also approved for peripheral nerve blocks, including interscalene, sciatic at the popliteal fossa, and adductor canal blocks. The injection of Exparel™ is usually preceded by an injection of plain bupivacaine to initiate analgesia before bupivacaine is released in enough quantity from the depofoarm to be pharmacodynamically effective. Finally, Zynrelef™ is applied at the surgical site during closure. It was initially approved for open inguinal hernia, abdominal surgery requiring a small-to-medium incision, foot surgery, and TKA. (2) Nanotechnology-based devices/patches. Two studies support the use of nanocapacitor-based devices/patches for the management of acute and chronic pain. A randomized study conducted on patients undergoing unilateral primary total knee (TKA) and total hip arthroplasty (THA) provided insight into the potential value of nanocapacitor-based technology for the control of postoperative acute pain. The results were based on 2 studies, one observational and one randomized. The observational study was conducted in 128 patients experiencing chronic pain for at least one year. This study suggested that compared to baseline, the application of a nanocapacitor-based Kailo™ pain relief patch on the pain site for 30 days led to a time-dependent decrease in pain and analgesic use and an increase in well-being. The randomized study compared the effects of standard of care treatment to those of the same standard of care approach plus the use of two nanocapacitor-based device/patches (NeuroCuple™ device) placed in the recovery room and kept in place for three days. The study demonstrated that the use of the two NeuroCuple™ devices was associated with a 41% reduction in pain at rest and a 52% decrease in the number of opioid refills requested by patients over the first 30 days after discharge from the hospital. Discussion: For the management of pain, the use of nano-based technology has led to the development of nano transporters, especially focus on the use of liposome and nanocapacitors. The use of liposome led to the development of DepoDur™, bupivacaine Exparel™ and a mixture of bupivacaine and meloxicam (Zynrelef™) and more recently lidocaine liposome formulation. In these cases, the technology is used to prolong the duration of action of drugs included in the preparation. Another indication of nanotechnology is the development of nanocapacitor device or patches. Although, data obtained with the use of nanocapacitors are still limited, evidence suggests that the use of nanocapacitors devices/patches may be interesting for the treatment of both acute and chronic pain, since the studies conducted with the NeuroCuple™ device and the based Kailo™ pain relief patch were not placebo-controlled, it is clear that additional placebo studies are required to confirm these preliminary results. Therefore, the development of a placebo devices/patches is necessary. Conclusions: Increasing evidence supports the concept that nanotechnology may represent a valuable tool as a drug transporter including liposomes and as a nanocapacitor-based device/patch to reduce or even eliminate the use of opioids in surgical patients. However, more studies are required to confirm this concept, especially with the use of nanotechnology incorporated in devices/patches.

Safety and Efficacy of Zynrelef® in Combination with a Single Unilateral or Bilateral Nerve Block Performed Prior to Surgery

Purpose

The FDA recently approved Zynrelef® (A viscous solution of extended release of bupivacaine and meloxicam) to be applied at closure and providing postoperative analgesia for 72 hrs. Although the FDA didn't restrict the use of nerve blocks in combination with this formulation, the safety and efficacy of such a combination has yet to be documented. This quality improvement study investigated this combination within the FDA-approved indications.

Methods

Selected surgeons at two hospitals were chosen to use Zynrelef®. According to the standard of care, surgeons were also allowed to request single nerve blocks before surgery. The type of nerve blocks (unilateral or bilateral) performed included quadratus lumborum and paravertebral blocks for abdominal surgery, and adductor canal block for total knee replacement. Each block was performed with 20 mL of 0.375% bupivacaine (n=129) or 0.5% of ropivacaine (n=30). Pain scores, opioid consumption, and prescription refill requests at discharge were recorded. Patients discharged on the same day of surgery were separated into two groups-those who received single nerve blocks plus an Zynrelef® (group 1) vs. those receiving Zynrelef® only (group 2) and was analyzed using an un-paired t-test.

Results

A total of 184 patients received Zynrelef®, including 25 patients who didn't receive blocks, 44 who received unilateral blocks and 114 who received bilateral blocks. No symptoms suggestive of Local Anesthetic Toxicity (LAST) were observed. The use of the combination was associated with a 50% reduction in the number of patients filling their opioid prescription.

Conclusion

This study provides evidence that the combination of a single unilateral or bilateral nerve block with Zynrelef® is safe.

Comparison of Systemic Extended-release Buprenorphine and Local Extended-release Bupivacaine-Meloxicam as Analgesics for Laparotomy in Mice

Extended-release (ER) local anesthetics can be used in multi-modal analgesia or in situations in which systemic analgesics may alter animal physiology and thus introduce interpretational confounds. In this study, we compared the analgesic efficacy of an ER buprenorphine formulation with that of a synergistic combination of ER bupivacaine and meloxicam. Female and male CD1 mice were randomly assigned to receive subcutaneous buprenorphine (3.25mg/kg) preemptively, subcutaneous infiltration of bupivacaine???meloxicam (0.03mL at incision closure (bupivacaine, 35mg/kg; meloxicam, 1mg/kg), or saline (10mL/kg SC) after induction of anesthesia. After laparotomy, mice were assessed for changes in daily body weight, rearing frequency, nest consolidation scores, time-to-integrate-nest test (TINT), and response to von Frey testing at 4, 8, 24, 48, and 72h after surgery. Daily weight, nest consolidation scores and rearing frequency were not significantly different among the 3 groups. TINT had fallen significantly response at 24 and 48h after injection in the ER buprenorphine group as compared with the saline and ER bupivacaine-meloxicam groups. Nociceptive thresholds, as assessed with von Frey testing, differed between saline controls and both analgesic groups at 4, 8, 24, 48, and 72 h after surgery. None of the mice in the bupivacaine???meloxicam group developed signs of neurotoxicity, a potential side effect of high-dose local anesthetics. This study demonstrates that local ER bupivacaine???meloxicam may be a useful alternative to systemic, ER buprenorphine for the relief of pain after laparotomy in mice.

Peripheral Regional Anesthesia Using Local Anesthetics: Old Wine in New Bottles?

During the past decade, numerous efforts were undertaken aiming at prolonging the analgesic effect of regional anesthesia. With the development of extended-release formulations and enhanced selectivity for nociceptive sensory neurons, a very promising contribution to the development of pain medications has been achieved. At present, liposomal bupivacaine is the most popular, non-opioid, controlled drug delivery system, but its duration of action, which is still controversially discussed, and its expensiveness have decreased initial enthusiasm. Continuous techniques can be seen as an elegant alternative for providing a prolonged duration of analgesia, but for logistic or anatomical reasons, they are not always the best choice. Therefore, focus has been directed towards the perineural and/or intravenous addition of old and established substances. As for perineural application, most of these so-called 'adjuvants' are used outside their indication, and their pharmacological efficacy is often not or only poorly understood. This review aims to summarize the recent developments for prolonging the duration of regional anesthesia. It will also discuss the potential harmful interactions and side effects of frequently used analgesic mixtures.

Extended Release of Bupivacaine from Temperature-responsive Hydrogels Provides Multi-day Analgesia for Postoperative Pain

OBJECTIVE

A local anesthetic that provides analgesia lasting at least three days could significantly improve postoperative pain management. This study evaluated the analgesic efficacy and safety of an extended-release formulation of bupivacaine based on the injectable hydrogel carrier poly(N-isopropylacrylamide-co-dimethylbutyrolactone acrylamide-co-Jeffamine M-1000 acrylamide) (PNDJ).

METHODS

The efficacy of PNDJ containing 4% bupivacaine (SBG004) given by peri-incisional subcutaneous injection (SBG004 SC) or wound filling instillation (SBG004 WF) was evaluated compared to saline, liposomal bupivacaine, bupivacaine collagen sponge, bupivacaine-meloxicam polyorthoester, and bupivacaine HCl in a porcine skin and muscle incision model. Mechanical allodynia was assessed by withdrawal from application of von Frey filaments, and local tolerance was evaluated by histology. Bupivacaine pharmacokinetics for SBG004 SC were measured in rabbits (16.5 mg bupivacaine/kg).

RESULTS

Animals demonstrated less mechanical allodynia at incisions receiving SBG004 SC for up to 96 hours postoperatively. Incisions treated with SBG004 SC tolerated more force without a withdrawal indicative of pain compared to saline for 96 hours, and compared to SBG004 WF and all active controls at 24, 48, and 72 hours except bupivacaine-meloxicam polyorthoester at 72 hours. By 49 days, SBG004 was histologically absent and was replaced with granulation tissue infiltrated with immune cells in some areas. In rabbits, Cmax was 41.6 ± 9.7 ng/mL with t1/2 82.0 ± 35.8 hours (mean ± SD).

CONCLUSIONS

Peri-incisional SBG004 SC provided extended release of bupivacaine sufficient to reduce sensation of incisional pain for 96 hours, in vivo bupivacaine delivery for at least 7 days, and a favorable local and systemic toxicity profile.

Bupivacaine/meloxicam ER: A New Dual-acting Extended-Release Local Anesthetic for Opioid-Sparing Postoperative Pain Management

OBJECTIVE

To review data for bupivacaine/meloxicam extended-release (ER) solution for management of postoperative pain and opioid-sparing effects.

DATA SOURCES

Literature search of PubMed (1946 to August 2021) and ProQuest (1946 to August 2021) was performed using the terms: Zynrelef, HTX-011, and "bupivacaine AND meloxicam." Additional information sources include ClinicalTrials.gov, prescribing information, Heron Therapeutics' Clinical and Economic Evidence Dossier, meeting abstracts, and references of identified articles.

STUDY SELECTION AND DATA EXTRACTION

Clinical trials and articles evaluating bupivacaine/meloxicam ER for postoperative pain management.

DATA SYNTHESIS

Bupivacaine is a short-acting local anesthetic. Its efficacy is negatively impacted by the acidic environment of surgical sites. Meloxicam, a nonsteroidal antiinflammatory, reduces inflammation at the surgical site and increases pH propagating bupivacaine movement into the neurons. In Phase 2 and Phase 3 clinical trials, bupivacaine/meloxicam ER was compared with bupivacaine HCl, bupivacaine ER, and meloxicam ER with and without scheduled nonopioid multimodal analgesia (MMA) in bunionectomies, herniorrhaphies, total knee arthroplasty and abdominoplasty. Postoperative pain was well controlled for 72 hours and consistently superior to placebo, with minimal or no opioid use. Wound healing was not impacted and adverse effects were similar to placebo (most commonly nausea, dizziness, constipation, and headaches).

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

Bupivacaine/meloxicam ER is a viable, safe, nonopioid local anesthetic for sustained 72-hour postoperative pain management mitigating opioid consumption.

CONCLUSION

Bupivacaine/meloxicam ER is the only dual-acting, extended-release local anesthetic available. It provides effective analgesia in the postoperative setting and successfully reduces or eliminates postoperative opioid consumption.

A novel long-acting local anesthetic - HTX-011 (ZYNRELEF™) for postoperative pain control

INTRODUCTION

Pain following most surgical procedures is expected. However, the treatment and management of postoperative surgical pain has remained challenging. The use of opioid therapy has increasingly become controversial given the limited therapeutic window of these drugs, the adverse side effects, and the potential for abuse. A multimodal approach to the treatment of postoperative pain has been shown to improve pain outcomes after surgery and improve patient satisfaction. Here, we examine a new formulation of bupivacaine and meloxicam extended-release solution HTX-011 (Zenrelef®), and its efficacy in postoperative pain control.

AREAS COVERED

HTX-011 exists as an extended-release polymer that controls the release of the active ingredients over 72 hours. A systematic approach was taken to review PubMed (Medline) for prospective and retrospective studies related to the use of HTX-011 for the management of postoperative pain.

EXPERT OPINION

HTX-011 represents a new tool to help modulate postoperative pain. Although multimodal analgesia has been effective in managing postoperative pain, direct surgical infiltration with local anesthetics has had limited efficacy due to their short duration of action. The HTX-011 formulation provides a long-acting local anesthetic at the surgical site which provides a longer period of analgesia while maintaining a favorable safety profile.

Robust gelatin hydrogels for local sustained release of bupivacaine following spinal surgery

Adequate treatment of pain arising from spinal surgery is a major clinical challenge. Opioids are the mainstay of current treatment methods, but the frequency and severity of their side effects display a clear need for opioid-free analgesia. Local anesthetics have been encapsulated into sustained-release drug delivery systems to provide postoperative pain relief. However, these formulations are limited by rapid diffusion out of the surgical site. To overcome this limitation, we synthesized ring-shaped hydrogels incorporating bupivacaine, designed to be co-implanted with pedicle screws during spinal surgery. Hydrogels were prepared by riboflavin-mediated crosslinking of gelatin functionalized with tyramine moieties. Additionally, oxidized β-cyclodextrin was introduced into the hydrogel formulation to form dynamic bonds with tyramine functionalities, which enables self-healing behavior and resistance to shear. Feasibility of hydrogel implantation combined with pedicle screws was qualitatively assessed in cadaveric sheep as a model for instrumented spinal surgery. The in-situ crystallization of bupivacaine within the hydrogel matrix provided a moderate burst decrease and sustained release that exceeded 72 hours in vitro. The use of bupivacaine crystals decreased drug-induced cytotoxicity in vitro compared to bupivacaine HCl. Thus, the presented robust hydrogel formulation provides promising properties to enable the stationary release of non-opioid analgesics following spinal surgery. STATEMENT OF SIGNIFICANCE: Currently, postoperative pain following spinal surgery is mainly treated with opioids. However, the use of opioids is associated with several side effects including addiction. Here we developed robust and cytocompatible gelatin hydrogels, prepared via riboflavin-mediated photocrosslinking, that can withstand orthopedic implantation. The implantability was confirmed in cadaveric instrumented spinal surgery. Further, hydrogels were loaded with bupivacaine crystals to provide sustained release beyond 72 hours in vitro. The use of crystallized bupivacaine decreased cytotoxicity compared to bupivacaine HCl. The present formulation can aid in enabling opioid-free analgesia following instrumented spinal surgery.

HTX-011 in Combination with Multimodal Analgesic Regimen Minimized Severe Pain and Opioid Use after Total Knee Arthroplasty in an Open-Label Study

Total knee arthroplasty (TKA) can be associated with significant postoperative pain despite multimodal analgesic (MMA) protocols, and most patients require the use of opioids postoperatively. HTX-011 is a dual-acting local anesthetic containing bupivacaine and low-dose meloxicam in an extended-release polymer. In a prior randomized controlled trial (RCT), HTX-011 reduced pain and opioid use through 72 hours after TKA compared with bupivacaine hydrochloride. This open-label study (NCT03974932) evaluated the efficacy and safety of HTX-011 combined with an MMA regimen in patients undergoing TKA under spinal anesthesia. All patients received intraoperative HTX-011 (400 mg bupivacaine/12 mg meloxicam) in combination with an MMA regimen consisting of preoperative acetaminophen, celecoxib, and pregabalin and postoperative acetaminophen and celecoxib until discharge. Opioid rescue was allowed upon patient request for additional pain control. Pain scores, opioid consumption, discharge readiness, and adverse events were recorded. Fifty-one patients were treated. Compared with the prior RCT, HTX-011 with this MMA regimen further lowered pain scores and reduced opioid use. Mean patient-reported pain scores remained in the mild range, and 82% of patients or more did not experience severe pain at any individual time point through 72 hours after surgery. Mean total opioid consumption was low over 72 hours: 24.8 morphine milligram equivalents (1-2 tablets of oxycodone 10 mg/day). Approximately 60% of patients were ready for discharge by 12 hours, and 39% were discharged without an opioid prescription and did not call back for pain management. The treatment regimen was well tolerated, and no added risk was observed with the addition of MMA. HTX-011 with an MMA regimen reduced postoperative pain and opioid use following TKA.

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

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

Comparison of in vitro and in vivo Toxicity of Bupivacaine in Musculoskeletal Applications

The recent societal debate on opioid use in treating postoperative pain has sparked the development of long-acting, opioid-free analgesic alternatives, often using the amino-amide local anesthetic bupivacaine as active pharmaceutical ingredient. A potential application is musculoskeletal surgeries, as these interventions rank amongst the most painful overall. Current literature showed that bupivacaine induced dose-dependent myo-, chondro-, and neurotoxicity, as well as delayed osteogenesis and disturbed wound healing in vitro. These observations did not translate to animal and clinical research, where toxic phenomena were seldom reported. An exception was bupivacaine-induced chondrotoxicity, which can mainly occur during continuous joint infusion. To decrease opioid consumption and provide sustained pain relief following musculoskeletal surgery, new strategies incorporating high concentrations of bupivacaine in drug delivery carriers are currently being developed. Local toxicity of these high concentrations is an area of further research. This review appraises relevant in vitro, animal and clinical studies on musculoskeletal local toxicity of bupivacaine.

Novel Local Anesthetics in Clinical Practice: Pharmacologic Considerations and Potential Roles for the Future

The treatment of pain, both acute and chronic, has been a focus of medicine for generations. Physicians have tried to develop novel ways to effectively manage pain in surgical and post-surgical settings. One intervention demonstrating efficacy is nerve blocks. Single-injection peripheral nerve blocks (PNBs) are usually preferred over continuous PNBs, since they are not associated with longer lengths of stay. The challenge of single injection PNBs is their length of duration, which at present is a major limitation. Novel preparations of local anesthetics have also been studied, and these new preparations could allow for extended duration of action of anesthetics. An emerging preparation of bupivacaine, exparel, uses a multivesicular liposomal delivery system which releases medication in a steady, controlled manner. Another extended-release local anesthetic, HTX-011, consists of a combination of bupivacaine and low-dose meloxicam. Tetrodotoxin, a naturally occurring reversible site 1 sodium channel toxin derived from pufferfish and shellfish, has shown the potential to block conduction of isolated nerves. Neosaxitoxin is a more potent reversible site 1 sodium channel toxin also found in shellfish that can also block nerve conduction. These novel formulations show great promise in terms of the ability to prolong the duration of single injection PNBs. This field is still currently in development, and more researchers will need to be done to ensure the efficacy and safety of these novel formulations. These formulations could be the future of pain management if ongoing research continues to prove positive effects and low side effect profiles.

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

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

Opioid-Free Recovery After Hernia Repair with HTX-011 as the Foundation of a Non-Opioid, Multimodal Analgesia Regimen in a Real-World Setting: A Randomized, Open-Label Study

INTRODUCTION

Helping Opioid Prescription Elimination (HOPE) is a project designed to provide surgeons with practical, real-world solutions to effectively manage postoperative pain and eliminate the need for opioids using HTX-011 (extended-release bupivacaine/low-dose meloxicam). In phase 3 herniorrhaphy and bunionectomy studies, HTX-011 without multimodal analgesia (MMA) was superior to bupivacaine hydrochloride in reducing pain and opioid consumption. Here, we examine the HOPE Hernia-1 study, which was designed to compare alternating ibuprofen/acetaminophen with concurrent use as part of an HTX-011-based non-opioid MMA regimen in patients undergoing herniorrhaphy and to evaluate the effectiveness of a personalized opioid prescription algorithm.

METHODS

Patients undergoing outpatient open inguinal herniorrhaphy with intraoperative administration of HTX-011 (300 mg bupivacaine/9 mg meloxicam) were randomly assigned to receive a scheduled oral regimen of ibuprofen plus acetaminophen, either taken together every 6 hours or alternating every 3 hours, for 5 days following surgery, while awake. Based on the opioid prescription algorithm evaluated here, patients could receive an oxycodone prescription upon discharge only if they had a numeric rating scale pain score of ≥ 6 at discharge and/or had received a postoperative rescue opioid.

RESULTS

The majority of patients did not require an opioid prescription through 2 weeks following surgery, and this was similar between cohorts (alternating MMA, 89.1%; concurrent MMA, 93.6%). Patient satisfaction was high for both regimens, and 95% of patients had an opioid-free recovery. No patient discharged without a prescription called back to request one. Treatment was well tolerated, without evidence of nonsteroidal anti-inflammatory drug-related toxicity.

CONCLUSIONS

HTX-011, used with over-the-counter products ibuprofen/acetaminophen and personalized opioid prescription algorithm in a real-world environment, has the potential to reduce opioid use and opioid prescriptions after herniorrhaphy without compromising patient satisfaction.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03237481.

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.

Emerging drugs for the treatment of postsurgical pain

INTRODUCTION

Postoperative pain is a distressful experience and remains to be a significant concern after surgery. Current agents either fail to prevent or minimize postoperative pain or cause a series of adverse effects, addiction, or abuse. Opioids have been the gold standard in the treatment of postoperative pain despite their well-described adverse effects. Many new agents with different mechanisms of action have been recently introduced to address this issue.

AREAS COVERED

This current review summarizes the list of new and emerging drugs investigated for their efficacy in controlling the postoperative pain and decreasing the need for rescue opioid use, adverse effect profile, abuse, and addiction potential.

EXPERT OPINION

Opioids have unrivaled analgesic efficacy. However adverse effects of opioids led to the search for better options. In mild pain most of the emerging drugs have been shown to control postoperative pain and decrease the use of rescue opioid, however fail to control pain after major surgeries causing severe pain. Specific agents such as Oliceridine, new local anesthetics, etc., are effective in controlling severe pain and hold a promise to replace opioids in the near future.

A systematic review of porcine models in translational pain research

Translating basic pain research from rodents to humans has proven to be a challenging task. Efforts have been made to develop preclinical large animal models of pain, such as the pig. However, no consistent overview and comparison of pig models of pain are currently available. Therefore, in this review, our primary aim was to identify the available pig models in pain research and compare these models in terms of intensity and duration. First, we systematically searched Proquest, Scopus and Web of Science and compared the duration for which the pigs were significantly sensitized as well as the intensity of mechanical sensitization. We searched models within the specific field of pain and adjacent fields in which pain induction or assessment is relevant, such as pig production. Second, we compared assessment methodologies in surrogate pain models in humans and pigs to identify areas of overlap and possible improvement. Based on the literature search, 23 types of porcine pain models were identified; 13 of which could be compared quantitatively. The induced sensitization lasted from hours to months and intensities ranged from insignificant to the maximum attainable. We also found a near to complete overlap of assessment methodologies between human and pig models within the area of peripheral neurophysiology, which allows for direct comparison of results obtained in the two species. In spite of this overlap, further development of pain assessment methodologies is still needed. We suggest that central nervous system electrophysiology, such as electroencephalography, electrocorticography or intracortical recordings, may pave the way for future objective pain assessment.

HTX-011 effectively reduces postoperative pain intensity and opioid use in the elderly

Aim: HTX-011 (ZYNRELEF™) is an extended-release, dual-acting local anesthetic containing bupivacaine and meloxicam. In bunionectomy and herniorrhaphy studies, HTX-011 resulted in less postoperative pain and less opioid consumption versus bupivacaine HCl. Here we evaluate HTX-011 in patients aged ≥65 years. Materials & methods: Patients received placebo, bupivacaine HCl or HTX-011 following surgery. End points included pain intensity, total opioid consumption, opioid-free patients and safety. Results: HTX-011-treated patients reported lower postoperative pain through 72 h versus bupivacaine HCl and placebo. Elderly patients administered HTX-011 used fewer opioids versus bupivacaine HCl, and a greater proportion remained opioid-free through 72 h. HTX-011 was well tolerated with a safety profile similar to bupivacaine HCl and placebo. Conclusion: HTX-011 maintained effectiveness and was well tolerated in elderly patients. Clinical Trial Registration: NCT03295721 and NCT03237481.

Bupivacaine/Meloxicam Prolonged Release: A Review in Postoperative Pain

Prolonged-release (PR; as ascribed in the EU) or extended-release (as ascribed in the USA) bupivacaine/meloxicam (HTX-011; hereafter referred to as bupivacaine/meloxicam PR; Zynrelef^®) is a synergistic fixed-dose combination (FDC) of the local anaesthetic bupivacaine and the NSAID meloxicam. It is approved in the EU and the USA to treat postoperative pain. After needle-free application at the surgical site, the novel polymer technology allows simultaneous diffusion of bupivacaine and meloxicam over 72 h. In clinical trials, bupivacaine/meloxicam PR significantly reduced postoperative pain and opioid consumption relative to bupivacaine hydrochloride (HCl) and placebo in patients undergoing bunionectomy, herniorrhaphy or total knee arthroplasty (TKA). When used as the foundation of a scheduled non-opioid multimodal analgesia (MMA) regimen, bupivacaine/meloxicam PR further improved pain control and reduced the need for opioids following surgery. Bupivacaine/meloxicam PR was generally well tolerated, with a lower incidence of opioid-related adverse events than bupivacaine HCl and placebo. Although additional data would be beneficial, current evidence indicates that bupivacaine/meloxicam PR is a promising non-opioid treatment option for the management of postoperative pain.

Opioid-Free Recovery from Bunionectomy with HTX-011, a Dual-Acting Local Anesthetic Combining Bupivacaine and Meloxicam, as the Foundation of Non-Opioid Multimodal Analgesia

BACKGROUND

There is a need for postoperative pain control that minimizes or eliminates opioid use during the first 72 hours following surgery, when pain is most severe. HTX-011 is an extended-release, dual-acting local anesthetic that demonstrated superior 72-hour analgesia over standard of care bupivacaine hydrochloride (HCl) and saline placebo in a phase 3 bunionectomy study (EPOCH-1). Having shown HTX-011 monotherapy is superior to bupivacaine HCl in reducing postoperative pain intensity and opioid use, this follow-on study evaluated the safety and efficacy of HTX-011 as the foundation of a multimodal analgesia (MMA) regimen using over-the-counter medications recommended by practice guidelines for pain management.

METHODS

Following regional anesthesia administered as a lidocaine block, patients underwent unilateral bunionectomy with osteotomy and internal fixation. Prior to closure, HTX-011 (up to 60 mg bupivacaine/1.8 mg meloxicam) was applied without a needle. Patients received scheduled postoperative MMA alternating ibuprofen (600 mg) and acetaminophen (1 g) every 3 hours for 72 hours. Efficacy was assessed based on pain intensity (numeric rating scale [NRS; 0-10]) and consumption of opioid rescue medication (intravenous morphine milligram equivalents [MME]). Adverse event and vital sign monitoring, plus laboratory and wound healing assessments, were used to determine safety.

RESULTS

Over the 72-hour assessment period following bunionectomy, mean pain scores were mild in severity (NRS <4) and 22/31 patients (71%) experienced no severe pain (NRS ≥7) with HTX-011 as the foundation of scheduled, non-opioid MMA. Patients consumed an average of 1.61 MME total, with 24/31 (77%) requiring no opioid rescue medication (opioid-free). HTX-011 was well-tolerated and demonstrated no safety concerns with the inclusion of postoperative MMA.

CONCLUSIONS

HTX-011 as the foundation of an MMA regimen including scheduled ibuprofen and acetaminophen maintained mean postoperative pain scores in the mild range and enabled opioid-free recovery for 77% of bunionectomy patients through the 28-day recovery period.

Nanotherapeutic-directed approaches to analgesia

The ongoing opioid crisis highlighted the need for non-steroidal anti-inflammatory drugs (NSAIDs), nonaddictive analgesics against pain, fever, and inflammation. However, NSAIDs may cause gastrointestinal and cardiovascular adverse effects. To avoid systemic toxicity and deliver drugs to diseased tissues, nanotechnology methods of NSAID encapsulation have been reported and some have reached clinical development. Currently, 57 micro- and nanodrugs are approved by the US FDA. Already approved nanoanalgesics have revealed superior efficacy or reduced toxicity compared with placebo or lower doses of systemically administered active comparators. In this review, the evidence for approval of the marketed nanodrugs will be discussed, with a focus on therapies for pain and inflammation. Nanomedicine remains an attractive field for the development of targeted analgesics.

HTX-011 (bupivacaine and meloxicam) for the prevention of postoperative pain - clinical considerations

HTX-011 is an extended-release, dual-acting local anesthetic consisting of bupivacaine (sodium-channel blocker) and low-dose meloxicam (non-steroidal anti-inflammatory drug [NSAID]) applied needle-free during surgery. Introducing low-dose meloxicam addresses the limited efficacy of liposomal bupivacaine in acidic inflamed tissues and allows enhanced analgesic effects over three days. It has great promise to be an extremely effective postoperative pain regimen and produce an opioid-free surgical recovery, as it has consistently significantly reduced pain scores and opioid consumption through 72 h. This manuscript provides an updated, concise narrative review of the pharmacology, clinical efficacy, safety and tolerability of this drug and its applications to prevent postoperative pain.

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.

Entrapping bupivacaine-loaded emulsions in a crosslinked-hydrogel increases anesthetic effect and duration in a rat sciatic nerve block model

The purpose of this research was to evaluate a novel long-acting bupivacaine delivery system for control of postoperative pain. Bupivacaine-loaded lipid emulsion (BLE) droplets were created by high-speed homogenization. The BLE droplets were then entrapped into a crosslinked-hyaluronic acid hydrogel system to create an injectable composite gel formulation (HA-BLE). Dynamic light scattering, rheological, and drug release techniques were used to characterize the formulations. A rat sciatic nerve block with a thermal nociceptive assay was used to evaluate the anesthetic effect in comparison to controls, bupivacaine HCl and liposomal bupivacaine. The BLE droplets had a zeta potential, droplet size, and polydispersity index of -40.8 ± 0.66 mV, 299 ± 1.77 nm, and 0.409 ± 0.037, respectively. The HA-BLE formulation could be injected through 25 g needles and had an elastic modulus of 372 ± 23.7 Pa. Approximately 80% and 100% of bupivacaine was released from the BLE and HA-BLE formulations by 20 and 68 h, respectively. The HA-BLE formulation had a 5-times greater anesthetic area under the curve and an anesthetic duration that was twice as long as controls. Results indicate that incorporating the BLEs into the hydrogel significantly increased anesthetic effect by protecting the BLE droplets from the in vivo environment.

HTX-011 Reduced Pain and Opioid Use After Primary Total Knee Arthroplasty: Results of a Randomized Phase 2b Trial

BACKGROUND

HTX-011 is an extended-release, dual-acting local anesthetic consisting of bupivacaine and low-dose meloxicam in a novel polymer that is administered by needle-free application during surgery. The active ingredients are released from the polymer by controlled diffusion over 72 hours.

METHODS

This phase 2b, double-blind, placebo-controlled and active-controlled trial enrolled patients undergoing primary unilateral total knee arthroplasty under general anesthesia. Two hundred thirty-two patients were randomized into 4 groups: HTX-011 400 mg bupivacaine/12 mg meloxicam, applied without a needle into the surgical site, the same dose of HTX-011 with a separate 50 mg ropivacaine injection into the posterior capsule, bupivacaine hydrochloride (HCl) 125 mg injection, and saline placebo injection. Only opioids were permitted for postoperative pain rescue. Primary and key secondary endpoints were mean area under the curve of pain intensity scores over 48 hours and 72 hours, respectively, for HTX-011 groups vs placebo.

RESULTS

Both HTX-011 groups had significantly reduced mean pain intensity vs placebo through 48 and 72 hours (both P < .001). Ropivacaine added a small initial benefit in the first 12 hours. Both HTX-011 groups also had decreased mean pain intensity vs bupivacaine HCl alone through 48 and 72 hours (P < .05). The HTX-011 groups had significantly earlier discharge readiness along with lower opioid consumption through 72 hours. HTX-011 alone or with ropivacaine was well-tolerated with a safety profile similar to controls.

CONCLUSION

Needle-free application of HTX-011 400 mg bupivacaine/12 mg meloxicam provided superior pain reduction through 72 hours after total knee arthroplasty compared with placebo and bupivacaine HCl alone.