scholarly journals EFFECT OF THE POLARIZATION OF TRIPOLAR ELECTRODES ON ELECTRICAL NERVE BLOCK IN-VIVO

2018 ◽  
Author(s):  
Büşra Şahin ◽  
Betül Erol ◽  
Zafer Soybaş ◽  
Sefa Şimşek ◽  
Rohat Melik
Keyword(s):  
Nerve Block

Structure-Activity Relation of N-alkyl Tetracaine Derivatives as Neurolytic Agents for Sciatic Nerve Lesions 

1998 ◽  
Vol 88 (2) ◽  
pp. 417-428 ◽  
Author(s):  
Ging Kuo Wang ◽  
Marina Vladimirov ◽  
Hao Shi ◽  
Wai Man Mok ◽  
Johann G. Thalhammer ◽  
...  
Keyword(s):  
Sciatic Nerve ◽  
Nerve Block ◽  
Local Anesthetic ◽  
Drug Application ◽  
Rapid Onset ◽  
Na Channel ◽  
Channel Blockers ◽  
Sciatic Notch ◽  
Structure Activity

Background N-butyl tetracaine has local anesthetic and neurolytic properties. An injection of this drug at the rat sciatic notch produces rapid onset and nerve impairment lasting > 1 week. This study aimed to elucidate the structure-activity relation of various tetracaine derivatives to design better neurolytic agents. Methods N-alkyl tetracaine salts (n = 2-6) were synthesized, and their ability to elicit sciatic nerve impairment of sensory and motor functions in vivo was tested in rats. A single dose (0.1 ml at 37 mM) was administered close to the sciatic nerve at the sciatic notch. Regeneration was assessed morphologically in transverse sections of treated nerves. Finally, the drug potency in blocking Na+ currents was studied under voltage-clamp conditions. Results N-ethyl and N-propyl tetracaine derivatives were non-neurolytic and elicited complete sciatic nerve block lasting 3-7 h. In contrast, N-butyl, N-pentyl, and N-hexyl tetracaine derivatives were strong neurolytic agents and elicited functional impairment of sciatic nerve for > 1 week. All derivatives were strong Na+ channel blockers, more potent than tetracaine if applied intracellularly. External drug application showed marked differences in their wash-in rate: tetracaine > N-hexyl > N-butyl > N-ethyl tetracaine. All derivatives were trapped within the cytoplasm and showed little washout within 7 min. Conclusions When n-alkylation is 4-6, n-alkyl tetracaine appeared as a strong neurolytic agent. Neurolytic derivatives retained their local anesthetic activity and elicited rapid onset of nerve block after injection. Such derivatives are potential local anesthetic-neurolytic dual agents for chemical lesions of the sciatic nerve.

Greater occipital nerve block modulates nociceptive signals within the trigeminocervical complex

2021 ◽  
pp. jnnp-2021-326433
Author(s):  
Jan Hoffmann ◽  
Jan Mehnert ◽  
Elena M Koo ◽  
Arne May
Keyword(s):  
Nerve Block ◽  
Clinical Effects ◽  
Double Blind ◽  
Occipital Nerve ◽  
Randomised Study ◽  
In Vivo Experiments ◽  
Greater Occipital Nerve Block ◽  
Greater Occipital Nerve ◽  
Occipital Nerve Block

IntroductionThe pharmacological block of the greater occipital nerve has been proven effective in numerous headache and facial pain syndromes. This clinical effect supports the hypothesis of a strong functional interaction between the occipital and trigeminal nerves which has been proposed in neurophysiological in vivo experiments in rodents. Although it is likely that the interaction has to occur in the central nervous system, the exact site and the mechanisms of the interaction remain largely unknown.MethodsFocusing on these questions we investigated in a double-blind, placebo-controlled, randomised study the influence of an occipital nerve block with lidocaine 1% on neuronal activation in the trigeminocervical complex using high-resolution functional magnetic resonance on a 3T scanner. In order to investigate potential clinical effects on the trigeminal nerve, we further performed quantitative sensory testing and analysed a potential shift in thermal detection and pain thresholds.ResultsThe pharmacological block of the greater occipital nerve induced an occipital anaesthesia ipsilateral to the block. Functional imaging revealed that the occipital injection of lidocaine but not placebo significantly reduced nociceptive trigeminal activation.ConclusionsThese data suggest that the functional inhibition of the occipital nerve block on trigeminal nociceptive activity is likely to occur at the C2 level where the occipital nerve enters the trigeminocervical complex and converges on the same central nuclei before the signal crosses the midline at that level and is then transmitted to higher processing centres.

scholarly journals Ultralong Peripheral Nerve Block by Lidocaine:Prilocaine 1:1 Mixture in a Lipid Depot Formulation

2006 ◽  
Vol 104 (1) ◽  
pp. 110-121 ◽  
Author(s):  
Lars Söderberg ◽  
Henrik Dyhre ◽  
Bodil Roth ◽  
Sven Björkman
Keyword(s):  
Sciatic Nerve ◽  
Nerve Block ◽  
Local Anesthetic ◽  
In Vitro Release ◽  
Sciatic Nerve Block ◽  
Depot Formulation ◽  
Duration Of Action ◽  
Depot Preparations

Background The aim of this study was to develop stable and easily injectable lipid depot preparations of local anesthetics in which the drug concentration can be varied according to desired duration of action. Methods The formulations contained a 2.0, 5.0, 10, 20, 40, 60, 80, or 100% eutectic mixture of lidocaine and prilocaine base in medium-chain triglyceride. Duration of sciatic nerve block and local neurotoxicity was investigated in rats with 2.0% lidocaine:prilocaine HCl solution and 99.5% ethanol as controls. The rate of release of local anesthetic from the site of administration and the possibility to predict in vivo depot characteristics from in vitro release data were investigated for the 20 and 60% formulations. Results The duration of sensory sciatic block was prolonged 3 times with the 20% formulation and approximately 180 times with the 60% formulation, in comparison with the 2% aqueous solution. With the 80 and 100% formulations, all animals still showed nerve block after 2 weeks. The in vivo release of local anesthetic could be approximately predicted from in vitro data for the 20% but not for the 60% formulation. The formulations of 60% or greater and ethanol showed neurotoxic effects. Conclusions The pharmaceutical properties of these formulations compare favorably with those of other depot preparations. The high-percentage ones showed the longest duration of action yet reported for sciatic nerve block in rats. The possibility of using a high-concentration local anesthetic depot formulation as an alternative to ethanol or phenol for long-term nerve blocks in chronic pain merits further investigation.

scholarly journals Effect of experimental suprascapular nerve block on active glenohumeral translations in vivo

2006 ◽  
Vol 24 (3) ◽  
pp. 491-500 ◽  
Author(s):  
Clément M. L. Werner ◽  
Dominik Weishaupt ◽  
Stephan Blumenthal ◽  
Armin Curt ◽  
Philippe Favre ◽  
...  
Keyword(s):  
Nerve Block ◽  
Suprascapular Nerve ◽  
Suprascapular Nerve Block

Potency of Bupivacaine Stereoisomers Tested  In Vitro and  In Vivo

2000 ◽  
Vol 93 (3) ◽  
pp. 744-755 ◽  
Author(s):  
Marina Vladimirov ◽  
Carla Nau ◽  
Wai Man Mok ◽  
Gary Strichartz
Keyword(s):  
Sciatic Nerve ◽  
Nerve Block ◽  
Local Anesthetics ◽  
Neuroendocrine Cells ◽  
Primary Role ◽  
Na Channels ◽  
Rat Sciatic Nerve ◽  
Na Currents

Background Chiral local anesthetics, such as ropivacaine and levobupivacaine, have the potential advantage over racemic mixtures in showing reduced toxic side effects. However, these S-(levo, or "-")isomers also have reportedly lower potency than their optical antipode, possibly resulting in no advantage in therapeutic index. Potency for local anesthetics inhibiting Na+ channels or action potentials depends on the pattern of membrane potential and so also does the stereopotency ratio. Here the authors have quantitated the stereopotencies of R-, S-, and racemic bupivacaine, comparing several in vitro assays of neuronal Na+ channels with those from in vivo functional nerve block, to establish relative potencies and to understand better the role of different modes of channel inhibition in overall functional anesthesia. Methods The binding of bupivacaine to Na+ channels was assessed indirectly by its antagonism of [3H]-batrachotoxin binding to rat brain synaptosomes. Inhibition of Na+ currents by bupivacaine was directly assayed in voltage-clamped GH-3 neuroendocrine cells. Neurobehavioral functions were disrupted by bupivacaine percutaneously injected (0.1 ml; 0.0625-1.0%) at the rat sciatic nerve and semiquantitatively assayed. Concentration-dependent actions of R-, S-, and racemic bupivacaine were compared for their magnitude and duration of action. Results Competitive batrachotoxin displacement has a stereopotency ratio of R:S = 3:1. Inhibition of Na+ currents with different prepulse potentials shows that S > R potency when the membrane is hyperpolarized, and R > S potency when it is depolarized from normal resting values. Functional deficits assayed in vivo usually demonstrate no consistent enantioselectivity and only a modest stereopotency (R:S = 1.2-1.3) for peak analgesia achieved at the lowest doses. Other functions display no significant stereopotency in either the degree, the duration, or their product (area under the curve) at any dose. Conclusion Although the in vitro actions of bupivacaine showed stereoselectivity ratios of 1.3-3:1 (R:S), in vivo nerve block at clinically used concentrations showed much smaller ratios for peak effect and no significant enantioselectivity for duration. A primary role for the blockade of resting rather than open or inactivated Na+ channels may explain the modest stereoselectivity in vivo, although stereoselective factors controlling local disposition cannot be ruled out. Levo-(S-)bupivacaine is effectively equipotent to R- or racemic bupivacaine in vivo for rat sciatic nerve block.

Clonidine Prolongation of Lidocaine Analgesia after Sciatic Nerve Block in Rats Is Mediated via the Hyperpolarization-activated Cation Current, Not by α-Adrenoreceptors

2004 ◽  
Vol 101 (2) ◽  
pp. 488-494 ◽  
Author(s):  
Jeffrey S. Kroin ◽  
Asokumar Buvanendran ◽  
Daniel R. Beck ◽  
Julie E. Topic ◽  
Daniel E. Watts ◽  
...  
Keyword(s):  
Nerve Block ◽  
Sensory Block ◽  
Sprague Dawley ◽  
Sensory Blockade ◽  
Alpha Adrenergic Receptors ◽  
Cation Current ◽  
Adrenergic Antagonist ◽  
Zd 7288

Background Although clonidine is commonly combined with local anesthetics to extend duration of peripheral nerve block, the mechanism by which clonidine potentiates local anesthetic action in vivo is unclear. Methods Male Sprague-Dawley rats received percutaneous injections of 1% lidocaine with/without clonidine or epinephrine into the sciatic notch and duration of sensory blockade was quantified by inhibition of pinprick foot withdrawal. The antagonists prazosin or yohimbine were injected before lidocaine with clonidine or epinephrine to determine the role of alpha-adrenergic receptors. The role of the hyperpolarization-activated cation current (Ih) was evaluated by injecting the current blocker ZD 7288 as well as the current enhancers forskolin and 8-Br-cAMP before lidocaine alone or with 15 micrograms/ml clonidine. Results Mean duration of sensory block for lidocaine alone was 69 +/- 2 min. Sensory block duration increased monotonically with increasing doses of added clonidine or epinephrine. Preinjection of prazosin but not yohimbine prevented the increase in block duration seen with epinephrine. Neither alpha-adrenergic antagonist attenuated the extended duration of block with clonidine. ZD 7288 extended sensory blockade equivalent to the prolongation observed with clonidine. There was no additive effect when ZD 7288 and clonidine were combined, and a decreased duration of nerve block when either forskolin or 8-Br-cAMP preceded injection of lidocaine with clonidine. Conclusions The findings indicate that prolongation of duration of in vivo lidocaine nerve blockade by clonidine is not mediated by an alpha-adrenergic mechanism but likely involves the Ih current.

Effect of Epinephrine on Lidocaine Clearance In Vivo 

1999 ◽  
Vol 91 (4) ◽  
pp. 962-962 ◽  
Author(s):  
Christopher M. Bernards ◽  
Dan J. Kopacz
Keyword(s):  
Blood Flow ◽  
Nerve Block ◽  
Local Anesthetic ◽  
Adrenergic Receptor ◽  
Receptor Agonist ◽  
Peroneal Nerve ◽  
Sensory Block ◽  
Compartment Model ◽  
Adrenergic Receptor Agonist

Background Local anesthetic nerve block prolonged by epinephrine is thought to result from local vasoconstriction and consequent decreased local anesthetic clearance from the injection site. However, no study has yet confirmed this directly in humans by measuring tissue concentrations of local anesthetic over time. In addition, recent studies have shown that the alpha2-adrenergic receptor agonist, clonidine, also prolongs nerve block without altering local anesthetic clearance. Because epinephrine is also an alpha2-adrenergic receptor agonist, it is possible that epinephrine prolongs local anesthetic block by a pharmacodynamic mechanism and not a pharmacokinetic one. This study was designed to address this issue. Methods Microdialysis probes were placed adjacent to the superficial peroneal nerve in both feet of eight volunteers. Plain lidocaine (1%) was injected along one peroneal nerve and lidocaine with epinephrine (2.5 microg/ml) was injected along the other nerve in a double-blinded, randomized manner. The concentration of lidocaine in tissue was measured at 5-min intervals, and sensory block and cutaneous blood flow were assessed by laser Doppler at 10-min intervals for 5 h. The resulting data for lidocaine concentration versus time were fit to a two-compartment model using modeling software. Results Epinephrine prolonged sensory block by decreasing local blood flow and slowing clearance. There was no evidence of a pharmacodynamic effect of epinephrine. Conclusion Although epinephrine activates alpha2-adrenergic receptors, its mechanism for prolonging the duration of local anesthetic block rests on its ability to decrease local anesthetic clearance and not on a pharmacodynamically mediated potentiation of local anesthetic effect.

scholarly journals An in vivo study comparing efficacy of 0.25% and 0.5% bupivacaine in infraorbital nerve block for postoperative analgesia

2019 ◽  
Vol 19 (4) ◽  
pp. 209
Author(s):  
Aditi Saha ◽  
Sonal Shah ◽  
Pushkar Waknis ◽  
Sharvika Aher ◽  
Prathamesh Bhujbal ◽  
...  
Keyword(s):  
Nerve Block ◽  
Postoperative Analgesia ◽  
Infraorbital Nerve ◽  
In Vivo Study

scholarly journals A comparative evaluation of anesthetic efficacy of articaine 4% and lidocaine 2% with anterior middle superior alveolar nerve block and infraorbital nerve block: An in vivo study

2016 ◽  
Vol 19 (6) ◽  
pp. 527 ◽  
Author(s):  
SumaPrahlad Saraf ◽  
PrahladAnnappa Saraf ◽  
Laxmikant Kamatagi ◽  
Santosh Hugar ◽  
Shridevi Tamgond ◽  
...  
Keyword(s):  
Nerve Block ◽  
Comparative Evaluation ◽  
Infraorbital Nerve ◽  
In Vivo Study

scholarly journals Lido-OH, a Hydroxyl Derivative of Lidocaine, Produced a Similar Local Anesthesia Profile as Lidocaine With Reduced Systemic Toxicities

2021 ◽  
Vol 12 ◽  
Author(s):  
Qinqin Yin ◽  
Weiyi Zhang ◽  
Bowen Ke ◽  
Jin Liu ◽  
Wensheng Zhang
Keyword(s):  
Sciatic Nerve ◽  
Local Anesthesia ◽  
Nerve Block ◽  
Therapeutic Index ◽  
Negative Control ◽  
Sciatic Nerve Block ◽  
Dose Effect ◽  
Effective Doses ◽  
Block Models

Background: lidocaine is one of the most commonly used local anesthetics for the treatment of pain and arrhythmia. However, it could cause systemic toxicities when plasma concentration is raised. To reduce lidocaine’s toxicity, we designed a hydroxyl derivative of lidocaine (lido-OH), and its local anesthesia effects and systemic toxicity in vivo were quantitively investigated.Method: the effectiveness for lido-OH was studied using mouse tail nerve block, rat dorsal subcutaneous infiltration, and rat sciatic nerve block models. The systemic toxicities for lido-OH were evaluated with altered state of consciousness (ASC), arrhythmia, and death in mice. Lidocaine and saline were used as positive and negative control, respectively. The dose-effect relationships were analyzed.Results: the half effective-concentration for lido-OH were 2.1 mg/ml with 95% confident interval (CI95) 1.6–3.1 (lidocaine: 3.1 mg/ml with CI95 2.6–4.3) in tail nerve block, 8.2 mg/ml with CI95 8.0–9.4 (lidocaine: 6.9 mg/ml, CI95 6.8–7.1) in sciatic nerve block, and 5.9 mg/ml with CI95 5.8–6.0 (lidocaine: 3.1 mg/ml, CI95 2.4–4.0) in dorsal subcutaneous anesthesia, respectively. The magnitude and duration of lido-OH were similar with lidocaine. The half effective doses (ED50) of lido-OH for ACS was 45.4 mg/kg with CI95 41.6–48.3 (lidocaine: 3.1 mg/kg, CI95 1.9–2.9), for arrhythmia was 16.0 mg/kg with CI95 15.4–16.8 (lidocaine: 3.0 mg/kg, CI95 2.7–3.3), and for death was 99.4 mg/kg with CI95 75.7–124.1 (lidocaine: 23.1 mg/kg, CI95 22.8–23.4). The therapeutic index for lido-OH and lidocaine were 35.5 and 5.6, respectively.Conclusion: compared with lidocaine, lido-OH produced local anesthesia at similar potency and efficacy, but with significantly reduced systemic toxicities.

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