Procaine lidocaine

Local anesthetics interact with peripheral nerve cell membranes and exert a pharmacological effect [34]. Potential oscillation was measured in the presence of 20 mM hydrochlorides of procaine, lidocaine, tetracaine, and dibucaine (structures shown in Fig. 16) [19]. Amplitude and the oscillatory and induction periods changed, the extent depending on the... 

Vasoconstrictor substances such as epinephrine reduce systemic absorption of local anesthetics from the injection site by decreasing blood flow in these areas. This is important for drugs with intermediate or short durations of action such as procaine, lidocaine, and mepivacaine (but not prilocaine). 

This question of direct interaction with nerve proteins or indirect interaction via membrane perturbation has also been tackled by ESR spectroscopy. Two types of labeling have been used fatty acids for lipid labeling and maleimide for frog nerve proteins. The anesthetics used were halothane as an example of a general anesthetic and procaine, lidocaine, and tetracaine as examples of local anesthetics. The latter interact primarily with head groups but can also merge into the hydrophobic hydrocarbon... 

Two to three injection sites may be needed to provide adequate anesthesia. For minor surgical procedures of the eyelid, the volume of anesthetic required would be far less than the maximum dose of most local anesthetics (e.g., procaine, lidocaine, and mepivacaine)—approximately 500 mg as a 1% or 2% solution.A ring block or field block may be used to anesthetize around the area of the surgical site in a circumferential manner without injecting... 

Usubiaga JE, Wikinski JA, Morales RL, Usubiaga LE. Interaction of intravenously administered procaine, lidocaine and succinylchohne in anesthetized subjects. Anesth Analg 1967 46(I) 39-45. 

Lidocaine (Xylocaine, others), an aminoethylamide is the prototypical amide local anesthetic. Lidocaine produces faster, more intense longer lasting, and more extensive anesthesia than does an eqnal concentration of procaine. Lidocaine is an alternative choice for individuals sensitive to ester-type local anesthetics. 

Examples Possible resonance structures of procaine, lidocaine and tetracaine are as describe below ... 

Spinal anaesthesia (spinal block or sub-arachnoid block) is used to administer the injection into the subarachnoid space. Several local anaesthetics are used for spinal anaesthesia such as procaine, lidocaine, tetracaine, and bupivacaine. Vasoconstrictors such as adrenaline (0.1-0.2 mg) and phenylephrine (0.5-2 mg) can be added to subarachnoid blocks to decrease vascular uptake and prolong diuation of action. 

FIG. 16 Chemical structures of (a) procaine hydrochloride, (b) lidocaine hydrochloride, (c) tetracaine hydrochloride, and (d) dibucaine hydrochloride. 

Local anesthetics Dibucaine Procaine Tetracaine Lidocaine Benzyl alcohol... 

FIG. 1 Molecular structures of the drugs examined in the delivery study the general anesthetics, alkanols (I), halothane (II), enflurane (III), isoflurane (IV), halogenated cyclobutane (V) the local anesthetics, dibucaine hydrochloride (VI), procaine hydrochloride (VII), tetracaine hydrochloride (VIII), lidocaine hydrochloride (IX), benzyl alcohol (X) the endocrine disruptor, bisphenol A (XI), and alkylbenzenes, benzene (XII), toluene (XIII), ethylbenzene (XIV), and propylbenzene (XV). 

Procaine Amethocaine Lidocaine Prilocaine Bupivicaine Ropivicaine Mepivicaine... 

Drugs such as lidocaine, mepivacaine, bupivacaine, ethidocaine, and procaine are primarily used for this purpose. 

Procainamide and lidocaine are two of the primary drugs for treating cardiac arrhythmias. Since lidocaine has a short duration of action, it is common to administer it by continuous infusion. Procainamide, because of its amide linkage, has longer action than does its precursor, procaine. Orally active analogues of local anesthetics (e.g., mexiletine) also are used as antiarrhyth-mics (see Chapter 16). 

Lidocaine hydrochloride Xylocaine) is the most commonly used local anesthetic. It is well tolerated, and in addition to its use in infiltration and regional nerve blocks, it is commonly used for spinal and topical anesthesia and as an antiarrhythmic agent (see Chapter 16). Lidocaine has a more rapidly occurring, more intense, and more prolonged duration of action than does procaine. 

C. Lidocaine is well tolerated and has a rapid onset and an adequate duration of action for most procedures. Bupivacaine has a particularly long duration of action. This may be advantageous in certain procedures, but not in most. Procaine has a relatively slow onset of action as well as a short duration of action. Etidocaine shows a preference for motor rather than sensory block this limits its effectiveness in obstetrics. 

Historically, local anesthetics have been known for many years. Cocaine, the first such agent, was isolated in 1860 and introduced for clinical application in 1884. Procaine was developed as a synthetic analog of cocaine in 1905 and lidocaine was synthesized in 1943. The development of new chemical entities as putative local anesthetics remains an ongoing activity in medicinal chemistry. 

The local anesthetics can be broadly categorized on the basis of the chemical nature of the linkage contained within the intermediate alkyl chain group. The amide local anesthetics include lidocaine (7.5), mepivacaine (7.6), bupivacaine (7.7), etidocaine (7.8), prilocaine (7.9), and ropivacaine (7.10) the ester local anesthetics include cocaine (7.11), procaine (7.12), benzocaine (7.13), and tetracaine (7.14). Since the pharmacodynamic interaction of both amide and ester local anesthetics with the same Na" channel receptor is essentially idenhcal, the amide and ester functional groups are bioisosterically equivalent. However, amide and ester local anesthetics are not equal from a pharmacokinetic perspective. Since ester links are more susceptible to hydrolysis than amide links. 

Several first-generation Hi antagonists are potent local anesthetics. They block sodium channels in excitable membranes in the same fashion as procaine and lidocaine. Diphenhydramine and promethazine are actually more potent than procaine as local anesthetics. They are occasionally used to produce local anesthesia in patients allergic to conventional local anesthetic drugs. A small number of these agents also block potassium channels this action is discussed below (see Toxicity). 

The choice of local anesthetic for infiltration, peripheral nerve blocks, and central neuraxis (spinal/epidural) blockade is usually based on the duration of action required. Procaine and chloroprocaine are short-acting lidocaine, mepivacaine, and prilocaine have an intermediate duration of action and tetracaine, bupivacaine, levobupivacaine, and ropivacaine are long-... 

Procaine Like lidocaine Like lidocaine Very short procedures Parenteral duration 15-30 min 30-90 min with epinephrine Toxicity Like lidocaine... 

Clinical use Because of its poor penetration of intact mucous membranes, procaine is largely ineffective for topical applications and has been mainly used in injection in combination with adrenaline, although in general it has been replaced by other LAs such as lidocaine. For infiltration anesthesia, 0.25 to 0.5 % solutions of procaine have been used in doses up to 600 mg. For peripheral nerve block, a common dose of 500 mg of procaine has been given as a 0.5 to 2.0 % solution. 

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