Concentrations Of Mepivacaine Research Articles

Diabetic Neuropathy and Minimum Effective Anesthetic Concentration of Mepivacaine for Axillary Brachial Plexus Block: A Prospective Observational Study.

Nerves in patients with diabetic neuropathy (DN) show increased susceptibility to local anesthetics, potentially requiring a decreased dose. We investigated whether the minimum effective anesthetic concentration (MEAC) of mepivacaine for successful axillary block is lower in patients with DN than in those without. This prospective observational study included patients with DN (n = 22) and without diabetes (n = 22) at a tertiary care center. Patients received an ultrasound-guided axillary block with 30 mL of mepivacaine for anesthesia. The mepivacaine concentration used in each patient was calculated using Dixon's up-and-down method. A block was considered successful if all four sensory nerves had a score of 1 or 2 within 30 min with no pain during surgery. The primary outcome was the MEAC of mepivacaine, and the secondary outcomes included the minimal nerve stimulation intensity for the musculocutaneous nerve and the occurrence of adverse events. The MEAC50 was 0.55% (95% CI 0.33-0.77%) in patients without diabetes and 0.58% (95% CI 0.39-0.77%) in patients with DN (p = 0.837). The MEAC90 was 0.98% (95% CI 0.54-1.42%) in patients without diabetes and 0.96% (95% CI 0.57-1.35%) in patients with DN (p = 0.949). The stimulation threshold for the musculocutaneous nerve was significantly different between groups (0.49 mA vs. 0.19 mA for patients with vs. without diabetes; p = 0.002). In conclusion, the MEAC of mepivacaine for a successful axillary block is not lower in patients with DN.

The concentration of lidocaine and mepivacaine measured in synovial fluid of different joints of horses after single intra-articular injection.

To determine the synovial fluid (SF) concentrations of lidocaine and mepivacaine after intra-articular injection with clinically relevant doses to the distal interphalangeal (DIP), metacarpophalangeal (MCP), middle carpal (MC), and tarsocrural (TC) joint at two different time points after injection in order to be able to compare concentrations with previously established concentrations associated with cytotoxicity and antimicrobial activity. In the first of two experiments, 20 joints (5 MC, 5 MCP, 10 DIP joints) of five horses under general anesthesia were injected with clinically referenced doses of 2% lidocaine. Simultaneously, the horses had 19 joints (5 MC, 5 MCP, 9 DIP joints) injected with clinically referenced doses of 2% mepivacaine. Synovial fluid samples were collected ~7 min after injection. In experiment 2, 23 joints of seven horses under standing sedation were injected with clinically referenced doses of 2% lidocaine. Similarly, the horses had 21 joints injected with 2% mepivacaine. Synovial fluid samples were collected ~23 min after injection. The concentration of mepivacaine and lidocaine in the obtained SF samples was assessed using high-performance-liquid-chromatography with mass spectrometry detection (HPLC MS). Synovial fluid was obtained 6.8 ± 1.5 (experiment 1) and 23 ± 4.3 (experiment 2) min following intra-articular injection of mepivacaine and lidocaine. Synovial fluid concentrations of experiment 1 for lidocaine and mepivaciane were 6.46-19.62 mg/mL (mean 11.96 ± SD 3.89 mg/mL) and 5.01-13.38 mg/mL (mean 8.18 ± SD 1.76 mg/mL), respectively. In experiment 2, concentrations were 2.94-10.40 mg/mL (mean 6.31± SD 2.23 mg/mL) for lidocaine and 2.10-8.70 mg/mL (mean 4.97 ± SD 1.77 mg/mL) for mepivacaine. Intra-articular LA injections in horses resulted in SF concentrations above those previously associated with cytotoxic effects in vitro but also above those associated with beneficial antimicrobial activities. Local anesthetic concentration was 33-60% lower after 23 min (experiment 2) than after 7 min (experiment 1).

MicroRNA-183-5p protects human derived cell line SH-SY5Y cells from mepivacaine-induced injury

ABSTRACT With the gradual recognition of the side effects of local anesthetics, the nerve injury caused by local anesthetics has received growing attention. This research intended to delve into miR-183-5p changes in mepivacaine-mediated SH-SY5Y cell injury, as well as its modulatory mechanism on cell apoptosis. RT-qPCR was adopted for assaying miR-183-5p and PDCD4 mRNA expression. Our team respectively transfected miR-183-5p mimic and inhibitor to enhance or inhibit miR-183-5p function. We employed Western blot for detecting PDCD4 protein levels, as well as flow cytometry and Hoechst 33342/PI double staining for determining cell apoptosis rate. Additionally, our crew applied an ELISA kit for measuring TNF-α, IL-1β, IL-6, and IL-8 contents. The level of reactive oxygen species (ROS) production was examined by the Image-iT LIVE Green ROS detection Kit. As well as dual-luciferase reporter experiment for verifying the targeting link of miR-183-5p with PDCD4. In mepivacaine-induced cell apoptosis in SH-SY5Y cells, miR-183-5p expression was down-regulated. TNF-α, IL-1β, IL-6, and IL-8 contents were elevated. The rate of apoptosis increased visibly, cleaved caspase-3 and Bax levels waxed, whereas Bcl-2 level waned. MiR-183-5p could alleviate the damaging impact of mepivacaine. Dual-luciferase reporter experiments demonstrated that miR-183-5p directly targeted PDCD4. Collectively, we concluded that a high concentration of mepivacaine can cause SH-SY5Y cell damage, miR-183-5p functions crucially in mepivacaine-mediated cell damage. This study provides a theoretical basis for elucidating the mechanism of mepivacaine-induced nerve cell damage, and overexpressed miR-183-5p likely become a novel strategy to combat mepivacaine-induced nerve damage. Abbreviations: miRNA: Micro RNA; PDCD4: Programmed Cell Death 4; MDA: Malondialdehyde; SOD: Superoxide Dismutase; ROS: Reactive Oxygen Species; WT: Wild Type; Mut: Mutant; UTR: Untranslated Region; IL-6: Interleukin-6; IL-1β: Interleukin-1β; TNF-α: Tumor Necrosis Factor-α; IL-8: Interleukin-8; COX-2: Cyclooxygenase-2; iNOS: inducible NOS; MEP: Mepivacaine

Systemic and local effects of lidocaine or mepivacaine when used for intravenous regional anaesthesia of the distal limb in standing sedated horses.

Local anaesthetics are being combined clinically with amikacin in intravenous regional limb perfusion (IVRLP), with limited knowledge on the analgesia provided and its onset and duration of action after tourniquet application and release. To evaluate the systemic clinical effect, limb withdrawal to nociceptive stimulation, and plasma and synovial fluid concentrations after IVRLP with lidocaine or mepivacaine in standing sedated horses. Prospective, controlled, randomised, cross-over study. Six healthy adult horses were sedated and received IVRLP with lidocaine, mepivacaine or saline (negative control), or perineural anaesthesia of the medial and lateral palmar and palmar metacarpal nerves (positive control) in one forelimb with a 3-week washout period between trials. Electrical and mechanical stimuli were used to test nociceptive threshold of the limb before and after IVRLP/perineural anaesthesia. For lidocaine and mepivacaine trials, blood was collected from the jugular vein and synovial fluid from the radiocarpal joint before, during and out to 24hours after IVRLP. Drug concentrations were measured using high-performance liquid chromatography. Nociceptive thresholds for lidocaine, mepivacaine and perineural anaesthesia trials were significantly increased compared with saline and baseline values at 10, 20 and 30minutes, with no differences between anaesthetic trials. During this time, horses had lower heart rates than IVRLP with saline. After tourniquet release at 30minutes, nociceptive thresholds for lidocaine and mepivacaine trials gradually returned to baselines, whereas perineural anaesthesia trial remained unchanged out to an hour. Plasma lidocaine and mepivacaine concentrations were ≤50ng/mL while the tourniquet was in place, significantly increasing 10minutes after tourniquet release. Maximal lidocaine and mepivacaine concentrations in synovial fluid were reached 25minutes after IVRLP injection. Amikacin was not included in the perfusate. Similar to perineural anaesthesia, IVRLP with lidocaine or mepivacaine provides anti-nociception to the distal limb in standing sedated horses while a tourniquet is applied with concentrations remaining below toxic levels in plasma and synovial fluid.

The antimicrobial activity of bupivacaine, lidocaine and mepivacaine against equine pathogens: An investigation of 40 bacterial isolates

Lameness is the most commonly reported health problem in horses, and lameness investigations which include local anaesthetic injections are routinely performed by equine practitioners. Through this process, bacteria can enter the tissues perforated by the needle and may cause local infections at the injection site. The objective of this in vitro study was to investigate if local anaesthetics at concentrations available in commercially available solutions could inhibit growth and/or kill bacteria that could be inoculated into the synovial space or soft tissues during injection. This study evaluated the antimicrobial activity of the local anaesthetics bupivacaine, lidocaine and mepivacaine against 40 equine clinical bacterial isolates of the Actinobacillus, Corynebacterium, Enterobacter, Escherichia, Pseudomonas, Rhodococcus, Staphylococcus and Streptococcus genera. Minimum inhibitory and minimum bactericidal concentrations (MICs and MBCs) were determined by the broth microdilution method.Clinically applied concentrations of bupivacaine, lidocaine, and mepivacaine inhibited visual growth of 93%, 93%, and 80% of isolates tested, respectively. For the majority (80%) of the inhibited isolates, the concentrations were also bactericidal. The tested local anaesthetics possessed antimicrobial activity against equine pathogens at concentrations that are routinely applied in clinical cases. However, this antimicrobial activity should not discourage antiseptic preparation prior to local anaesthetic injections.

Single-dose local anesthetics exhibit a type-, dose-, and time-dependent chondrotoxic effect on chondrocytes and cartilage: a systematic review of the current literature.

Many studies have shown that local anesthetics may impede chondrocyte metabolism. However, the influence of a single-dose local anesthetics is controversial. The aim of this metaanalysis was to review the literature for studies investigating the cytotoxic effects of single-dose local anesthetics on chondrocytes and cartilage. A comprehensive literature search was performed using established search engines (Medline, Embase) to identify studies, investigating the influence of single-dose local anesthetics on cartilage. The systematic analysis included the influence on histology, cell viability, morphology, and matrix production depending upon dose, exposure time, and type of local anesthetics. Twelve studies with four different local anesthetics were included in this metaanalysis. Bupivacaine and lidocaine were found to be more chondrotoxic than mepivacaine and ropivacaine. The amount of dead cells increased in a substance-, dose-, and time-dependent process. Osteoarthritic cartilage seems to be more vulnerable compared to intact cartilage. The toxic effects occur first in the superficial cartilage layers and include damage to membrane integrity, mitochondrial DNA, and nuclear changes. There is no study that could show a significant chondrotoxic effect with low concentrations of bupivacaine (0.0625%), ropivacaine (0.1 and 0.2%), and mepivacaine (0.5%). The cytotoxicity of local anesthetics on chondrocytes is dependent on dose, time, and type of local anesthetics. Single-dose intra-articular administration of local anesthetics impede chondrocyte metabolism and should be performed only with low concentrations for selected diagnostic purposes and painful joints. The use of lidocaine should be avoided. II.

Chemiluminescence Determination of Local Anaesthetic Mepivacaine in Human Plasma and Pharmaceuticals.

In this study, a new method has been developed for the simple determination of mepivacaine (carbocaine). The method is based on the enhancement effect of mepivacaine in the chemiluminescence (CL) reaction of tris(1,10 phenanthroline) ruthenium(II) with cerium(IV). A mechanism for the CL reaction has been proposed on the basis of UV-Vis, fluorescent and CL spectra. Under optimum conditions, the CL intensity was proportional to the concentration of the drug in solution over the range 0.45-226.25 μg mL-1 (R2 = 0.9996). The LOD was 0.34 μg mL-1 (S/N = 3). LOD was about 10 times lower than the therapeutic concentration of mepivacaine. The percent of relative standard deviation for determination of 11 replicates at level of 9.05 μg mL-1 and 90.50 μg mL-1 of mepivacaine were 1.8 and 3.7%, respectively. The proposed method was applied successfully for the determination of mepivacaine in human plasma and injectable solutions.

Plasma mepivacaine concentrations in patients undergoing third molar surgery.

Local anaesthetic-related systemic toxicity mainly results from elevated plasma concentrations of these drugs. We hypothesized that intraoral injection of submaximal doses of mepivacaine does not lead to toxic levels of this drug in blood. This study evaluated the plasma levels of mepivacaine in third molars surgeries. Twenty-one patients were randomly assigned into two groups: group I (two unilateral third molars; submaximal dose of mepivacaine 108mg with epinephrine 54μg) and group II (four third molars; submaximal dose of mepivacaine 216mg with epinephrine 108μg). Blood samples were collected before anaesthesia, and 5, 10, 15, 20, 30, 40, 60, 90 and 120min after anaesthesia. Individual peak plasma concentrations ranged 0.77-8.31μg/mL (group I) and from 2.36-7.72μg/mL (group II). An increase in the average dose of mepivacaine from 1.88±0.12mg/kg (group I) to 3.35±0.17mg/kg (group II) increased the mean mepivacaine peak plasma levels from 2.33±0.58 to 4.01±0.69μg/mL, respectively. Four patients obtained plasma levels of mepivacaine above the threshold for toxicity (5μg/mL). Toxic levels of mepivacaine are possible, even when a submaximal dose is used. A twofold increase in the dose of mepivacaine caused the mean peak plasma concentration to increase proportionally, indicating that they may be predicted based on the relation of dose per bodyweight.

Antinociceptive effects of topical mepivacaine in a rat model of HIV-associated peripheral neuropathic pain.

BackgroundA consequence of HIV infection is sensory neuropathy, a debilitating condition that degrades the quality of life of HIV patients. Furthermore, life-extending antiretroviral treatment may exacerbate HIV sensory neuropathy. Analgesics that relieve other neuropathic pains show little or no efficacy in ameliorating HIV sensory neuropathy. Thus, there is a need for analgesics for people with this particular pain. While lidocaine is used in the management of painful peripheral neuropathies, another local anesthetic mepivacaine, with a potentially improved bioavailability, could be utilized for the management of HIV neuropathic pain.MethodsThe efficacy of topical anesthetics was evaluated in a preclinical rodent model of painful peripheral neuropathy induced by epineural administration of the HIV envelope protein gp120 delivered using saturated oxidized cellulose implanted around the sciatic nerve. Beginning at 2 weeks following gp120 administration, the effects of local anesthetics topically applied via gauze pads were tested on heat and mechanical hyperalgesia in the hind paw. Rats were tested using several concentrations of mepivacaine or lidocaine during the following 2 weeks.ResultsBy 2 weeks following epineural gp120 implantation, the ipsilateral hind paw developed significant hypersensitivity to noxious pressure and heat hyperalgesia. A short-lasting, concentration-dependent amelioration of pressure and heat hyperalgesia was observed following topical application of mepivacaine to the ipsilateral plantar hind paw. By contrast, topical lidocaine ameliorated heat hyperalgesia in a concentration-dependent manner but not pressure hyperalgesia. Equipotent concentrations of mepivacaine and lidocaine applied topically to the tail of mice significantly increased tail withdrawal latencies in the tail flick test, demonstrating that both local anesthetics attenuate responding to a brief noxious stimulus.ConclusionThese findings showed that mepivacaine, rather than lidocaine, consistently attenuated two distinct symptoms of neuropathic pain and suggest that topical formulations of this local anesthetic could have utility in the alleviation of clinical HIV neuropathic pain.

Injectable bone regeneration biomaterial with analgesic properties

Event Abstract Back to Event Injectable bone regeneration biomaterial with analgesic properties Ahmed E. Al Subaie1, 2, Marco Laurenti1, Iskandar Tamimi1, Laura S. Stone3, Magali Millecamps3, Jake Barralet1 and Faleh Tamimi1 1 McGill University, Faculty of Dentistry, Canada 2 University of Dammam, College of Dentistry, Saudi Arabia 3 McGill University, Edwards Centre for Research on Pain and Faculty of Dentistry,, Canada Introduction: Bone regeneration procedures require invasive and painful interventions. Bone fixation for instance involve invasive incision through skin and muscle to expose bone in order to place fixation plates. Pain management in bone regeneration interventions is limited to the use of drugs such as non-steroidal anti-inflammatories, opioids, acetaminophen and local anesthetics. However, these drugs have several limitations; non-steroidal anti-inflammatories delay bone healing and increase the risk of gastrointestinal diseases[1],[2]. Opioids are controlled drugs, and have major side effects such as constipation and addiction[3]. Acetaminophens are usually not effective in moderate or severe bone pain. Local anesthetics are relatively the most effective and have the least side effects, however they are limited by their short duration of action[3]. Due to the issues raised above, a bone regeneration biomaterial that can relief pain and be applied through minimal invasive procedures could bring a paradigm shift to the field of orthopedic and craniofacial interventions. Recently, we have shown that sodium magnesium phosphate nanocrystals (gel) are osteoinductive, thixotropic colloidal suspension and can be injected through high gauge needles (unpublished work) and therefore can be used for minimal invasive interventions. In this study, we investigated how this gel can control the release of local anesthetic (mepivacaine) in-vitro and in-vivo with the ultimate goal of developing an injectable bone regeneration biomaterial with analgesic property. Materials and Methods: The gel was prepared by dissolving 85 mg of Mg(OH)2 in 2.2 mL of H3PO4 1.5 M and subsequent addition of 3.8 mL of NaOH 1.5 M under vigorous stirring. The resulting colloidal suspension was centrifuged, and the supernatant was discarded. Different concentrations of mepivacaine were dissolved in the gel for drug release by placing them in Pur-L-Lyzer dialysis kit, incubated in 30mL of PBS at 37Co. The PBS was changed and analyzed with UV-Vis spectroscopy at different time points (0-168) hours in order calculate the amount of drug released. The analgesic action of the mepivacaine with gel was assessed in-vivo using the mouse-hindpaw-model. Twelve mice were assigned into four groups (n=3, each); saline, mepivacaine, gel and gel+mepivacaine. Each mouse received a single injection of the assigned treatment (5 μL subcutaneously) into the planter surface of the hindpaw. Sensitivity to thermal stimuli was tested using radiant heat at different time points (15-120 minutes). Results and Discussions: The gel was able to control the release of mepivacaine for up to 24 hours. Higuchi and Korsmeyer-Peppas models indicated that mepivacaine was release by diffusion. The mepivacaine released by the gel presented no change in its molecular structure as shown by UV-Vis spectra, indicating that the drug was compatible the gel (figure 1). Radiant heat test showed that the gel loaded with mepivacaine provides analgesia and the analgesic action of mepivacaine was prolonged by the gel (figure 2). Conclusion: The bone regeneration biomaterial described here can be injected through high gauge needle and provide analgesia. This biomaterial could minimize the invasiveness of bone regeneration procedures, shorten the healing period and mobilization time while eliminating the need for systemic drugs for pain management. McGill University, Faculty of Dentistry; University of Dammam, College of Dentistry; Saudi Arabian Cultural Bureau

Effect of local anesthetic concentration, dose and volume on the duration of single-injection ultrasound-guided axillary brachial plexus block with mepivacaine: a randomized controlled trial.

BackgroundIn what way volume, concentration and dose affect block duration is controversial. The purpose of the present study is to investigate the effect of dose, volume and concentration of mepivacaine on the duration of sensory and motor blockade in ultrasound-guided single shot axillary brachial plexus blockade.MethodsIn this parallel group randomized trial conducted in the Sint Maartenskliniek Nijmegen, 45 adult patients undergoing minor orthopaedic forearm, wrist or hand surgery were randomized to 3 groups. Group A: 20 mL mepivacaine 1.5 %, Group B: 30 mL mepivacaine 1 % and Group C: 30 mL mepivacaine 1.5 %. Randomization was computer-generated, with allocation concealment by opaque sequentially numbered sealed envelopes. Patients and observers were blinded to group allocation. Primary outcome measure: duration of sensory block.ResultsForty-five patients were randomized, four patients were excluded and replaced, and 15 patients in each group were included in the analysis. Mean (95 % CI) sensory and motor block duration was 256 (230–282) and 254 (226–282) minutes in Group A, 226 (209–243) and 220 (200–240) minutes in Group B and 270 (249–291) and 264 (244–284) minutes in Group C. Duration of sensory and motor block duration differed significantly between groups (p = 0.012 and p = 0.016 respectively). Post-hoc analysis showed a significantly reduced sensory and motor block duration in Group B when compared to Group C of 44 min. No local anesthetic systemic toxicity was reported.ConclusionsWhen using mepivacaine for axillary brachial plexus block, a higher dose and concentration was associated with a longer duration of sensory and motor blockade, but not a higher volume.Trial RegistrationThe Netherlands National Trial Register NTR3648. Registered October 3, 2012.

The effect of mepivacaine on swine lingual, pulmonary and coronary arteries.

BackgroundAlthough mepivacaine has a known biphasic action on the aortic and coronary artery in several animal species, its effects on the lingual and pulmonary artery are not well understood and it is not yet known whether mepivacaine produces vasoconstriction in these vessels. The present study aims to investigate the direct effects of mepivacaine on swine lingual, pulmonary and coronary arterial endothelium-denuded rings.MethodsArtery rings were perfused with isotonic 40 mM KCl until a stable constricted plateau was reached. The rings were then perfused with isotonic 40 mM KCl plus a particular concentration of mepivacaine (0.4 μM, 4.0 μM, 40 μM, 0.4 mM and 4.0 mM). The isometric tension strengths in each experiment were normalized to the strength of the isometric tension immediately before mepivacaine perfusion and expressed as a percentage.ResultsMepivacaine at 0.4 to 40 μM did not significantly alter 40 mM KCl-induced contraction in the lingual, pulmonary and coronary arterial rings. In contrast, mepivacaine at 4 mM produced attenuated vasoconstriction in the lingual, pulmonary and coronary arterial compared with isotonic 40 mM KCl.ConclusionsMepivacaine produced vasoconstriction at lower concentrations, followed by attenuated vasoconstriction at higher concentrations on swine lingual, pulmonary and coronary arterial endothelium-denuded rings. Mepivacaine (4 μM) appeared to increase isotonic 40 mM KCl-induced contraction, followed by attenuated vasoconstriction at 4 mM. Dentists using 3 % mepivacaine should take into consideration that the risk of complications may be increased if more than six mepivacaine cartridges are used in dental treatment or minor surgery, or if over 15 ml of mepivacaine is administered to a patient with cardiovascular complications during general anesthesia for oral maxillofacial surgery.

Local anesthetic cytotoxicity on human mesenchymal stem cells during chondrogenic differentiation.

This study was to investigate the cytotoxic potency of local anesthetics on human mesenchymal stem cells during chondrogenesis. Aggregates were created from density-gradient centrifugation-separated bone marrow-derived mesenchymal stem cells. After 7, 14, and 21days, aggregates were analyzed histologically and immunohistochemically and exposed to equipotent concentrations of bupivacaine, ropivacaine, and mepivacaine for 1h. Cell viability, apoptosis, and necrosis were determined using live-dead and caspase staining. Additionally, following a 1-h exposure on day 7, aggregates were cultured under chondrogenic conditions until day 21 to assess the effects of local anesthetics on differentiation potency of mesenchymal stem cells. In the course of chondrogenesis, mesenchymal stem cells were embedded in varying amount and structure of cartilage-specific extracellular matrix. Contents of sulfated glycosaminoglycan, type I and II collagen increased from day 7 to day 21. Compared to control, death rates of mesenchymal stem cells were significantly elevated 1day after treatment at 7 and 14days. Four days after exposure, death rates were 13-15% at 7 and 11-17% at 14days. Mesenchymal stem cell viability in aggregates at 21days was unchanged to controls. The width of the superficial aggregate zone containing stem cell necrosis decreased with elongated differentiation time. Apoptosis rates were elevated in the edge regions of aggregates, reaching maximum values 4days after treatment. Local anesthetic exposure on day 7 reduced Collagen II, but not DNA contents in aggregates at 21days. Bupivacaine, ropivacaine, and mepivacaine did not differ in mesenchymal stem cell cytotoxicity in aggregates. Local anesthetic exposure results in cytotoxicity of mesenchymal stem cells undergoing chondrogenesis, especially in superficial layers. Therefore, induced cell damage should be avoided during chondrogenesis of mesenchymal stem cells, particularly early after cartilage repair.

In vivodiffusion characteristics following perineural injection of the deep branch of the lateral plantar nerve with mepivacaine or iohexol in horses

Hindlimb proximal suspensory desmopathy is a common injury of sport horses but diagnosis can be difficult because diagnostic analgesia of the region lacks specificity. Perineural analgesia of the deep branch of the lateral plantar nerve (DBLPN) has been proposed as a more specific method of isolating pain of the proximal aspect of the suspensory ligament but the technique has not been evaluated in vivo. To determine the extent of diffusion of contrast medium and mepivacaine following DBLPN analgesia using a single-needle injection technique and to determine if there is inadvertent involvement of the tarsal sheath and/or tarsometatarsal (TMT) joint using this technique. In vivo experimental study. Perineural injection of the DBLPN was performed in 16 limbs with 3 ml of either mepivacaine hydrochloride or positive contrast medium. Contrast medium-injected limbs were radiographed 5, 15, and 30 min post injection and diffusion characteristics were described. In mepivacaine-injected limbs, synovial fluid from the TMT joint was obtained 10 and 20 min post injection and mepivacaine concentrations were analysed. At 5, 15 and 30 min post injection, the contrast medium extended, on average, 19.6, 20.6 and 21.0 mm proximal and 38.0, 43.5 and 51.9 mm distal to the injection site, respectively. Three of 8 (37.5%) limbs had evidence of contrast medium in the tarsal sheath. Two of 8 (25%) limbs had mepivacaine concentrations within the TMT joint sufficient to produce analgesia (>300 mg/l) at 10 min post injection. Contrast medium diffused further in a distal direction than in a proximal direction. Analgesia of the DBLPN can result in inadvertent involvement of the tarsal sheath and/or TMT joint.

Mepivacaine-induced contraction involves increased calcium sensitization mediated via Rho kinase and protein kinase C in endothelium-denuded rat aorta

Mepivacaine is an aminoamide local anesthetic that produces vasoconstriction in vivo and in vitro. The goals of this in vitro study were to determine whether mepivacaine-induced contraction involves calcium sensitization in isolated endothelium-denuded aortas, and to investigate the specific protein kinases involved. The effects of mepivacaine and potassium chloride on intracellular calcium concentrations ([Ca2+]i) and tension in the presence or absence of Y-27632 or GF 109203X were measured simultaneously using the acetoxymethyl ester of fura-2-loaded aortic strips. Cumulative mepivacaine concentration–response curves were generated in the presence or absence of the following inhibitors: Rho kinase inhibitor Y-27632, protein kinase C (PKC) inhibitor GF 109203X, extracellular signal-regulated kinase (ERK) inhibitor PD 98059, c-Jun NH2-terminal kinase (JNK) inhibitor SP600125, and p38 mitogen-activated protein kinase (MAPK) inhibitor SB 203580. Phosphorylation of PKC and MAPK, and membrane translocation of Rho kinase were detected in vascular smooth muscle cells by Western blotting. The slope of the mepivacaine-induced [Ca2+]i-tension curve was higher than that of the KCl-induced [Ca2+]i-tension curve. Pretreatment with Y-27632 or GF 109203X shifted the mepivacaine-induced [Ca2+]i-tension curve to the lower right. Pretreatment with Y-27632, GF 109203X, PD 98059, or SP600125 attenuated mepivacaine-induced contraction in a concentration-dependent manner. Y-27632 and GF 109203X attenuated mepivacaine-induced Rho kinase membrane translocation and PKC phosphorylation, respectively. PD 98059 and SP600125 attenuated mepivacaine-induced ERK and JNK phosphorylation, respectively. Taken together, these results indicate that mepivacaine-induced contraction involves increased calcium sensitization mediated by Rho kinase and PKC. Such contraction mainly involves activation of ERK- and JNK-mediated pathways.

Cytotoxicity of Local Anesthetics on Human Mesenchymal Stem Cells in Vitro

The purpose of this study was to investigate the cytotoxic potency of local anesthetics on human mesenchymal stem cells (MSCs) before and after chondrogenic differentiation. MSCs were exposed to equal and equipotent concentrations of bupivacaine, ropivacaine, and mepivacaine for 1 hour. Cell viability, apoptosis, and necrosis were determined using flow cytometry and live/dead staining. After chondrogenic differentiation, MSC viability was determined in aggregates exposed to equipotent concentrations of the named agents, applying fluorescence microscopy. All local anesthetics showed detrimental cytotoxic effects on MSC monolayer cultures in a concentration- and time-specific manner. Minimum viability rates were found 96 hours after a 1-hour exposure. Bupivacaine 0.5% caused a reduction of vital MSCs to 5% ± 1%. Sixteen percent ± 2% viable cells were detected after treatment with 0.75% ropivacaine. Exposure to 2% mepivacaine decreased vitality rates to 1% ± 0%. Ropivacaine was significantly less cytotoxic than were bupivacaine and mepivacaine. Immediate cell death was mainly caused by necrosis followed by apoptosis afterward. Viability rates of MSCs embedded in cartilaginous tissue after chondrogenic differentiation were not reduced by local anesthetic treatment. Local anesthetics are cytotoxic to MSCs in a concentration-, time-, and agent-dependent manner in monolayer cultures but not in whole-tissue probes. MSCs are applied for treatment of cartilage defects. Intra-articular application of local anesthesia is a common procedure in pain management and has shown chondrotoxic effects. Therefore, it is crucial to evaluate the impact of local anesthetics on human MSCs and regenerative cartilage tissue engineering.

The Cytotoxicity of Bupivacaine, Ropivacaine, and Mepivacaine on Human Chondrocytes and Cartilage

Intraarticular injections of local anesthetics are frequently used as part of multimodal pain regimens. However, recent data suggest that local anesthetics affect chondrocyte viability. In this study, we assessed the chondrotoxic effects of mepivacaine, ropivacaine, and bupivacaine. We hypothesized that specific cytotoxic potencies directly correlate with analgesic potencies, and that cytotoxic effects in intact cartilage are different than in osteoarthritic tissue. Human articular chondrocytes were exposed to equal and equipotent concentrations of bupivacaine, ropivacaine, and mepivacaine for 1 hour. Cell viability, apoptosis, and necrosis were determined at predefined time points using flow cytometry, live-dead staining, and caspase detection. Intact and osteoarthritic human cartilage explants were treated with equipotent concentrations of named drugs to determine cell viability applying fluorescence microscopy. Chondrotoxic effects increased from ropivacaine to mepivacaine to bupivacaine in a time-dependent and concentration-dependent manner. Compared with control, bupivacaine 0.5% decreased chondrocyte viability to 78% ± 9% (P = 0.0183) 1 hour and 16% ± 10% (P < 0.0001) 24 hours later, as determined by live-dead staining in monolayer cultures. Viability rates were reduced to 80% ± 7% (P = 0.0475) 1 hour and 80% ± 10% (P = 0.0095) 24 hours after treatment with ropivacaine 0.75%. After exposure to mepivacaine 2%, viable cells were scored 36% ± 6% (P < 0.0001) after 1 hour and 30% ± 11% (P < 0.0001) after 24 hours. Ropivacaine treatment was less chondrotoxic than bupivacaine (P = 0.0006) and mepivacaine exposure (P = 0.0059). Exposure to concentrations up to 0.25% of bupivacaine, 0.5% of ropivacaine, and 0.5% of mepivacaine did not reveal significant chondrotoxicity in flow cytometry. However, chondrotoxicity did not correlate with potency of local anesthetics. Immediate cell death was mainly due to necrosis followed by apoptosis. Cellular death rates were clearly higher in osteoarthritic compared with intact cartilage after bupivacaine, mepivacaine, and ropivacaine treatment in a decreasing order. Bupivacaine, ropivacaine, and mepivacaine are chondrotoxic in a time-dependent, concentration-dependent, and drug-dependent manner. Chondrotoxic and analgesic potencies do not directly correlate. Cellular death rates were higher in osteoarthritic compared with intact cartilage after local anesthetic treatment.

Discriminative sensory characteristics of the lateral femoral cutaneous nerve after mepivacaine-induced block

Background and objectivesUnmyelinated C-fibres comprise the largest group of somatic afferents and have demonstrated a crucial role not only in the perception of high-threshold mechanically, thermally or chemically induced pain, but also in non-harmful low-threshold mechanical stimuli [1,2]. The objective of our study was to characterize differential sensitivity changes of C-fibre related subclasses of high-threshold and low-threshold polymodal nociceptors and low-threshold mechanoreceptors to the local anaesthetic (LA) mepivacaine during nerve block of the purely sensory lateral femoral cutaneous nerve (LFCN) in human. We assumed a diverse response of different classes of afferents to the two different concentrations of the LA mepivacaine (Scandicaine). MethodsIn a double-blind randomized experimental setting, an ultrasound-guided nerve block of the LFCN was performed in 10 healthy male subjects, each with two different concentrations of mepivacaine (0.5 and 1%). Responsiveness of afferent nerve fibres to different noxious and non-noxious stimuli was tested by Quantitative Sensory Testing (QST) 30, 180, and 300min after nerve block. Both LA concentrations of mepivacaine were compared for time course of the areas of anaesthesia for the tested sensory modalities. ResultsInitial extension of anaesthetic areas at 30min did not differ between both LA concentrations. At 180min only the anaesthetic areas to nociceptive stimuli were reduced at the site of lower mepivacaine injection (260mN: 204mm2 (18; 244; median difference and 95% confidence interval; p<0.05), heat: 276mm2 (3; 305)). In contrast, no significant differences were found between the two concentration when non-nociceptive stimuli were used (100mN: 187mm2 (4; 240), p>0.05, brush: 159mm2 (−59; 202)). ConclusionEqual initial sizes of anaesthesia areas for all sensory modalities can be explained by supramaximal perineural LA molecule concentration in both administered mepivacaine dosages. Upon washout of the LA nociceptive function is restored faster as compared to non-nociceptive sensation and higher concentration of the LA are required to maintain the analgesia. Quantitative sensory testing is able to detect different susceptibility of low threshold mechanosensors and subtypes of nociceptive C-fibres to mepivacaine. Using painful mechanical, heat and electrical stimulation different classes of nociceptors will be activated. The analgesic areas to electrical stimulation were particularly small; one might therefore hypothesize that the proposed protocol allows to also differentiate mechano-insensitive (“silent”) and mechanosensitive (“polymodal”) nociceptors. ImplicationsQST is a non-invasive method to functionally examine sensory modalities and their pharmacological modulation in humans. The method is sufficiently sensitive to differentiate the analgesic properties of mepivacaine at 0.5 and 1% and might also be adequate to different classes of nociceptors. Further development of nociceptive stimuli including supra-threshold encoding characteristics will enable to investigate peripheral analgesic effects more specifically and thus might help to design new analgesics with preferential effect on high frequency discharge of nociceptors.

Mepivacaine-induced contraction involves phosphorylation of extracellular signal-regulated kinase through activation of the lipoxygenase pathway in isolated rat aortic smooth muscle

Mepivacaine is an aminoamide local anesthetic with an intermediate duration that intrinsically produces vasoconstriction both in vivo and in vitro. This study investigated the arachidonic acid metabolic pathways involved in mepivacaine-induced contraction, and elucidated the associated cellular mechanism with a particular focus on extracellular signal-regulated kinase (ERK) in endothelium-denuded rat aorta. Isolated rat thoracic aortic rings were suspended for isometric tension recording. Cumulative mepivacaine concentration-response curves were generated in the presence or absence of the following inhibitors: quinacrine dihydrochloride, nordihydroguaiaretic acid, phenidone, AA-861, indomethacin, NS-398, SC-560, fluconazole, PD 98059, and verapamil. Mepivacaine-induced ERK phosphorylation, 5-lipoxygenase (5-LOX) expression, and cyclooxygenase (COX)-2 expression in rat aortic smooth muscle cells were detected by Western blot analysis in the presence or absence of inhibitors. Mepivacaine produced tonic contraction in isolated endothelium-denuded rat aorta. Quinacrine dihydrochloride, nordihydroguaiaretic acid, phenidone, AA-861, NS-398, PD 98059, and verapamil attenuated mepivacaine-induced contraction in a concentration-dependent manner. However, fluconazole had no effect on mepivacaine-induced contraction. PD 98059, quinacrine dihydrochloride, nordihydroguaiaretic acid, AA-861, phenidone, and indomethacin attenuated mepivacaine-induced ERK phosphorylation. Mepivacaine upregulated 5-LOX and COX-2 expression. These results suggest that mepivacaine-induced contraction involves ERK activation, which is primarily mediated by the 5-LOX pathway and in part by the COX-2 pathway.

Mepivacaine-induced contraction is attenuated by endothelial nitric oxide release in isolated rat aorta

Mepivacaine is an aminoamide-linked local anesthetic with an intermediate duration that intrinsically produces vasoconstriction both in vivo and in vitro. The aims of this in-vitro study were to examine the direct effect of mepivacaine in isolated rat aortic rings and to determine the associated cellular mechanism with a particular focus on endothelium-derived vasodilators, which modulate vascular tone. In the aortic rings with or without endothelium, cumulative mepivacaine concentration-response curves were generated in the presence or absence of the following antagonists: N(ω)-nitro-L-arginine methyl ester [L-NAME], indomethacin, fluconazole, methylene blue, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one [ODQ], verapamil, and calcium-free Krebs solution. Mepivacaine produced vasoconstriction at low concentrations (1 × 10(-3) and 3 × 10(-3) mol/L) followed by vasodilation at a high concentration (1 × 10(-2) mol/L). The mepivacaine-induced contraction was higher in endothelium-denuded aortae than in endothelium-intact aortae. Pretreatment with L-NAME, ODQ, and methylene blue enhanced mepivacaine-induced contraction in the endothelium-intact rings, whereas fluconazole had no effect. Indomethacin slightly attenuated mepivacaine-induced contraction, whereas verapamil and calcium-free Krebs solution more strongly attenuated this contraction. The vasoconstriction induced by mepivacaine is attenuated mainly by the endothelial nitric oxide - cyclic guanosine monophosphate pathway. In addition, mepivacaine-induced contraction involves cyclooxygenase pathway activation and extracellular calcium influx via voltage-operated calcium channels.