Evaluating the influence of particle morphology and density on the viscosity and injectability of a novel long-acting local anesthetic suspension.

Proper pain management is well understood to be one of the fundamental aspects of a healthy postoperative recovery in conjunction with mobility and nutrition. Approximately, 10% of patients prescribed opioids after surgery continue to use opioids in the long-term and as little as 10 days on opioids can result in addiction. In an effort to provide physicians with an alternative pain management technique, this work evaluates the material properties of a novel local anesthetic delivery system designed for controlled release of bupivacaine for 72 hours. The formulation utilizes solid-lipid microparticles that encapsulate the hydrophobic molecule bupivacaine in its free-base form. The lipid microparticles are suspended in a non-crosslinked hyaluronic acid hydrogel, which acts as the microparticle carrier. Two different particle manufacturing techniques, milling and hot homogenization, were evaluated in this work. The hot homogenized particles had a slower and more controlled release than the milled particles. Rheological techniques revealed that the suspension remains a viscoelastic fluid when loaded with either particle type up to 25% (w/v) particles densities. Furthermore, the shear thinning properties of the suspension media, hyaluronic acid hydrogel, were conserved when bupivacaine-loaded solid-lipid microparticles were loaded up to densities of 25% (w/v) particle loading. The force during injection was measured for suspension formulations with varying hyaluronic acid hydrogel concentrations, particle densities, particle types and particle sizes. The results indicate that the formulation viscosity is highly dependent on particle density, but hyaluronic acid hydrogel is required for lowering injection forces as well as minimizing clogging events.

Determination of bupivacaine tissue concentration in human biopsy samples using high-performance liquid chromatography with mass spectrometry.

In the present study, we developed a simple and rapid analytical method for the quantification of bupivacaine hydrochloride in human biopsy samples of adipose, muscle, neural, connective and cartilage tissue using liquid chromatography-mass spectrometry. Anesthetics were extracted from the tissue samples using 0.1% formic acid in acetonitrile for protein denaturation and hexane for removal of lipophilic impurities. Analytes were separated adequately on Phenomenex Luna Omega polar C18 column using a gradient mobile phase 0.1% formic acid in water and 0.1% formic acid in acetonitrile. The lower limits of quantification were ≤ 97 ng g-1 tissue for all studied tissues. Intra-day recoveries were between 48.2% and 82.1% with relative standard deviations (RSDs) between 1.47% and 14.28%, whereas inter-day recoveries were between 52.2% and 77.6% with RSDs between 2.98% and 14.79%. The calibration curve showed a linear fit with R2 higher than 0.99 in the concentration range from 0.16 to 100 µg g-1 . Lidocaine hydrochloride was tested as internal standard because its recoveries and matrix effects were comparable to bupivacaine hydrochloride. Post-analytical corrections of measured bupivacaine tissue concentrations can accordingly be made based on recovery of lidocaine as internal standard, with recoveries between 51.2% and 86.9% and RSDs between 1.99% and 16.88%. The developed method could be used to study time-dependent spread of bupivacaine locally or to more distant locations across tissue barriers.

A prospective randomized trial comparing liposomal bupivacaine vs standard bupivacaine wound infiltration in open gynecologic surgery on an enhanced recovery pathway.

BACKGROUND: Value in healthcare is reflected by patient-centered outcomes of care per health dollar expended. Although liposomal bupivacaine is more expensive, it has been shown to provide prolonged analgesia (up to 72 hours). OBJECTIVE: This study aimed to evaluate whether the addition of liposomal bupivacaine to standard bupivacaine could decrease opioid intake and improve pain control after laparotomy for gynecologic surgery compared with standard bupivacaine alone in an enhanced recovery after surgery pathway. STUDY DESIGN: A prospective randomized controlled single-blinded trial of wound infiltration with liposomal bupivacaine plus 0.25% bupivacaine (study arm) vs 0.25% bupivacaine (control arm) was performed at a National Cancer Institute-designated tertiary referral cancer center. Participants were patients aged ≥18 years undergoing exploratory laparotomy for a gynecologic indication. All patients were treated on an enhanced recovery pathway including local wound infiltration before closure. In this study, 266 mg of liposomal bupivacaine (free base; equal to 300 mg bupivacaine HCL)+150 mg of bupivacaine mixed in the same syringe was used in the study arm, and 150 mg of bupivacaine was used in the control arm. The primary outcome was the proportion of patients who were opioid-free within 48 hours after surgery. Secondary outcomes included number of opioid-free days from postoperative day 0 to postoperative day 3, days to first opioid administration, morphine equivalent daily dose, and patient-reported outcomes collected with the MD Anderson Symptom Inventory. The MD Anderson Symptom Inventory was administered as a preoperative baseline, daily while hospitalized, and at least weekly for 8 weeks after discharge. All outcomes were prespecified before data collection. RESULTS: In this study, 102 patients were evaluated. Among them, 16.7% of patients in the study arm received no opioids up to 48 hours compared with 14.8% in the control arm (P=.99). There were no significant differences in the amount of intraoperative opioids administered or days to first opioid use. There was no significant difference between the 2 arms in median cumulative morphine equivalent daily dose (21.3 [study arm] vs 33.8 [control arm]; P=.36) or between the groups in morphine equivalent daily dose per individual day. There were no significant differences in patient-reported pain or interference with walking between the 2 arms or other patient-reported outcomes. CONCLUSION: Within an enhanced recovery after surgery pathway, adding liposomal bupivacaine to 0.25% bupivacaine wound infiltration did not decrease the proportion of patients who were opioid-free within 48 hours after surgery, did not decrease opioid intake, or did not improve patient's self-reported pain and functional recovery compared with standard bupivacaine.

Studying the effect of vasopressors on therapeutic drug monitoring of two local anesthetics using hybrid micelle liquid chromatography as an analysis tool.

A hybrid micelle based mobile phase was used to develop and validate a liquid chromatographic method for the separation and quantification of two local anesthetics namely; lidocaine hydrochloride (LID), and bupivacaine hydrochloride (BPV) in presence of the frequently co administered vasopressors phenyl ephrine (PHR) and ephedrine (EPH). Optimization of chromatographic separation conditions was performed applying experimental one factor at a time tool, and design of experiment, where the retention behavior of all analytes using both optimization protocols was in accordance. Chromatographic separation was carried on a C8 column operating at 40 °C at a flow rate of 1.5 mL/min. using a mobile phase consisting of 0.18 M sodium dodecyl sulphate, 10% acetonitrile, containing 0.3% triethyl amine and adjusted to pH 7 using 2 M ortho phosphoric acid, adopting UV detection at 230 nm. The proposed method was fully validated and applied to both in vitro and in vivo analysis of rat blood samples. The pharmacokinetics of both LID and BPV was followed when they were solitary injected or when co administered with either PHR or EPH. Moreover, the in vitro spiked experiment was also subjected to documented bio-analytical validation procedures.

Transcutaneous anaesthetic nano-enabled hydrogels for eyelid surgery.

Local anaesthetics are administered as a diffuse superficial slow injection in blepharoplasty. Current transcutaneous local anaesthetic formulations are not licensed for use on the face due to safety concerns. Here we report for the first time the permeation of local anaesthetics (lidocaine, bupivacaine loaded SNEDDS and their hydrogels) across human eyelid and mouse skin as a novel and ocular safe formulation for eyelid surgery. SNEDDS were loaded with high levels of anaesthetics and incorporated within carbomer hydrogels to yield nano-enabled gels. Lidocaine hydrogels have a significantly reduced lag time compared to EMLA, while they enhance lidocaine flux across human eyelid skin by 5.2 fold. Ex vivo tape stripping experiments indicated localisation of anaesthetics within the stratum corneum and dermis. Initial histopathological studies have shown no apparent signs of skin irritation. These results highlight the potential clinical capability of nano-enabled anaesthetic hydrogels as a non-invasive anaesthetic procedure for eyelid surgery.

Citrem-phosphatidylcholine nano-self-assemblies: solubilization of bupivacaine and its role in triggering a colloidal transition from vesicles to cubosomes and hexosomes.

Improvement of pain management strategies after arthroscopic surgery by multimodal analgesia may include the use of long-acting amide local anesthetics. Among these anesthetics, the low molecular weight local anesthetic agent bupivacaine (BUP) is attractive for use in postoperative pain management. However, it has a relatively short duration of action and imposes a higher risk of systemic toxicity at relatively large bolus doses. Bupivacaine encapsulation in lipid-based delivery systems is an attractive strategy for prolonging its local anaesthetic effect and reducing the associated undesirable systemic side effects. Here, we discuss the potential development of liquid crystalline nanocarriers for delivering BUP by using a binary lipid mixture of citrem and soy phosphatidylcholine (SPC) at different weight ratios. The produced safe-by-design family of citrem/SPC nanoparticles is attractive for use in the development of nanocarriers owing to the previously reported hemocompatibility. BUP encapsulation efficiency (EE), depending on the lipid composition, was in the range of 65-77%. In this study, nanoparticle tracking analysis (NTA) and synchrotron small-angle X-ray scattering (SAXS) were employed to gain insight into the effect of BUP solubilization and lipid composition on the size and structural characteristics of the produced citrem/SPC nanodispersions. BUP loading led to a slight change in the mean sizes (diameters) and size distributions of citrem/SPC nanoparticles. However, we found that BUP accommodation into the self-assembled interiors of nanoparticles, triggers significant structural alterations in BUP concentration- and lipid composition-dependent manners, which involve vesicle-cubosome and vesicle-hexosome transitions. The structural tunability of citrem/SPC nanoparticles and the implications for potential applications in intra-articular BUP delivery are discussed.

Delivery of bupivacaine from UHMWPE and its implications for managing pain after joint arthroplasty.

Total joint replacement is a widely used and successful surgical approach. Approximately 7 million US adults are currently living with a hip or knee replacement. However, the surgical procedures for total joint replacement are associated with significant postoperative pain, and current strategies do not adequately address this pain, which leads to patient dissatisfaction, reduced mobility, and increased risk of opioid addiction. We hypothesized that the ultra-high-molecular-weight polyethylene (UHMWPE) bearing surfaces used in total joint prosthetics could provide sustained release of the local anesthetic bupivacaine to provide relief from joint pain for an extended period of time after surgery. In this paper, we describe the production of bupivacaine-loaded UHMWPE (BPE) and measure the in vitro bupivacaine release kinetics of BPE. We found that bupivacaine could be released from BPE at clinically relevant rates for up to several days and that BPE possesses antibacterial effects. Therefore, bupivacaine-loaded UHMWPE is a promising material for joint replacement prostheses, and future studies will evaluate its safety and efficacy in in vivo models. STATEMENT OF SIGNIFICANCE: Total joint replacement is associated with significant pain and risk of infection. In our paper, we introduce bupivacaine-loaded ultra-high-molecular-weight polyethylene (BPE), which releases bupivacaine, a pain-treating drug, at doses comparable to currently used doses. Additionally, BPE inhibits the growth of infection-causing bacteria. Therefore, BPE may be able to reduce both postsurgical pain and risk of infection, potentially treating two of the most prominent complications associated with total joint replacement. To our knowledge, this is the first development of a material that can address both complications, and devices incorporating BPE would represent a significant advancement in joint arthroplasty prosthetics. More generally, the incorporation of therapeutic agents into ultra-high-molecular-weight polyethylene could impact many orthopedic procedures owing to its ubiquity.

Pain control using liposomal bupivacaine versus bupivacaine for robotic assisted thoracic surgery.

Background Despite a trend towards minimally invasive thoracic surgeries over thoracotomies, patients can still experience significant post-operative pain. Literature on the use of liposomal bupivacaine in patients undergoing robotic surgeries is lacking. Objective To compare pain control via intercostal nerve block with liposomal bupivacaine to bupivacaine for patients undergoing robotic assisted thoracic surgery. Setting A 455 bed community hospital. Methods This was a prospective observational study with a historical control group of 96 patients who underwent robotic lung resection. Patients in the control group received bupivacaine, while the intervention group received liposomal bupivacaine. Main outcome measure Average pain scores 24, 48, and 72 h after surgery. Results There were no significant differences in average pain scores between groups. The frequency of ketorolac use on the first post-operative day was lower for those who received liposomal bupivacaine. There were no significant differences in opioid requirements, length of stay, or rate of complications. Conclusions There was no significant difference in post-operative pain control between patients receiving liposomal bupivacaine and bupivacaine for robotic assisted surgery.

Plasma and synovial fluid concentrations and cartilage toxicity of bupivacaine following intra-articular administration of a liposomal formulation to horses.

BACKGROUND: The use of intra-articular (IA) local anaesthetics has proven to be an effective means to treat post-operative pain. The effects of local anaesthetics on equine chondrocytes are mixed with some studies reporting chondrodestruction and others no adverse effects. A liposomal formulation of bupivacaine is used in people and dogs by intra- and peri-articular administration to provide up to 72 h of analgesia. The potential uses, side effects including chondrotoxicity, and likelihood of abuse (long-term analgesic effects) has not been evaluated in horses. OBJECTIVES: Describe bupivacaine concentrations following IA administration and assess biomarkers as indicators of the effects of liposomal bupivacaine on chondrocytes in vivo. STUDY DESIGN: Parallel design. METHODS: Sixteen exercised horses received a single IA administration of 0.12 mg/kg liposomal bupivacaine or 0.9% saline. Blood and urine samples were collected for 96 h post-drug administration. Six horses treated with bupivacaine and those receiving saline, underwent daily arthrocentesis. Six additional bupivacaine treated horses underwent arthrocentesis at 96 h. Drug concentrations were measured using LC-MS/MS and pharmacokinetic analyses performed. Immunoassays were used to measure markers of collagen degradation (C2C, C12C) and cartilage matrix synthesis (CPII, CS846) in synovial fluid. RESULTS: The bupivacaine plasma elimination half-life was 17.8 ± 5.42 and 11.9 ± 5.17 h for horses from which synovial fluid was collected daily and at 96 h respectively. Bupivacaine concentrations in the joint were still detectable at 96 h. Significant increases in C12C and C2C were noted at 96 h in horses undergoing arthrocentesis at 96 h only. CPII was increased at 48 h and CS846 at 24 and 48 h in horses sampled daily. MAIN LIMITATIONS: Limited number of animals and absence of liposome control group. CONCLUSIONS: Sustained concentrations of IA bupivacaine suggest viability of this medication as an intra-articular analgesic. Effects on equine chondrocytes need further study.

Long-acting hydrogel/microsphere composite sequentially releases dexmedetomidine and bupivacaine for prolonged synergistic analgesia.

Local anesthetics are a class of drugs, which have wide applications in the treatment of acute and chronic pain. However, their analgesic effects only last for a few hours because of their short half-life, which is insufficient for clinical application, especially for long-term surgery or postoperative analgesia. Herein, an injectable hydrogel/microsphere (GEL/MS) composite co-encapsulating bupivacaine (BUP) and dexmedetomidine (DEX) was developed for effective sustained analgesia. The GEL/MS composite appeared as a three-dimensional porous network microstructure and displayed sustained sequential release of DEX and BUP over several days in vitro, without obvious burst release. In this composite, DEX was released from the GEL matrix preferentially, exhibited long-term vasoconstriction effect and improved the local anesthetic concentration at injection site by preventing BUP from diffusing into the blood circulation. BUP was released subsequently from the MS for blockage of the Na+ channel on nerve cell membranes and provided long-term analgesia. In vivo analgesic effect demonstrated that DEX significantly prolonged the effect of analgesia when synergistically administered with BUP in the GEL/MS composite. Moreover, the GEL/MS composite exhibited good biodegradability and biocompatibility in histological analyses. Taken together, the administration of BUP and DEX in the GEL/MS composite achieved a synergistic effect in prolonging analgesia without causing toxicity, and thus represented a potential strategy for long-acting analgesia therapy.

Local sustained delivery of bupivacaine HCl from a new castor oil-based nanoemulsion system.

Bupivacaine HCl (1-butyl-2',6'-pipecoloxylidide hydrochloride), an amide local anesthetic compound, is a local anesthetic drug utilized for intraoperative local anesthesia, post-operative analgesia and in the treatment of chronic pain. However, its utility is limited by the relative short duration of analgesia after local administration (approximately 9 h after direct injection) and risk for side effects. This work is aimed to develop a nanoemulsion of bupivacaine HCl with sustained local anesthetics release kinetics for improved pain management, by exhibiting extended analgesic action and providing reduced peak levels in the circulation to minimize side effects. Herein, biodegradable oils were evaluated for use in nanoemulsions to enable sustained release kinetics of bupivacaine HCl. Only with castor oil, a clear and stable nanoemulsion was obtained without the occurrence of phase separation over a period of 3 months. High loading of bupivacaine HCl into the castor oil-based nanoemulsion system was achieved with about 98% entrapment efficiency and the resulting formulation showed high stability under stress conditions (accelerated stability test) regarding changes in visual appearance, drug content, and droplet size. We show herein that the in vitro release and in vivo pharmacokinetic profiles as well as pharmacodynamic outcome (pain relief test) after subcutaneous administration in rats correlate well and clearly demonstrate the prolonged release and extended duration of activity of our novel nanoformulation. In addition, the lower Cmax value achieved in the blood compartment suggests the possibility that the risk for systemic side effects is reduced. We conclude that castor oil-based nanomulsion represents an attractive pain treatment possibility to achieve prolonged local action of bupivacaine HCl.

Effect of oil structure on cyclodextrin-based Pickering emulsions for bupivacaine topical application.

Cyclodextrins (CDs) coupled with oils forms an insoluble inclusion complex that is able to adsorb to the interface between oils and aqueous phases; it thereby stabilizes Pickering emulsions. Three types of oils (triglyceride, linear chain oil, and ring-structured oil) were chosen to work with CDs to prepare bupivacaine (BPC)-encapsulated Pickering emulsions. We also investigated the relationship between oils and CDs; as well as their influences on stability, drug-releasing capability and skin permeability. Particle sizes and microstructures were determined by dynamic light scattering and scanning electron microscopy, respectively. In vitro drug release studies and in vitro skin permeation studies were evaluated by using Franz diffusion model. Particle sizes of all Pickering emulsions were larger than 1µm, and the morphology was spherical and covered with rough surfaces. BPC was released over an extended period, and the releasing ratios from Pickering emulsions were only 12.2%-23.1% after 48h. In skin permeation studies, compared with other formulations, a formula involved with ring-structured oil allowed the highest permeation amount through skin. However, after 24h of exposure, formulation operated with linear chain oil showed the highest skin-retaining amount. These results suggest that Pickering emulsions could regulate the target site of skin depending on various types of oil used.

Transversus Abdominis Plane Block: An Updated Review of Anatomy and Techniques.

PURPOSE OF REVIEW: Transversus abdominis plane (TAP) block is a regional technique for analgesia of the anterolateral abdominal wall. This review highlights the nomenclature system and recent advances in TAP block techniques and proposes directions for future research. RECENT FINDINGS: Ultrasound guidance is now considered the gold standard in TAP blocks. It is easy to acquire ultrasound images; it can be used in many surgeries involving the anterolateral abdominal wall. However, the efficacy of ultrasound-guided TAP blocks is not consistent, which might be due to the use of different approaches. The choice of technique influences the involved area and block duration. To investigate the actual analgesic effects of TAP blocks, we unified the nomenclature system and clarified the definition of each technique. Although a single-shot TAP block is limited in duration, it is still the candidate of the analgesic standard for abdominal wall surgery because the use of the catheter technique and liposomal bupivacaine may overcome this limitation. SUMMARY: Ultrasound-guided TAP blocks are commonly used. With the unified nomenclature and the development of catheter technique and/or liposomal local anesthetics, TAP blocks can be applied more appropriately to achieve better pain control.

Hyperbaric Versus Isobaric Bupivacaine for Spinal Anesthesia: Systematic Review and Meta-analysis for Adult Patients Undergoing Noncesarean Delivery Surgery.

BACKGROUND: It is widely believed that the choice between isobaric bupivacaine and hyperbaric bupivacaine formulations alters the block characteristics for the conduct of surgery under spinal anesthesia. The aim of this study was to systematically review the comparative evidence regarding the effectiveness and safety of the 2 formulations when used for spinal anesthesia for adult noncesarean delivery surgery. METHODS: Key electronic databases were searched for randomized controlled trials, excluding cesarean delivery surgeries under spinal anesthesia, without any language or date restrictions. The primary outcome measure for this review was the failure of spinal anesthesia. Two independent reviewers selected the studies and extracted the data. Results were expressed as relative risk (RR) or mean differences (MDs) with 95% confidence intervals (CIs). RESULTS: Seven hundred fifty-one studies were identified between 1946 and 2016. After screening, there were 16 randomized controlled clinical trials, including 724 participants, that provided data for the meta-analysis. The methodological reporting of most studies was poor, and appropriate judgment of their individual risk of bias elements was not possible. There was no difference between the 2 drugs regarding the need for conversion to general anesthesia (RR, 0.60; 95% CI, 0.08-4.41; P = .62; I = 0%), incidence of hypotension (RR, 1.15; 95% CI, 0.69-1.92; P = .58; I = 0%), nausea/vomiting (RR, 0.29; 95% CI, 0.06-1.32; P = .11; I = 7%), or onset of sensory block (MD = 1.7 minutes; 95% CI, -3.5 to 0.1; P = .07; I = 0%). The onset of motor block (MD = 4.6 minutes; 95% CI, 7.5-1.7; P = .002; I = 78%) was significantly faster with hyperbaric bupivacaine. Conversely, the duration of motor (MD = 45.2 minutes; 95% CI, 66.3-24.2; P < .001; I = 87%) and sensory (MD = 29.4 minutes; 95% CI, 15.5-43.3; P < .001; I = 73%) block was longer with isobaric bupivacaine. CONCLUSIONS: Both hyperbaric bupivacaine and isobaric bupivacaine provided effective anesthesia with no difference in the failure rate or adverse effects. The hyperbaric formulation allows for a relatively rapid motor block onset, with shorter duration of motor and sensory block. The isobaric formulation has a slower onset and provides a longer duration of both sensory and motor block. Nevertheless, the small sample size and high heterogeneity involving these outcomes suggest that all the results should be treated with caution.

Neurotoxicity Comparison of Two Types of Local Anaesthetics: Amide-Bupivacaine versus Ester-Procaine.

Local anaesthetics (LAs) may lead to neurological complications, but the underlying mechanism is still unclear. Many neurotoxicity research studies have examined different LAs, but none have comprehensively explored the distinct mechanisms of neurotoxicity caused by amide- (bupivacaine) and ester- (procaine) type LAs. Here, based on a CCK8 assay, LDH assay, Rhod-2-AM and JC-1 staining, 2',7'-dichlorohy-drofluorescein diacetate and dihydroethidium probes, an alkaline comet assay, and apoptosis assay, we show that both bupivacaine and procaine significantly induce mitochondrial calcium overload and a decline in the mitochondrial membrane potential as well as overproduction of ROS, DNA damage and apoptosis (P < 0.05). There were no significant differences in mitochondrial injury and apoptosis between the bupivacaine and procaine subgroups (P > 0.05). However, to our surprise, the superoxide anionic level after treatment with bupivacaine, which leads to more severe DNA damage, was higher than the level after treatment with procaine, while procaine produced more peroxidation than bupivacaine. Some of these results were also affirmed in dorsal root ganglia neurons of C57 mice. The differences in the superoxidation and peroxidation induced by these agents suggest that different types of LAs may cause neurotoxicity via different pathways. We can target more accurate treatment based on their different mechanisms of neurotoxicity.

Addition of Liposome Bupivacaine to Bupivacaine HCl Versus Bupivacaine HCl Alone for Interscalene Brachial Plexus Block in Patients Having Major Shoulder Surgery.

BACKGROUND AND OBJECTIVES: We examined whether liposome bupivacaine (Exparel) given in the interscalene brachial plexus block lowers pain in the setting of multimodal postoperative pain management for major shoulder surgery. METHODS: Fifty-two adult patients were randomized to receive either 5 mL of 0.25% bupivacaine HCl immediately followed by 10 mL of liposome bupivacaine 133 mg (n = 26) or 15 mL of 0.25% standard bupivacaine alone (n = 26) in interscalene brachial plexus block. The primary outcome (worst pain in the first postoperative week) was assessed by the Modified Brief Pain Inventory short form. Secondary outcomes were overall satisfaction with analgesia (OBAS), functionality of the surgical arm, sleep duration, time to first opioid (tramadol) request and opioid consumption (mEq), sensory-motor block characteristics, and the occurrence of adverse effects. RESULTS: Worst pain was lower in patients given liposome bupivacaine added to standard bupivacaine than in patients given standard bupivacaine alone (generalized estimating equation [GEE] estimated marginal mean values, 3.6 ± 0.3 vs 5.3 ± 0.4 points on the Numeric Rating Scale, respectively, although the effect was modest, 1.6 ± 0.5; 95% confidence interval, 0.8-2.5). Total OBAS scores indicated greater satisfaction (GEE estimated marginal mean values, 1.8 ± 0.3 vs 3.3 ± 0.4 on total OBAS, respectively, with modest effect, difference, 1.4 ± 0.5; 95% confidence interval, 0.5-2.4). There were no differences in any of the other secondary outcomes. CONCLUSIONS: Liposome bupivacaine added to standard bupivacaine may lower pain and enhance patient's satisfaction in the first postoperative week even in the setting of multimodal analgesia for major shoulder surgery.This study was registered with clinicaltrials.gov (NCT02554357) on July 11, 2015, by Principal Investigator Catherine Vandepitte, MD.

Intrathecal hyperbaric versus isobaric bupivacaine for adult non-caesarean-section surgery: systematic review protocol.

INTRODUCTION: Bupivacaine is the most commonly used local anaesthetic for spinal anaesthesia (SA). There are two forms of commercially available bupivacaine; isobaric bupivacaine (IB): a formulation with a specific gravity or density equal to cerebrospinal fluid, and hyperbaric bupivacaine (HB): a formulation with density heavier than cerebrospinal fluid. The difference in densities of the two available preparations is believed to affect the diffusion pattern that determines the effectiveness, spread and side-effect profile of bupivacaine. This systematic review will summarise the best available evidence regarding the effectiveness and safety on the use of HB compared with IB, when used to provide SA for surgery. Primarily, we will analyse the need for conversion to general anaesthesia. As secondary outcomes, we will compare the incidence of hypotension, incidence of nausea/vomiting, the onset time and duration of anaesthesia. METHODS AND ANALYSIS: We will search key electronic databases using search strategy (1) injections, spinal OR intrathecal OR subarachnoid; (2) bupivacaine OR levobupivacaine; (3) hypobaric OR isobaric OR plain; (4) baricity. We will search MEDLINE, EMBASE and Cochrane databases, from their inception for randomised controlled trials, with no restrictions on language. Caesarean section surgery will be excluded. 2 reviewers will independently extract the data using a standardised form. Extracted items will include study characteristics, risk of bias domains, as per modified Cochrane risk of bias, participant disposition and study outcomes. We will conduct a meta-analysis for variables that can be compared across the studies. We will evaluate clinical heterogeneity by qualitatively appraising differences in study characteristics in participants, interventions and the outcomes assessed. We will report our findings as relative risks (dichotomous), and weighted mean differences (continuous) for individual outcomes, along with their 95% CIs. ETHICS AND DISSEMINATION: We plan to submit, and will publish, our findings in a peer-reviewed scientific journal, and present our results at national and international meetings. TRIAL REGISTRATION NUMBER: CRD42015017672.

Liposomal Bupivacaine for Pain Control After Anterior Cruciate Ligament Reconstruction: A Prospective, Double-Blinded, Randomized, Positive-Controlled Trial.

BACKGROUND: Local anesthetics are commonly administered into surgical sites as a part of multimodal pain control regimens. Liposomal bupivacaine is a novel formulation of bupivacaine designed for slow diffusion of a single dose of local anesthetic over a 72-hour period. While early results are promising in various settings, no studies have compared pain management regimens containing liposomal bupivacaine to traditional regimens in patients undergoing anterior cruciate ligament (ACL) reconstruction. PURPOSE: To evaluate liposomal bupivacaine in comparison with 0.25% bupivacaine hydrochloride (HCl) for pain control after ACL reconstruction. STUDY DESIGN: Randomized controlled trial; Level of evidence, 1. METHODS: A total of 32 adult patients undergoing primary ACL reconstruction with a soft tissue quadriceps tendon autograft between July 2014 and March 2015 were enrolled. All patients received a femoral nerve block immediately before surgery. Patients then received either a 40-mL suspension of 20 mL Exparel (1 vial of bupivacaine liposome injectable suspension) and 20 mL 0.9% injectable saline or 20 mL 0.5% bupivacaine HCl and 20 mL 0.9% injectable saline, which was administered into the graft harvest site and portal sites during surgery. Patients were given either a postoperative smartphone application or paper-based journal to record data for 1 week after ACL reconstruction. RESULTS: Of the 32 patients recruited, 29 patients were analyzed (90.6%). Two patients were lost to follow-up, and 1 was excluded because of a postoperative hematoma. There were no statistically significant differences in postoperative pain, medication use, pain location, recovery room time, or mobility between the 2 study groups. CONCLUSION: There were comparable outcomes with 0.25% bupivacaine HCl at a 200-fold lower cost than liposomal bupivacaine. This study does not support the widespread use of liposomal bupivacaine for pain control after ACL reconstruction in the setting of a femoral nerve block. REGISTRATION: ClinicalTrials.gov NCT02189317.

Local, Controlled Delivery of Local Anesthetics In Vivo from Polymer - Xerogel Composites.

PURPOSE: Polymer-xerogel composite materials have been introduced to better optimize local anesthetics release kinetics for the pain management. In a previous study, it was shown that by adjusting various compositional and nano-structural properties of both inorganic xerogels and polymers, zero-order release kinetics over 7 days can be achieved in vitro. In this study, in vitro release properties are confirmed in vivo using a model that tests for actual functionality of the released local anesthetics. METHODS: Composite materials made with tyrosine-polyethylene glycol(PEG)-derived poly(ether carbonate) copolymers and silica-based sol-gel (xerogel) were synthesized. The in vivo release from the composite controlled release materials was demonstrated by local anesthetics delivery in a rat incisional pain model. RESULTS: The tactile allodynia resulting from incision was significantly attenuated in rats receiving drug-containing composites compared with the control and sham groups for the duration during which natural healing had not yet taken place. The concentration of drug (bupivacaine) in blood is dose dependent and maintained stable up to 120 h post-surgery, the longest time point measured. CONCLUSIONS: These in vivo studies show that polymer-xerogel composite materials with controlled release properties represent a promising class of controlled release materials for pain management.