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PubMed1979

Etidocaine, a new local anesthetic.

Different local anesthetics have different physicochemical properties that result in different biological effects. Etidocaine (Duranest) is said to be a long-acting anesthetic with a rapid onset of action, properties that are particularly useful in busy office practices in which lengthy operative procedures are performed. Clinical testing confirmed that this anesthetic does, indeed, work in this manner, which makes it a good addition to the varieties of local anesthetics available.

Acetanilides↗
PubMed2000

Selective inhibition of monoamine neurotransmitter transporters by synthetic local anesthetics.

Synthetic local anesthetics (LAs) have been found to have cocaine-like characteristics with some psychotomimetic action, possibly through monoaminergic neurotransmission. To gain insight into the relation between LA action and monoamine transporters, we investigated the effect of synthetic LAs on neurotransmitter transporters, including monoamine transporters. We used cloned transporter cDNAs and examined transient functional expression in COS cells and stable expression in HeLa cells. Among the LAs tested, procaine and other ester-type LAs inhibited [3H]DA uptake and binding of [3H]2-beta-carbomethoxy-3-beta-(4-fluorophenyl)tropane (CFT), a cocaine analogue, in COS cells expressing rat dopamine transporter (DAT). The inhibition was concentration-dependent. The inhibitory effect on [3H]DA uptake was reversible and not dependent on pH, as observed in HeLa cells stably expressing DAT. Procaine also inhibited uptake of norepinephrine (NE) and serotonin (5-HT) by the norepinephrine transporter (NET) or serotonin transporter (SERT) expressed in COS cells. On the other hand, procaine and other LAs had little or no effect on [3H]GABA and [3H]glutamate uptake in COS cells expressing mouse GABA or rat glutamate/aspartate transporter. IC50 values for [3H]DA uptake inhibition correlated well with those for [3H]CFT binding inhibition, but not with intrinsic anesthetic potency. Kinetic analysis of monoamine uptake inhibition by procaine in COS cells expressing rat DAT, NET or SERT revealed a competitive action similar to that of cocaine. These results demonstrate that certain LAs selectively inhibit monoamine transporters. This might contribute to the cocaine-like psychotomimetic action of certain LAs.

Anesthetics, Local↗
PubMed1984

Mechanisms of use-dependent block of sodium channels in excitable membranes by local anesthetics.

Many local anesthetics promote reduction in sodium current during repetitive stimulation of excitable membranes. Use-, frequency-, and voltage-dependent responses describe patterns of peak INa when pulse width, pulse frequency, and pulse amplitude are varied. Such responses can be viewed as reflecting voltage-sensitive shifts in equilibrium between conducting, unblocked channels and nonconducting, blocked channels. The modulated-receptor hypothesis postulates shifts in equilibrium as the result of a variable-affinity receptor and modified inactivation gate kinetics in drug-complexed channels. An alternative view considers drug blocking in the absence of these two features. We propose that drug binds to a constant-affinity channel receptor where receptor access is regulated by the channel gates. Specifically, we view channel binding sites as guarded by the channel gate conformation, so that unlike receptors where ligands have continuous access, blocking agent access is variable during the course of an action potential. During the course of an action potential, the m and h gates change conformation in response to transmembrane potential. Conducting channels with both gates open leave the binding site unguarded and thus accessible to drug, whereas nonconducting channels, with gates in the closed conformation, act to restrict drug access to unbound receptors and possibly to trap drug in drug-complexed channels. We develop analytical expressions characterizing guarded receptors as "apparently" variable-affinity binding sites and predicting shifts in "apparent" channel inactivation in the hyperpolarizing direction. These results were confirmed with computer simulations. Furthermore, these results are in quantitative agreement with recent investigations of lidocaine binding in cardiac sodium channels.

Action Potentials↗
PubMed1975

[Relations between the physico-chemical properties, the chemical reactivity and the local anesthetic activity. 32. (Part 1): Binding capacity of a structural protein (wool) to local anesthetics].

1. The general part deals with the molecular structure of nerve membranes and different local-anesthetic substances as well as the various possibilities of local-anesthetic binding to the nerve membrane. Albumin is usually chosen as a model protein in such investigations, a short extract of which is given. 2. The special part includes the chemical composition and properties of wool macroprotein, the model system used in the present paper. We determined its protein-binding values with cinchocain and tetracain homologues and various known commercial products of local anesthetics (oxybuprocain, parethoxyprocain and tetracain). The binding constants of these substances on wool protein are shown. 3. A statistically confirmed relationship between the alkyl chain length and the strength of protein binding is given. The free energy per CH2-group ranges between 400 and 500 cal/mol and its larger in cases of low pH values. 4. From the present data, a relationship between the binding constant and the partition constant of each substance of the homologous series studied could easily be observed, which further makes it possible to estimate the characteristic protein-binding constant Kp and also the change in pi-values with the change in free reaction energy of the substances. 5. The large differences in the binding values of the different binding mechanisms, which most probably are dependent on the variable binding affinities of the functional groups as well as on steric factors. But as in the homologous series, only substituents like alkyl amino and alkoxy could be changed, the possibility of some other binding process depending on the alkyl chain length of these groups could not be ruled out. Since the alky groups are non-polar, hydrophobic binding plays a role.

Albumins↗
PubMed2006

Down-regulation of norepinephrine transporter function induced by chronic administration of desipramine linking to the alteration of sensitivity of local-anesthetics-induced convulsions and the counteraction by co-administration with local anesthetics.

Alterations of norepinephrine transporter (NET) function by chronic inhibition of NET in relation to sensitization to seizures induce by cocaine and local anesthetics were studied in mice. Daily administration of desipramine, an inhibitor of the NET, for 5 days decreased [(3)H]norepinephrine uptake in the P2 fractions of hippocampus but not cortex, striatum or amygdalae. Co-administration of lidocaine, bupivacaine or tricaine with desipramine reversed this effect. Daily treatment of cocaine increased [(3)H]norepinephrine uptake into the hippocampus. Daily administration of desipramine increased the incidence of appearance of lidocaine-induced convulsions and decreased that of cocaine-induced convulsions. Co-administration of lidocaine with desipramine reversed the changes of convulsive activity of lidocaine and cocaine induced by repeated administration of desipramine. These results suggest that down-regulation of hippocampal NET induced by chronic administration of desipramine may be relevant to desipramine-induced sensitization of lidocaine convulsions. Inhibition of Na(+) channels by local anesthetics may regulate desipramine-induced down-regulation of NET function. Repeated administration of cocaine induces up-regulation of hippocampal NET function. Desipramine-induced sensitization of lidocaine seizures may have a mechanism distinct from kindling resulting from repeated administration of cocaine.

Adrenergic Uptake Inhibitors↗
PubMed1991

[Can choice of medications and adjuvants reduce risks of local anesthetic complications?].

Local anesthetic agents in high concentrations may cause local irritation by ischemia especially after the use of adrenaline whereas felypressin has no tissue-irritating properties. Adrenaline but not felypressin increases the intravenous systemic toxicity. Noradrenaline has to be avoided as a vasoconstrictor. An aspiration test before injection will decrease the risk of inadvertent intravenous injection.

Adjuvants, Anesthesia↗
PubMed1999

[Studies of local anesthetics. CL. Models of the dependence of local anesthetic effectiveness of basic esters of alkoxy-substituted phenylcarbamic acids on capacity factor k'].

On the basis of proposed six models of the dependence of local anaesthetic effectiveness of series of alkoxysubstituted derivatives of phenylcarbamic acid, this activity was studies in dependence on the capacity factor k' as the parameter of lipophilicity. The most suitable models proved to be y = (Cx + Ci).k' for surface anaesthesia, and y = Cx + Ci log k' for infiltration anaesthesia, y being the value of the decadic logarithm of surface or infiltration local anaesthetic activity, Cx the coefficient characterizing the nitrogenous base, Ci the coefficient characterizing the individual alkoxygroups, and k' the capacity factor from HPLC.

Anesthetics, Local↗
PubMed2000

Comparative study on anesthetic potency of dental local anesthetics assessed by the jaw-opening reflex in rabbits.

The potency of 4 local anesthetics to dental pulp was compared. Drugs were 4% articaine with 12 microgram/mL epinephrine (A12), 4% articaine with 6 microgram/mL epinephrine (A6), 2% lidocaine with 12.5 microgram/mL epinephrine (L), and 3% propitocaine with 0.03 IU/mL felypressin (P). Local anesthetics were injected into the dental root of the mandibular incisor. Electromyogram (EMG) of the digastric muscle was measured during the jaw-opening reflex induced by electrical stimulation. The disappearance of the EMG wave was judged as positive evidence of anesthesia. The determination of ED50 of the anesthetic was made by probit analysis. The ED50 of the A12 was minimal in all the tested anesthetics throughout the entire course. The potency in the A6 was 2.8 times that of the L. The potency of the A12 at the 15-minute measurement was 3.8 times that of the A6. The ED50 of the P was higher compared with those of the other 3 groups. It was concluded that articaine showed quicker onset than lidocaine and propitocaine and that there was a need to increase the dosage to attain a quick onset or to extend the duration.

Anesthetics, Local↗
PubMedDate not supplied

Water-diluted local anesthetic for trigger-point injection in chronic myofascial pain syndrome: evaluation of types of local anesthetic and concentrations in water.

BACKGROUND AND OBJECTIVES: We have recently demonstrated that a mixture of 1% lidocaine with water in a 1:3 ratio has less injection pain and is more effective than unaltered 1% lidocaine in treating chronic myofascial pain syndromes. Yet, the most suitable local anesthetic and the most effective dilution in water have not been evaluated. METHODS: Various mixtures of local anesthetics and water or saline were injected intramuscularly into the shoulder of 40 female volunteers, and pain scores on injection were evaluated in a randomized and double-blinded manner. In another portion of the study, 0.25% or 0.2% lidocaine in water were injected randomly into 1 side of 21 outpatients with chronic neck, shoulder, or lumbar myofascial pain to the same degree in both sides. The other solution was injected into the other side of the same patients. RESULTS: Less injection pain was experienced with the water-diluted 0.25% lidocaine and water-diluted 0.25% mepivacaine than the saline-diluted 0.25% lidocaine and water-diluted 0.0625% bupivacaine. Also, less injection pain was experienced with the water-diluted 0.25% and 0.2% lidocaine than the water-diluted 0.3% and 0.15% lidocaine. In the other study, there were no differences in either the effectiveness or duration of analgesia between the 0.25% and 0.2% water-diluted lidocaine. CONCLUSIONS: The suitable type of local anesthetic may be lidocaine or mepivacaine, and the most effective water-diluted concentration is considered to be 0.2% to 0.25%.

Adult↗
PubMed2005

Marked hypotension induced by adrenaline contained in local anesthetic.

OBJECTIVES: Local anesthetics containing adrenaline, which often cause cardiovascular side effects, are routinely used in functional endoscopic sinus surgery (FESS) for the main purpose of hemostasis. The controversies concerning hemodynamic effects of adrenaline in local infiltration are widely discussed, but there is no definite conclusion. A prospective, randomized, double-blinded study was carried out to discover the hemodynamic effects after local infiltration of 1:200,000 adrenaline contained in 2% lidocaine under general anesthesia. STUDY DESIGN: Seventy-six adult patients undergoing FESS during general anesthesia were allocated randomly into three groups. Group I patients (n = 26) received 2% lidocaine 2 mL with adrenaline (1:200,000), group II patients (n = 25) received saline 2 mL with adrenaline (1:200,000), and group III patients (control group, n = 25) received saline 2 mL without adrenaline for local infiltration. Electrocardiogram (ECG) and heart rate (HR) were monitored simultaneously; systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial blood pressure (MAP) were directly measured in radial artery continuously after local infiltration. METHODS: SBP, DBP, MAP, and HR were recorded at 10 time points: before infiltration (baseline), 0.5 minutes, 1 minute, 1.5 minutes, 2 minutes, 2.5 minutes, 3 minutes, 3.5 minutes, 4 minute, and 5 minutes after infiltration. RESULTS: Significant hemodynamic changes, particularly hypotension (P < .01), after local infiltration were observed in group I and group II compared with the baseline, but not in group III. However, there were no significant hemodynamic changes between group I and group II at the same time points (P > .05). The significant hemodynamic changes lasted no longer than 4 minutes. CONCLUSIONS: Lidocaine (2%) or saline with adrenaline (1:200,000) does cause temporary hypotension and other hemodynamic changes during general anesthesia, which last no longer than 4 minutes. The causative mechanism is caused by the effect of adrenaline. This is a preliminary study.

Anesthesia, General↗