Lidocaine Chloroprocaine

The primary site of action of epidurally administered agents is on the spinal nerve roots. As with spinal anesthesia, the choice of drug to be used is determined primarily by the duration of anesthesia desired. However, when a catheter has been placed, short-acting drugs can be administered repeatedly. Bupivacaine is typically used when a long duration of surgical block is needed. Lidocaine is used most often for intermediate length procedures chloroprocaine is used when only a very short duration of anesthesia is required. 

Epidural anesthesia This term is understood to be an introduction of local anesthetic into the spinal cord membrane of the intervertebral space. It is used during obstetrical and gynecological interventions that do not require a fast development of anesthesia. Drugs such as lidocaine, mepivacaine, bupivacaine, ethidocaine, and chloroprocaine are used for this purpose. 

Local anaesthetics are rarely associated with localised nerve damage. There have been a number of reports of prolonged motor and sensory deficits after large doses of chloroprocaine. This is believed to be related to the antioxidant sodium bisulphite. Radiculopathy has been reported following the subarachnoid administration of lidocaine (lignocaine) 5%. 

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-... 

When applied at excessively high concentrations, all local anesthetics can be toxic to nerve tissue. Chloroprocaine and lidocaine appear to be more neurotoxic than other local anesthetics when used... 

Chloroprocaine may have a similar action. Lidocaine also interacts, although the mechanism is not clear unless very high doses are used (398). 

Procaine and cocaine are esters that are hydrolysed by plasma cholinesterase and may therefore competitively enhance the action of suxamethonium (succinylcholine) (279). Chloroprocaine may have a similar action. Lidocaine also interacts, although the mechanism is not clear unless very high doses are used (280). 

When 20 patients each received 40 ml of 0.5 % chloropro-caine or 0.5 % lidocaine for intravenous regional anesthesia, chloroprocaine caused a significantly higher incidence of a metallic taste (22 versus 0%) than hdocaine when the study was repeated using alkahnized instead of plain chloroprocaine, there was no significant difference between the groups (280). 

Skin infiltration with local anesthetics can cause pain. The pain experienced during skin infiltration of lidocaine, chloroprocaine, and buffered solutions of both has been studied in 22 volunteers in a double-blind, randomized study (361). The pH of the solutions was unrelated to the pain score, but both formulations of chloroprocaine were significantly less painful than lidocaine. 

Lavin PA, Henderson CL, Vaghadia H. Non-alkalinized and alkalinized 2-chloroprocaine vs lidocaine for intravenous regional anesthesia during outpatient hand surgery. Can J Anaesth 1999 46(10) 939-45. 

Marica LS, O Day T, Janosky JE, Nystrom EU. Chloroprocaine is less painful than lidocaine for skin infiltration anesthesia. Anesth Analg 2002 94(2) 351. ... 

A study on the use of chloroprocaine 3%, bupivacaine 0.5% or a mixture of chloroprocaine 1.5% with bupivacaine 0.375% in obstetric epidural anaesthesia found that time to onset of analgesia, time to maximum analgesia, and effectiveness of analgesia were similar irrespective of the treatment regimen. Bupivacaine 0.5% alone had a longer duration of action than chloroprocaine or the mixture of anaesthetics. Another study found that lidocaine did not affect the pharmacokinetics of bupivacaine. ... 

Two studies " have found that chloroprocaine decreases the duration of epidural morphine analgesia (16 hours for chloroprocaine compared with 24 hours for lidocaine ). Another study found that morphine requirements after caesarean section were much higher in women who had received chloroprocaine for epidural anaesthesia than in those receiving Udocaine. The authors of one of the studies suggest that chloroprocaine should be avoided if epidural morphine is used. Epidural fentanyl also appears to be antagonised by chloroprocaine. ... 

One of the first uses of local anesthetics (LA) for anesthesia was in the late nineteenth century with William Halsted reporting a mandibular block and brachial plexus block using cocaine [37,38]. The chemical structure of local anesthetics in clinical use consists of an aromatic (lipophilic) benzene ring linked to an amino group (hydrophflic) via either an ester or an amide intermediate chain. The intermediate link classifies the local anesthetic as either an ester (procaine, chloroprocaine, tetracaine, and cocaine) or an amide (lidocaine, prilocaine, mepivacaine, bupi-vacaine, etidocaine, and ropivacaine). 

Epidural chlorprocaine the efficacy and duration of epidural morphine analgesia is diminished when administered after 2-chloroprocaine compared with lidocaine. The mechanism of the interaction between 2-chloroprocaine and morphine is unknown. The observed interaction between epidural morphine and 2-chloroprocaine may be a result of differences in onset and duration of action of the two drugs. 

Clinical presentation of systemic toxicity is variable, depending on the specific agent. Several agents are so rapidly metabolized that toxicity symptoms are very rarely seen, as with procaine and chloroprocaine. Different drugs present toxic symptoms in different sequence. For example, lidocaine first presents with dizziness or a numb tongue whereas bupivicaine is generally associated with dose-dependent depression of myocardial contractility and conduction and may result in fatal ventricular dysrhythmias. 

Nervous System A recent review analysed the available data on chloroprocaine and its use in intrathecal anesthesia [35 ]. The authors conclude that preservative-free chloroprocaine is an effective alternative to lidocaine to provide spinal anesthesia for short cases with a much lower rate of transitory neurological symptoms (TNS). Its recent approval in Europe may herald increased utilisation and availability. 

A prospective randomised double-blind controlled trial comparing lidocaine and chloroprocaine for outpatient transurethral prostatectomy yielded similar clinical end points (primary end point duration of spinal block) [36 ]. Four patients in the lidocaine group developed TNS and one patient in the chloroprocaine group developed an acute cauda equina syndrome, which fully recovered after several weeks. Based on this, the authors conclude that they cannot recommend lidocaine in view of the high incidence of TNS and recommend close follow-up for chloroprocaine to ensure its safety profile. 

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