Local anesthetic failure associated with inflammation: verification of the acidosis mechanism and the hypothetic participation of inflammatory peroxynitrite

A Review of the Lidocaine in the Perioperative Period

This review analyzes the controversies surrounding lidocaine (LIDO), a widely recognized local anesthetic, by exploring its multifaceted effects on pain control in the perioperative setting. The article critically analyzes debates about lidocaine's efficacy, safety, and optimal administration methods. While acknowledging its well-documented analgesic attributes, the text highlights the ongoing controversies in its application. The goal is to provide clinicians with a comprehensive understanding of the current discourse, enabling informed decisions about incorporating lidocaine into perioperative protocols. On the other hand, emphasizes the common uses of lidocaine and its potential role in personalized medicine. It discusses the medication's versatility, including its application in anesthesia, chronic pain, and cardiovascular diseases. The text recognizes lidocaine's widespread use in medical practice and its ability to be combined with other drugs, showcasing its adaptability for individualized treatments. Additionally, it explores the incorporation of lidocaine into hyaluronic acid injections and its impact on pharmacokinetics, signaling innovative approaches. The discussion centers on how lidocaine, within the realm of personalized medicine, can offer safer and more comfortable experiences for patients through tailored treatments.

Effects of subconjunctival ropivacaine, liposomal bupivacaine, and mepivacaine on corneal sensitivity in healthy horses

OBJECTIVE

To evaluate corneal sensitivity and adverse events following subconjunctival administration of three local anesthetics in horses.

STUDY DESIGN

Randomized, masked, crossover study.

ANIMALS

Twelve healthy adult mares.

METHODS

The subconjunctival space of the treated eye was injected with 0.2 mL of liposomal bupivacaine (1.3%), ropivacaine (0.5%), or mepivacaine (2%). All horses received each medication once and the contralateral eye received saline (control). Corneal touch threshold (CTT) was measured using a Cochet-Bonnet esthesiometer before sedation, after sedation, and at specified intervals until it returned to baseline. Ocular examinations were performed at 24-, 72, and 168 h post-injection to monitor for adverse effects.

RESULTS

The mean total time of anesthesia (TTA) was 168.3 min for ropivacaine, 169.2 min for liposomal bupivacaine, 103.3 min for mepivacaine and 30.7 min for the control. TTA for liposomal bupivacaine (p < .001) and ropivacaine (p = .001) was longer than the control. TTA for mepivacaine was not different from the control (p = .138), liposomal bupivacaine (p = .075) or ropivacaine (p = .150). Injection site hemorrhage reduced TTA regardless of treatments (p = .047). No adverse effects attributed to injections were noted.

CONCLUSION

All three medications were well tolerated. Subconjunctival administration of ropivacaine and liposomal bupivacaine resulted in longer TTAs compared to the control; however, their TTAs were not different from that of mepivacaine.

CLINICAL SIGNIFICANCE

Subconjunctivally administered liposomal bupivacaine and ropivacaine are viable options to provide prolonged corneal analgesia in horses. Future studies are needed to assess the efficacy in diseased eyes.

Evaluating the effect of using anti-stress balls as a distraction technique in reducing pain during inferior alveolar nerve block injection: a randomized clinical trial

OBJECTIVE

The aim of this study is to evaluate the effect of using anti-stress balls in reducing patients' pain during injection of the inferior alveolar nerve block (IANB).

MATERIALS AND METHODS

In this randomized clinical trial, 32 individuals were divided into two groups. The conventional method of anesthesia injection was performed using IANB conventional injection technique. During the injection, individuals in the anti-stress ball group were asked to use the anti-stress ball as a distraction technique. For the control group, no supersede methods were used for pain control. Finally, both groups were asked to record their pain utilizing the numerical rating scale (NRS). The participants' vital signs were monitored before and after injection. Kolmogorov-Smirnov test, independent T-test, and Fisher's exact chi-square test were performed for statistical analysis (α = 0.05).

RESULTS

Sixteen females and 16 males in the age range of 40 to 20 years old participated in this study. The mean pain score in the anti-stress ball group was significantly lower (p < 0.001). In both sexes, the pain score in the anti-stress ball group was significantly lower (males p < 0.001 and females p = 0.001). In addition, in all age ranges, the pain score in the control group was higher except for the above 35 years old participants (p = 0.078). Moreover, there were no significant differences in individuals' vital signs (p > 0.05).

CONCLUSION AND CLINICAL RELEVANCE

Utilizing an anti-stress ball reduces patients' pain significantly during IANB in both sexes and individuals who are below 35 years without changing vital signs.

CLINICAL REGISTRATION NUMBER

IRCT20220815055704N1.

Effect of Local Anesthetic Injections on Subjective Pain Scales in Pediatric Tonsillectomies: A Meta-analysis

OBJECTIVE

To assess the effect of local anesthetic injection on subjective pain scores for pediatric tonsillectomies on postoperative days (PODs) 0 and 1.

DATA SOURCES

A comprehensive literature search was conducted with the PubMed, Embase, Web of Science, and Scopus databases.

REVIEW METHODS

A 2-researcher team following the PRISMA guidelines performed a systematic review and meta-analysis. Studies with original data and a saline injection control arm were selected. Corresponding authors were contacted for missing data. The collated data were analyzed with RevMan version 5.4 (Review Manager; Cochrane Collaboration). Random effects modeling and standard mean difference were utilized to control for heterogeneity. Surgical technique subgroup analysis was performed.

RESULTS

A total of 319 publications were identified, and 8 articles with 13 experimental arms (627 participants) were selected for meta-analysis. Local anesthetic injection was compared with placebo with saline injection. The standard mean difference for POD 0 pain was -0.81 (95% CI, -1.16 to -0.46; P < .00001) in favor of local anesthetic. The standard mean difference for POD 1 was -1.13 (95% CI, -1.48 to -0.78; P < .00001) in favor of local anesthetic. Subgroup analysis by surgical technique showed a less robust effect for cautery excision (-1.01 [95% CI, -1.37 to -0.66]) vs cold excisional technique (-1.19 [95% CI, -1.64 to -0.74]), with or without cautery-based hemostasis.

CONCLUSIONS

A local anesthetic injection during a pediatric tonsillectomy reduces postoperative pain on POD 0 and 1. Further analysis on total narcotic use and postoperative complications would benefit surgeon decision making.

Does a New Modification of the Two-Step Injection Technique for Inferior Alveolar Nerve Block Reduce Pain Compared to the Conventional Technique? A Randomized Clinical Trial

Background. The ability to control pain is an essential part of dental procedures and the need for optimal pain control and reduction of discomfort is the primary concern of every dentist. This study aims to compare the pain and vital signs during inferior alveolar nerve block between conventional and a new modification of the two-step injection techniques. Methods. In this institutional single-blind randomized clinical trial, attendees of dental school at Mazandaran University of Medical Sciences from February to May 2022 were included. Inclusion criteria were 20–60 years old and healthy (ASA1) individuals who were willing to participate in this study. Individuals who were taking medications affecting their understanding of pain and patients with active infections at the injection site were excluded. These individuals were divided into two groups. First, superficial anesthesia was performed and afterward, conventional and two-step injection techniques were performed. For the two-step injection method, 6 mm of the needle was injected into the mucosa and one-third of the local anesthetic solution was released from the computer-controlled injection toolkit. Afterward, a 25 mm 30-gauge needle was reinserted into the previous hole delivering the remaining local anesthetic. The pain during injection was measured by a patient-reported numerical rating scale (NRS). Moreover, vital signs were monitored immediately before and after the injection. Kolmogorov–Smirnov test, Mann–Whitney U test, independent T-test, and Fisher’s exact χ2 test were performed for statistical analysis (α = 0.05). Results. This study involved 32 adults aged between 20 and 50 years old with 1 : 1 female/male sex distribution. The pain score was significantly higher in the conventional injection technique compared to the two-step injection technique in all sex and age groups. There were no significant differences in vital signs between the conventional and two-step injection techniques. There was no significant difference in the mean pain scores of females and males, regardless of their injection techniques. Conclusion. Utilizing the two-step injection technique in patients for inferior alveolar block reduces pain during injection without altering patients’ vital signs significantly. This trial is registered with IRCT20220106053646N1.

Cardiovascular Response of Aged Outpatients With Systemic Diseases During Tooth Extraction: A Single-Center Retrospective Observational Study

Background

Aged people are maintaining many natural teeth due to improved oral health. However, compromised general health and poor oral hygiene habits at earlier ages resulted in poor status of preserved teeth. Therefore, tooth extraction is required in many aged people. More knowledge is needed because there are many risk factors during the surgery in frail aged adults. The aim of this study was to evaluate the cardiovascular response of such a population during tooth extraction and analyze risk factors to provide clinical guidance.

Methods

A retrospective study was performed on aged patients with systemic diseases who underwent tooth extraction. Data regarding demographic profiles and cardiovascular parameters of heart rate and blood pressure were collected preoperative, when local anesthesia was administered, at the beginning of tooth extraction, 5 min after tooth extraction, and postoperative. The effects of risk factors, including age, sex, and systemic diseases on these parameters were analyzed with a multilevel model.

Results

Heart rate (HR), systolic blood pressure (SBP), and diastolic blood pressure (DBP) of aged patients increased significantly when performing local anesthesia and tooth extraction. During the operation, the older patients (β = 2.011, P = 0.005) and the diabetics (β = 3.902, P < 0.0001) were associated with higher SBP, while those with more tooth extractions exhibited higher HR (β = 0.893, P = 0.007). Women patients showed both significantly elevated HR (β = 1.687, P < 0.0001) and SBP (β = 2.268, P < 0.0001). However, for coronary artery disease patients, HR (β = −2.747, P < 0.0001) and blood pressure [SBP (β = −4.094, P < 0.0001) and DBP (β = −0.87, P = 0.016)] were markedly lower than those of patients without a diagnosis of coronary artery disease.

Conclusion

Cardiovascular response of aged outpatients with systemic diseases during tooth extraction is quite significant. Age, sex, systemic diseases, and the number of tooth extraction could be risk factors closely associated with cardiovascular response. The findings might provide safety guidance for dentists on tooth extraction in this population.

Effects of treatment with local anesthetics on RANKL expression in MG63 and PDL cells

Background/purpose

Local anesthesia (LA) application is a routine dental work in clinic. The aim of present study was to evaluate the extent of biologic effects of LA on periodontal ligaments (PDL) or bone cells (MG63).

Materials and methods

Local anesthetics (LAs) at different concentrations were added to PDL and MG 63 cells. The viability of the cells was analyzed using an MTT assay. The inflammatory markers, COX-2, IL-1, IL-6 and TNF-A, of PDL and MG63 cells treated with LAs were analyzed with a Western blot assay. The extract medium of the LA-treated PDL cells was added to the MG63 cells for subsequent culture and to examine the RANKL, ALP, and OPG expression. The data were statistically analyzed with p < 0.05 set as an indication of significance.

Results

The viability of the PDL and MG63 cells was less 50% at LAs concentrations above the 10 mM. At high LA concentrations, the PDL and MG63 cells treated with LAs became spherical in shape, or vesicles developed in the cytoplasm. The IL-1, IL-6, and TNF-A expression in the PDL groups showed no statistical differences between Septanest and Scandonest (p > 0.05). The RANKL expression in the MG63 cells increased as the Septanest and Scandonest concentrations were increased in the PDL extract medium (p < 0.05) after 48 h of culturing.

Conclusion

The LAs with adrenaline increased inflammation in the PDL and MG63 cells. The LA-treated PDL extract medium increased the RANKL expression in the MG63 cells.

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.

Efficacy of Lignocaine with Buprenorphine versus Lignocaine in the Management of Postoperative Pain after Minor Oral Surgical Procedures: A Systematic Review and Meta-analysis

We aimed to review the efficacy of lignocaine with buprenorphine versus lignocaine alone in the management of postoperative pain after minor oral surgical procedures. Randomized controlled trials evaluating the efficacy of use of lignocaine with buprenorphine versus lignocaine for intra-oral procedures were included by searching multiple databases. Outcomes assessed were onset of the time of anesthesia in seconds, duration of postoperative analgesia, postoperative pain (maximal follow-up), the number of rescue analgesics required, and adverse events. The search strategy yielded 167 publications for the title and abstract screening out of which only two trials were included for full-text screening. There was considerable heterogeneity among the included studies with regards to the outcomes assessed. The need for rescue analgesics was the only outcome that was included for meta-analyses. Forest plot showed that lignocaine with buprenorphine compared to lignocaine showed a significantly lower requirement of rescue analgesics (-0.22[-2.9,-1.55]). No trial reported any adverse effects. The results show that lignocaine with buprenorphine is effective in reducing the number of rescue analgesics required by the patient.

A primer on tissue pH and local anesthetic potency

The relationship between pH, pK_a, and degree of local anesthetic ionization is quantified by the Henderson-Hasselbalch equation. As presented in standard textbooks, the effect of pH on the degree of ionization of any particular local anesthetic is not immediately clear due to the x-axis displaying pH - pK_a, which requires conversion to pH, based on the pK_a for each local anesthetic, a complex process. We present a graphical solution that clarifies the interrelationships between pH, pK_a, and degree of ionization by plotting pK_a on the x-axis versus the percentage of unionized local anesthetic on the y-axis. The vertical intercept from the x-axis to the pH curves allows rapid and accurate estimation of the degree of ionization of any local anesthetic of known pK_a.

Liposomal anesthetic gel for pain control during periodontal therapy in adults: a placebo-controlled RCT

INTRODUCTION

Periodontal therapy usually requires local anesthesia. If effective, a non-invasive, liposomal anesthetic gel could increase the levels of acceptance of patients in relation to periodontal therapy.

OBJECTIVE

This study investigated the efficacy of liposomal anesthetic gel for pain control during periodontal therapy.

METHODOLOGY

Forty volunteers with moderate to severe chronic periodontitis were recruited, of which at least three sextants required periodontal therapy. At least one of the selected teeth had one site with a probing depth of ≥4 mm. The volunteers received the following three gels: a placebo, lidocaine/prilocaine (Oraqix®), or a liposomal lidocaine/prilocaine, which were applied to different sextants. Pain frequency was registered during treatment and the volunteers received a digital counter to register any painful or uncomfortable experiences. At the end of each session, the volunteers indicated their pain intensity using rating scales (NRS-101 and VRS-4). The volunteers had their hemodynamic parameters measured by a non-invasive digital monitor.

RESULTS

Pain frequency/intensity did not show statistical difference between intervention groups. The tested gels did not interfere with the hemodynamic indices. Dental anxiety, suppuration and probing depth could influence pain during periodontal therapy.

CONCLUSION

Our results suggest limited indications for the use of non-invasive anesthesia when used for scaling and root planing. Intra-pocket anesthetic gel could be a good option for anxious patients, or those who have a fear of needles.

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

Purpose

Currently available local anesthetics have not demonstrated sufficient analgesia beyond 12–24 h postoperatively. The purpose of the study was to assess the safety and efficacy of HTX-011 (bupivacaine and meloxicam in Biochronomer^® polymer technology), a long-acting investigational anesthetic, in reducing both postoperative pain over 72 h and postoperative opioid use compared to bupivacaine hydrochloride (HCl).

Methods

A phase 3, randomized, double-blind, active-controlled multi-center study (EPOCH 2; NCT03237481) in subjects undergoing unilateral open inguinal herniorrhaphy with mesh placement was performed. Subjects randomly received a single intraoperative dose of HTX-011, immediate-release bupivacaine HCl, or saline placebo prior to closure.

Results

The study evaluated 418 subjects, and the primary and all key secondary efficacy endpoints were in favor of HTX-011. HTX-011 reduced mean pain intensity by 23% versus placebo (primary endpoint; p < 0.001) and by 21% versus bupivacaine HCl (p < 0.001) with significant reductions in the number of patients experiencing severe pain. Opioid consumption over 72 h was reduced by 38% versus placebo (p < 0.001) and 25% versus bupivacaine HCl (p = 0.024). Overall, 51% of HTX-011 subjects were opioid-free through 72 h (versus 22% for placebo [p < 0.001] and 40% for bupivacaine HCl [p = 0.049]). HTX-011 was generally well-tolerated with fewer opioid-related adverse events reported compared to the bupivacaine HCl and placebo and no evidence of local anesthetic systemic toxicity.

Conclusions

HTX-011 demonstrated significant improvement in postoperative pain control and a clinically meaningful reduction in opioid consumption when compared to the most widely used local anesthetic, bupivacaine HCl.

Pain management in abdominal surgery

BACKGROUND

Abdominal surgery has undergone major changes during the last two decades with a general shift from open, invasive surgery to closed minimally invasive surgery. Accordingly, pain management strategies have also changed, especially with the introduction of ultrasound-guided abdominal wall blocks. Despite laparoscopic abdominal surgery classified as minimal, pain can be quite significant and needs to be addressed appropriately.

PURPOSE

This narrative review focuses on adequate pain strategies for various types of surgery. The respective techniques are described and examples of specific pain management strategies given. Advantages and disadvantages of techniques are discussed. This review can serve as a sort of empirical guideline and orientation for the reader to develop their own strategy as well as bringing surgeons up-to-date with the latest anesthetic techniques.

CONCLUSION

Pain is not less or less relevant in minimally invasive surgery. New hallmarks of a multimodal pain strategy are abdominal wall blocks, either as single shot or continuously. Minor open surgery is best performed under a combination of loco-regional blocks and continuous sedation. Abdominal wall blocks, NSAIDs, and short-acting opioids given by nurses or as PCA present the best multimodal pain strategy in abdominal surgery. Epidural analgesia and spinal anesthesia have become second-line options or are reserved for specific patient morbidities or surgical requirements.

Disease-Triggered Drug Release Effectively Prevents Acute Inflammatory Flare-Ups, Achieving Reduced Dosing

For conditions with inflammatory flare-ups, fast drug-release from a depot is crucial to reduce cell infiltration and prevent long-term tissue destruction. While this concept has been explored for chronic diseases, preventing acute inflammatory flares has not been explored. To address this issue, a preventative inflammation-sensitive system is developed and applied to acute gout, a condition where millions of inflammatory cells are recruited rapidly, causing excruciating and debilitating pain. Rapid drug release is first demonstrated from a pH-responsive acetalated dextran particle loaded with dexamethasone (AcDex-DXM), reducing proinflammatory cytokines in vitro as efficiently as free drug. Then, using the air pouch model of gout, mice are pretreated 24 h before inducing inflammation. AcDex-DXM reduces overall cell infiltration with decreased neutrophils, increases monocytes, and diminishes cytokines and chemokines. In a more extended prophylaxis model, murine joints are pretreated eight days before initiating inflammation. After quantifying cell infiltration, only AcDex-DXM reduces the overall joint inflammation, where neither free drug nor a conventional drug-depot achieves adequate anti-inflammatory effects. Here, the superior efficacy of disease-triggered drug-delivery to prevent acute inflammation is demonstrated over free drug and slow-release depots. This approach and results promise exciting treatment opportunities for multiple inflammatory conditions suffering from acute flares.

Staphylococcus aureus produces pain through pore-forming toxins and neuronal TRPV1 that is silenced by QX-314

The hallmark of many bacterial infections is pain. The underlying mechanisms of pain during live pathogen invasion are not well understood. Here, we elucidate key molecular mechanisms of pain produced during live methicillin-resistant Staphylococcus aureus (MRSA) infection. We show that spontaneous pain is dependent on the virulence determinant agr and bacterial pore-forming toxins (PFTs). The cation channel, TRPV1, mediated heat hyperalgesia as a distinct pain modality. Three classes of PFTs-alpha-hemolysin (Hla), phenol-soluble modulins (PSMs), and the leukocidin HlgAB-directly induced neuronal firing and produced spontaneous pain. From these mechanisms, we hypothesized that pores formed in neurons would allow entry of the membrane-impermeable sodium channel blocker QX-314 into nociceptors to silence pain during infection. QX-314 induced immediate and long-lasting blockade of pain caused by MRSA infection, significantly more than lidocaine or ibuprofen, two widely used clinical analgesic treatments.

Efficacy of Paromomycin-Chloroquine Combination Therapy in Experimental Cutaneous Leishmaniasis

The 4-aminoquinoline chloroquine (CQ) is clinically used in combination with doxycycline to cure chronic Q fever, as it enhances the activity of the antibiotic against the causative bacterium Coxiella burnetii residing within macrophage phagolysosomes. As there is a similar cellular host-pathogen biology for Leishmania parasites, this study aimed to determine whether such an approach could also be the basis for a new, improved treatment for cutaneous leishmaniasis (CL). We have evaluated the in vitro and in vivo activities of combinations of CQ with the standard drugs paromomycin (PM), miltefosine, and amphotericin B against Leishmania major and Leishmania mexicana In 72-h intracellular antileishmanial assays, outcomes were variable for different drugs. Significantly, the addition of 10 μM CQ to PM reduced 50% effective concentrations (EC50s) by over 5-fold against L. major and against normally insensitive L. mexicana parasites. In murine models of L. major and L. mexicana CL, daily coadministration of 50 mg/kg of body weight PM and 25 mg/kg CQ for 10 days resulted in a significant reduction in lesion size but not in parasite load compared to those for mice given the same doses of PM alone. Overall, our data indicate that PM-CQ combination therapy is unlikely to be a potential candidate for further preclinical development.

Surface-functionalized cockle shell-based calcium carbonate aragonite polymorph as a drug nanocarrier

Calcium carbonate aragonite polymorph nanoparticles derived from cockle shells were prepared using surface functionalization method followed by purification steps. Size, morphology, and surface properties of the nanoparticles were characterized using transmission electron microscopy, field emission scanning electron microscopy, dynamic light scattering, zetasizer, X-ray powder diffraction, and Fourier transform infrared spectrometry techniques. The potential of surface-functionalized calcium carbonate aragonite polymorph nanoparticle as a drug-delivery agent were assessed through in vitro drug-loading test and drug-release test. Transmission electron microscopy, field emission scanning electron microscopy, and particle size distribution analyses revealed that size, morphology, and surface characterization had been improved after surface functionalization process. Zeta potential of the nanoparticles was found to be increased, thereby demonstrating better dispersion among the nanoparticles. Purification techniques showed a further improvement in the overall distribution of nanoparticles toward more refined size ranges <100 nm, which specifically favored drug-delivery applications. The purity of the aragonite phase and their chemical analyses were verified by X-ray powder diffraction and Fourier transform infrared spectrometry studies. In vitro biological response of hFOB 1.19 osteoblast cells showed that surface functionalization could improve the cytotoxicity of cockle shell–based calcium carbonate aragonite nanocarrier. The sample was also sensitive to pH changes and demonstrated good abilities to load and sustain in vitro drug. This study thus indicates that calcium carbonate aragonite polymorph nanoparticles derived from cockle shells, a natural biomaterial, with modified surface characteristics are promising and can be applied as efficient carriers for drug delivery.

Effectiveness of the addition of Lidocaine to a hemostatic, bioresorbable putty in the treatment of iliac crest donor site pain

Background

The harvest of iliac crest bone grafts (ICBG) is associated with relevant donor site pain, but may be lowered by the application of lidocaine loaded on biodegradable, hemostatic putty for sustained local analgesic release. The goal of this double-blind controlled trial was to assess the efficacy of adding lidocaine to a hemostatic putty (Orthostat ™) to treat donor site pain following harvest of ICBG in foot and ankle procedures.

Methods

After ICBG harvest during a foot and ankle procedure, the resulting bone defect was either filled with Orthostat™ (n = 7) or with the same hemostatic putty loaded with lidocaine (Orthostat-L™, n = 7). During the first 72 postoperative hours, donor site and surgical site pain were managed by patient controlled morphine delivery and a peripheral nerve block. Donor site pain was periodically quantified on a Visual Analog (VAS) and a Wong Baker FACES scale. Pain scores were plotted over time to calculate the area under the curve (AUC) to quantify the overall pain experienced in specific time intervals.

Results

Orthostat-L™ significantly reduced donor site pain over the first 12 hours postoperatively as evidenced by a significant decrease of the AUC in both VAS (p = 0.0366) and Wong Baker FACES pain score plots (p = 0.0024). Cumulated morphine uses were not significantly decreased with Orthostat-L™.

Conclusion

The addition of lidocaine to a hemostatic putty offers a significant ICBG donor site pain reduction over the first 12 postoperative hours.

Trial registration

ClinicalTrials.gov NCT01504035. Registered January 2nd 2012.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2474-15-415) contains supplementary material, which is available to authorized users.

Interaction of local anesthetics with biomembranes consisting of phospholipids and cholesterol: mechanistic and clinical implications for anesthetic and cardiotoxic effects

Despite a long history in medical and dental application, the molecular mechanism and precise site of action are still arguable for local anesthetics. Their effects are considered to be induced by acting on functional proteins, on membrane lipids, or on both. Local anesthetics primarily interact with sodium channels embedded in cell membranes to reduce the excitability of nerve cells and cardiomyocytes or produce a malfunction of the cardiovascular system. However, the membrane protein-interacting theory cannot explain all of the pharmacological and toxicological features of local anesthetics. The administered drug molecules must diffuse through the lipid barriers of nerve sheaths and penetrate into or across the lipid bilayers of cell membranes to reach the acting site on transmembrane proteins. Amphiphilic local anesthetics interact hydrophobically and electrostatically with lipid bilayers and modify their physicochemical property, with the direct inhibition of membrane functions, and with the resultant alteration of the membrane lipid environments surrounding transmembrane proteins and the subsequent protein conformational change, leading to the inhibition of channel functions. We review recent studies on the interaction of local anesthetics with biomembranes consisting of phospholipids and cholesterol. Understanding the membrane interactivity of local anesthetics would provide novel insights into their anesthetic and cardiotoxic effects.