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Results for “ANESTHETICS, LOCAL”

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PubMed1990

[Local anesthetics in the aqueous humor in local anesthesia of the eye].

Local anesthetics injected retrobulbarly are detectable in the aqueous humor. From 40 patients who received a total dose of 140 mg lidocaine, 15 mg bupivacaine, and 30 mg etidocaine, samples of aqueous humor were taken between 30 and 90 minutes after administration (average 57 minutes). The mean lidocaine concentration was 1.02 micrograms/ml, that of bupivacaine 0.075 micrograms/ml. Etidocaine, used only for facial nerve block in front of the ear, could not be detected in the aqueous humor. All three substances were found in the central venous blood. It therefore appears unlikely that any of them are transported via the blood-aqueous barrier, whether actively or passively. Local anesthetics can inhibit corneal cell proliferation and result in lens opacification when administered into the conjunctival sac. It may be that local anesthetics detected in the aqueous humor have similar effects resulting from contact with the cornea and lens.

Aged↗
PubMed1994

Local anesthetics as adjuvant analgesics.

Local anesthetics administered to block nerve conduction for surgical anesthesia and to provide analgesia in management of acute pain have become a standard of anesthesiology practice. These drugs have had an important role in the multimodality management of chronic pain as well, and this role is expanding since the revival of systemic administration. Local anesthetics are analgesics, albeit not in the traditional clinical and pharmacologic sense. Evidence suggests that intravenous administration is an effective treatment in chronic neuropathic pain syndromes. There is also evidence that intravenous local anesthetics can relieve acute pain. Furthermore, the novel idea that acute procedural and postprocedural pain control with local anesthetics could prevent the development of chronic pain syndromes, including chronic neuropathic pain syndromes, adds another important potential dimension to the role of local anesthetics in pain management.

Adjuvants, Pharmaceutic↗
PubMed1992

Comparison of the efficacy of different local anesthetics and techniques of local anesthesia in therapeutic abortions.

OBJECTIVES: The objectives of this study were to determine whether carbonated or plain lidocaine provides better pain control during abortions and to determine whether deep injections of lidocaine provide better pain control than regular injections of lidocaine. STUDY DESIGN: Phase 1 was a prospective, randomized, double-blind trial comparing 10 cm3 of 2% carbonated lidocaine with plain lidocaine. In phase 2 the plain lidocaine group in phase 1 was compared prospectively with the next group of patients, in whom a new technique of deep injection was used. A pain scale was administered by the counselor after dilatation and at the end of the procedure. RESULTS: The improvement in pain scores with carbonated lidocaine was 8%. The improvement with the deep injection technique was 25%. CONCLUSION: The improvement in pain scores with deep injection was clinically significant and is recommended.

Abortion, Induced↗
PubMed2002

Influence of anesthetic flow rate delivered by the Wand Local Anesthetic System on pain response to palatal injections.

PURPOSE: To compare pain response between two different flow rates (slow versus fast) of local anesthetic solution injected into palatal tissue using the recently available Wand Local Anesthetic System (WLAS), which provides the technologic advance to permit reliable replication of constant injection flow rates, regardless of tissue resistance. METHODS AND MATERIALS: Twenty adult subjects received bilateral palatal injections of local anesthetic in random sequence during the same appointment following topical anesthesia application. Pain response was measured by subjective self-report using a visual analogue scale, a quantified verbal descriptor scale, and a comparison to prior injection experience, as well as an operator's global assessment of the subject's pain response. Heart rate, as a physiologic indicator of pain response, was also recorded. RESULTS: All measurements of pain response were statistically less for the slow compared to the fast injection rate. No significant difference in mean heart rate, however, was demonstrated between the two flow rates. A slow, constant flow rate (161 sec/mL) of a 0.3 mL volume of local anesthetic solution was statistically less painful than a fast flow rate (29 sec/mL) during palatal injection. Contrary to the manufacturer's claim, the WLAS reduced but did not eliminate pain elicited by palatal injections in some patients.

Adult↗
PubMed1988

Toxicity of local anesthetic agents.

The toxicity of local anesthetic agents can be divided into two categories: (1) systemic toxic reactions due usually to an accidental intravascular injection and (2) local tissue toxicity. The systemic toxicity of local anesthetic agents is primarily characterized by CNS excitation and convulsive activity. The cardiovascular system is more resistant to the toxic actions of local anesthetics. However, local anesthetics can exert a negative chronotropic and inotropic action and cause profound peripheral vasodilation. The combination of cardiac depression and peripheral vascular dilation results in irreversible circulatory collapse. The more potent agents such as bupivacaine appear to be more cardiotoxic and may precipitate ventricular arrhythmias and ventricular fibrillation. Local tissue toxicity is rare following the administration of local anesthetics. However, large doses of chloroprocaine solutions administered intrathecally have been associated with prolonged sensory-motor deficits in a few patients due probably to the low pH and presence of sodium bisulfite in the chloroprocaine solutions. In general, local anesthetic agents are relatively safe if administered properly. However, as with any pharmacological agents, local anesthetics may cause severe toxic reactions due to the improper use of these drugs.

Akathisia, Drug-Induced↗
PubMed2001

Role of the dopamine transporter and the sodium channel in the cocaine-like discriminative stimulus effects of local anesthetics in rats.

RATIONALE: Local anesthetics bind to the dopamine transporter (DAT), inhibit dopamine (DA) uptake and have been reported to have cocaine-like discriminative stimulus effects. The hypothesis of the present study was that affinity at the DAT and potency as a DA uptake blocker determines potency as a cocaine-like discriminative stimulus among local anesthetics, and maximum DA uptake inhibition determines maximum cocaine-like discriminative stimulus effects. OBJECTIVES: Cocaine-like discriminative potency was compared to DAT affinity and DA uptake inhibition potency, and maximum cocaine-like discriminative stimulus effects were compared to maximum DA uptake inhibition for procaine, chloroprocaine, dimethocaine, tetracaine and lidocaine. METHODS: Discriminative stimulus effects were determined in two groups of rats using 10 mg/kg and 3.0 mg/kg cocaine training doses. DAT affinity and DA uptake inhibition effects were determined in vitro in rat caudate nucleus tissue. Additionally, sodium channel affinity was determined in rat frontal cortex tissue. RESULTS: In the 10 mg/kg group, none of the local anesthetics fully substituted for cocaine and all decreased response rate. Rate decreasing potencies were positively correlated with sodium channel affinities. In the low training dose group, all the local anesthetics except tetracaine substituted fully for cocaine. Discriminative potencies were positively correlated with sodium channel affinities. Maximum DA uptake inhibition did not adequately predict maximum discriminative stimulus effects. CONCLUSIONS: Cocaine-like discriminative stimulus effects of local anesthetics were more prominent at a low than at a high training dose of cocaine. Sodium channels seem to have a direct influence on discriminative effects at low cocaine doses, whereas they have an indirect influence on discriminative effects at high cocaine doses by decreasing response rates.

Anesthetics, Local↗
PubMed2000

The pharmacology of local anesthetics.

The pharmacology of local anesthetics is an integration of the basic physiology of excitable cells and the mechanism by which local anesthetics are capable of interrupting conduction of neural messages. The common characteristics of the molecules with local anesthetic action have been identified and can explain the properties of the agents. These same chemical characteristics also explain toxicity of these agents and differences that exist between local anesthetics with similar structure.

Anesthetics, Local↗
PubMed1989

[Local anesthetic level and cardiovascular changes following local anesthesia in cataract operations with 3% mepivacaine].

Are there toxic plasma levels of mepivacaine after local anesthesia for ophthalmic surgery with 3% mepivacaine? What hemodynamic changes occur during injection of the local anesthetics? Fifteen patients undergoing cataract surgery were given 10 ml of mepivacaine (3%) as a local anesthetic regardless of body weight. After inserting an arterial line, blood samples were taken before the beginning of the injection of mepivacaine and after 3, 5, 10, 15, 30, and 60 min. Concentrations of the drug were measured by gas chromatography. During the first 15 min arterial blood pressure and ECG were registered continuously on a multichannel recorder. The maximum mepivacaine plasma levels were estimated after 15 min with a range from 0.28 to 6.95 micrograms/ml (means +/- SD: 4.5 +/- 1.47 micrograms/ml). The blood pressure was elevated over the preoperative value, at the beginning of the evaluation period, but there was no change in the blood-pressure level over the whole period. In 4 patients without known cardiac arrhythmias, ventricular or supraventricular extrasystoles occurred. The mepivacaine plasma levels complied with resorption kinetics, which is an indication that there were few intravascular injections and that the injection technique war correct. On the other hand, in some patients the mepivacaine plasma levels exceeded the toxic level. Even in ophthalmic surgery, local anesthetics should be given in relation to the body weight of the patients. The high blood-pressure levels indicated non-optimal preoperative treatment of the hypertonic patients, which was followed by an intraoperative exacerbation of the blood pressure.

Aged↗
PubMed1984

Inhibition of binding of [3H]batrachotoxinin A 20-alpha-benzoate to sodium channels by local anesthetics.

The effects of several local anesthetics on the binding of ligands to receptors associated with voltage-sensitive sodium channels in rat brain synaptosomes have been examined. In the presence of 0.3 microM scorpion toxin, the 13 local anesthetics tested inhibited the specific binding of [3H]batrachotoxinin A 20 alpha-benzoate [( 3H]BTX-B), a ligand which binds to a receptor site responsible for the activation of sodium channel ion flux, in a dose-dependent fashion, with KD values ranging from 1.2 microM for tetracaine to 1.58 mM for benzocaine. A plot of log KD from these binding experiments against log K0.5 for inhibition of sodium currents by local anesthetics from electrophysiological experiments yielded a regression line with a slope of 0.84 and a correlation coefficient, r, of 0.86, demonstrating that the inhibition of [3H]BTX-B binding by local anesthetics occurs within a concentration range of physiological relevance. Tetracaine had little effect on basal 125I-labeled scorpion toxin binding to synaptosomes in the absence of batrachotoxin. However, in the presence of batrachotoxin, tetracaine inhibited the batrachotoxin-dependent increase in scorpion toxin binding (KD = 2.0 microM) in a dose-dependent manner, suggesting that inhibition of [3H]BTX-B binding by local anesthetics does not occur through binding at the scorpion toxin binding site. The inhibition of [3H]BTX-B binding by lidocaine was reversible within 30 min when samples were diluted from 10(-3)M to 10(-4) M lidocaine. Scatchard analysis of [3H]BTX-B binding to synaptosomes showed that bupivacaine and tetracaine reduced receptor affinity without decreasing maximal binding capacity. This reduction in receptor affinity in the presence of local anesthetics appears to be due, at least in part, to an increased rate of ligand dissociation from the receptor-ligand complex, suggesting an indirect allosteric mechanism for the inhibition of [3H]BTX-B binding by local anesthetics. Analysis of the effects of local anesthetics in terms of an allosteric model of drug action showed that they bind to inactive states of sodium channels with at least a 10-fold higher affinity than active states. A 7-fold difference in KD for inhibition of [3H]BTX-B binding between the local anesthetic stereoisomers RAC 109 I and RAC 109 II was observed. Similarly, the dissociation rate constant for the [3H]BTX-B/receptor complex was increased 9.3-fold in the presence of RAC 109 II and 4.3-fold in the presence of a comparable concentration of RAC 109 I.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthetics, Local↗
PubMed2002

Application of local anesthetics in dermatologic surgery.

BACKGROUND: Local anesthesia is an integral aspect of cutaneous surgery. Its effects provide a reversible loss of sensation in a limited area of skin, allowing dermatologists to perform diagnostic and therapeutic procedures safely, with minimal discomfort and risk to the patient. OBJECTIVE: This article discusses the application of local anesthetics in dermatologic surgery through a brief review of the mechanism of local anesthetic activity, classification of local anesthetics, and adverse effects. The discussion will focus on the different methods of administration and techniques that may make the administration less painful to patients. METHODS: An evaluation of the literature, as well as clinical experience in the administration of local anesthetics provide the basis for this review. CONCLUSION: Local anesthesia provides a safe and effective means of decreasing patient's sensitivity to pain. Because of its critical importance to the field of dermatology, a working knowledge of local anesthetics is necessary for optimal use of these agents.

Anesthesia, Local↗
PubMed1993

The chemistry and pharmacology of local anesthetics.

The most common local anesthetics in clinical use today are of two classes: amino-esters and amino-amides. These two classes differ not only in their chemical structure but also in regard to their metabolism and allergic potential. Potency, onset of action, duration of action, and relative blockade of sensory and motor fibers are important clinical properties of local anesthetics. These clinical properties are related to the physiochemical properties of lipid solubility, pKa, and protein binding. The effects of local anesthetics are primarily caused by the blockade of the sodium channels, thus affecting the slow and fast depolarization phase of the action potential. With the basic understanding of the chemistry and pharmacology of the different local anesthetic agents, the nurse anesthetist can more effectively integrate the use of these drugs into their clinical practice.

Action Potentials↗
PubMed1979

Alteration of insulin binding and cytoskeletal organization in cultured fibroblasts by tertiary amine local anesthetics.

Tertiary amine local anesthetics cause a time- and dose-dependent, reversible increase in insulin binding sites in cultured chick embryo fibroblasts. Incubation of fibroblasts with 0.2 mM dibucaine for 3 h at 37 degrees C results in a twofold to threefold increase in insulin binding, with an increase in average number of binding sites (Ka = 3.0 X 10(7) M-1) from 9 X 10(3) per cell. Trypsin or ethyleneglycoltetraacetic acid (EGTA) alone increases insulin binding twofold to threefold, but fails to further increase 125I-insulin binding in cells pretreated with dibucaine. Transformation of chick embryo fibroblasts with Rous sarcoma virus causes a threefold to fivefold increase in insulin binding, which is not further increased by incubation with dibucaine. As demonstrated by transmission electron microscopy, dibucaine and trypsin also induce changes in the cytoskeleton of chick embryo fibroblasts, characterized by disorganization and disappearance of microfilament and microtubule bundles. These alterations are accompanied by gross morphologic changes, including rounding of cells and appearance of numerous ruffles and blebs on the cell surface. These observations are consistent with the hypothesis that expression of surface receptors in cultured chick embryo fibroblasts is related to the organization and disorganization of cytoskeletal structures.

Anesthetics, Local↗
PubMed2002

An update on local anesthetics in dentistry.

Local anesthetics are the most commonly used drugs in dentistry. This article provides a brief update on the pharmacology, adverse effects and clinical applications of these drugs, as well as the role of vasoconstrictors.

Action Potentials↗
PubMedDate not supplied

Influence of local anesthetics on ventilation.

Local anesthetics (lidocaine, mepivacaine or bupivacaine) were given as an intravenous infusion to 18 volunteers to study the influence of these drugs on resting ventilation (breathing air) and stimulated ventilation (hypercarbia- or hypoxemia-induced). Control measurements were made of resting ventilation and stimulated ventilation prior to the infusion. The ventilatory measurements were repeated during the latter half of the infusion, when plasma concentrations of these agents were considered to be near steady-state levels (mean plasma levels of lidocaine, mepivacaine and bupivacaine, 3.1 micrograms/ml, 2.7 micrograms/ml and 1.5 micrograms/ml, respectively) and within a range normally achieved clinically. None of the drugs tested affected resting ventilation or ventilation stimulated by hypercarbia. The drugs tested exerted a slight stimulatory effect on ventilation during hypoxemia.

Adult↗
PubMed1999

Topical use of local anesthetics in neonates.

INTRODUCTION: Various local anesthetics as in lidocaine ointment, amethocaine cream and EMLA cream are used topically for minor invasive interventions, such as venipuncture, both in children and adults. Since neonates have a nervous system that, albeit immature, enables them to feel pain, analgesia for these procedures is also indicated. Several studies in neonates have been carried out to establish effectiveness and safety of topically applied local anesthetics. These studies are reviewed in order to assess effectiveness and safety. METHODS: A Medline search was made in order to review all studies on effectiveness and safety of topical use of local anesthetics in neonates. Effectivity or safety studies using local anesthetics for circumcision were rejected. RESULTS: Seven studies on effectiveness were found: Three studies examined lidocaine ointment and four examined EMLA cream. Effectiveness of lidocaine ointment was questionable in two studies and negative in one. Effectiveness of EMLA cream was positive in two studies and negative in the other two. Four studies were found on safety of EMLA cream. All studies indicated that use of EMLA cream was safe. DISCUSSION: The poor effectiveness found in the reviewed studies is possibly due to too long an application time, a lipophilic carrier used and difficulties in assessing pain. The time of application is often based upon studies in children. Since the skin of neonates acts more as a mucosa than as mature skin the local anesthetics are able to cross this barrier more rapidly. Also a high bloodflow in the heel enhances the uptake of the drug. The application time in neonates should therefore be reduced compared to children. The use of a lipophilic carrier should be avoided since a lipophilic carrier impedes the local anesthetic to be absorbed, leading to reduced effect. Various methods of pain assessment were being used. Since not all methods used are validated it is difficult to obtain an objective end point. CONCLUSION AND RECOMMENDATION: The articles reviewed are non conclusive in their results of effective analgesia. Due to a lipophilic base form and a hydrophilic matrix EMLA cream is most effective. An application time of 30 minutes is recommended. In spite of the present precautions due to fear of methemoglobinemia, use of EMLA cream proved to be safe when used once a day. Since the clinical situation often requires more than one application a day, more research is needed to establish a safe and effective local anesthetic which can be applied topically several times a day in the neonate.

Administration, Topical↗