Nerve block

Lidocaine hydrochloride [73-78-9] (Xylocaine), is the most versatile local anesthetic agent because of its moderate potency and duration of action, rapid onset, topical activity, and low toxicity. Its main indications are for infiltration, peripheral nerve blocks, extradural anesthesia, and in spinal anesthesia where a duration of 30 to 60 min is desirable. Because of its vasodilator activity, addition of the vasoconstrictor, epinephrine, increases the duration of action of Hdocaine markedly. It is also available in ointment or aerosol preparations for a variety of topical appHcations. 

Mepivacaine hydrochloride [1722-62-9] similar in profile to Hdocaine, is used for infiltration, peripheral nerve blocks, and extradural anesthesia. It appears to be less toxic than Hdocaine in adults but more toxic in newborns. The duration of action is longer than that of Hdocaine because of its lower vasodilator activity. Mepivacaine has Htde topical activity. 

Besides sodium channels, other ion channels such calcium- and potassium channels as well as certain ligand-gated channels are affected by local anaesthetics. However, this plays only a minor role for nerve block but may have more impact on adverse effects induced by systemical concentrations of these drags. 

After local anaesthetic injection, onset of nerve block and duration depends mainly on lipid solubility and on the region in where the diug is injected. In some formulations adrenaline is added to prolong the blocking action by inducing regional vasoconstriction and hereby reduce absorption and metabolisation. 

Other options for labor analgesia include spinal analgesia and nerve blocks. 

Nonpharmacologic therapies include reassurance and counseling, stress management, relaxation training, and biofeedback. Physical therapeutic options (e.g., heat or cold packs, ultrasound, electrical nerve stimulation, massage, acupuncture, trigger point injections, occipital nerve blocks) have performed inconsistently. 

S. B. A. Akerman, S. B. Ross, A. Tele, The Enzymatic Hydroysis of a Series of Ami-noacylanibdes in Relation to Their Nerve Blocking Effect and Toxicity , Acta Pharmacol. Toxicol. 1973, 32, 88-96. 

Q48 was synthesised to mimic the nerve-blocking activity of cocaine Q49 is indicated for dementia in Alzheimer s disease Q50 was originally derived from the bark of the yew tree... 

Benzocaine is an anaesthetic drug that was originally synthesised to mimic the nerve blocking activity of cocaine. 

Nerve axons, 7 Nerve blocks, 16 Nervous conduction, 7 Neuralgia, 85 Neuritis, 85... 

Local anesthetics are used for topical anesthesia, local infiltration, peripheral nerve block, paravertebral anesthesia, intravenous block also known as regional anesthesia, epidural block, and spinal i.e. subarachnoid blockade. The local anesthetics may be divided into two main groups, the esters and the amide-type agents. 

Amide-type agents include articaine, lidocaine, bupivacaine, prilocaine, mepivacain and ropiva-caine. These are metabolized in the liver by microsomal enzymes with amidase activity. The amide group is preferred for parenteral and local use. If by accident rapidly administered intravascularly these agents, especially bupivacaine but also lidocaine, can produce serious and potentially lethal adverse effects including convulsions and cardiac arrest. They can more easily accumulate after multiple administrations. Intravenous lidocaine is sometimes used for regional anesthesia, for infiltration procedures, for the induction of nerve blockade and for epidural anesthesia. However, it is also used as an antiarrhythmic. Bupivacaine is a long-acting local anesthetic used for peripheral nerve blocks and epidural anesthesia. 

The use of local anaesthetics outside specialized surgical or anaesthetical practice is usually limited to infiltration anaesthesia, different surface anaesthetic methods, and (nerve) block of fingers and toes. Lo-... 

Nerve block anaesthesia in general practice mostly concerns finger or toe blocks. Lidocaine or prilocaine, 10 mg/ml without adrenaline (norepinephrine), is used and is injected on each side of the finger or toe, in two portions by the four nerve branches. Injection of larger volumes than 1-2 ml/side carries a risk of ischaemia because of the firm tissue. The transport through the nerve sheath takes a few minutes, and for a satisfactory result one should wait 5-10 minutes before the planned intervention starts. 

The first clinical uses of a local anesthetic agent occurred in 1884, when cocaine was employed as a topical agent for eye surgery and to produce a nerve block. These events inaugurated a new era, that of regional anesthesia. New applications were developed, including spinal, epidural, and caudal anesthesia. The search for a better local anesthetic led to chemical synthesis of a number of other compounds that have more selective local anesthetic properties and few systemic side effects. 

Procaine hydrochloride Novocain) is readily hydrolyzed by plasma cholinesterase, although hepatic metabolism also occurs. It is not effective topically but is employed for infiltration, nerve block, and spinal anesthesia. It has a relatively slow onset and short (1 hour) duration of action. All concentrations can be combined with epinephrine. It is available in dental cartridges with phenylephrine as the vasoconstrictor. 

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. 

Procaine is ineffective when administered through surface application, and is used only by injection. The onset of action for the drug is 2 to 5 minutes, and its duration of action is short. Vasoconstrictors are usually co-administered with this vasodilator drug to delay its absorption and to increase the duration of action. The drug is used for infiltration anesthesia, peripheral nerve block, and spinal anesthesia. 

Dental or surgical procedures, childhirth Infiltration or Nerve Block Local anesthetic dosage varies with procedure, degree of anesthesia, vascularity, duration. Maximum dose 4.5 mg/kg. Do not repeat within 2 hr. 

Peripheral or sympathetic nerve block (regional anesthesia) Topical Up to 200 ml of a... 

Regional nerve block anesthesia— injection of a small amount of local anesthetic into the tissue immediately surrounding a nerve supplying the region to be anesthetized... 

Local anaesthetics are employed routinely in dentistry by nerve block or by infiltration and/or regional block techniques to cary out varous operative procedures. 

Lignocaine injections are indicated for production of local or regional anaesthesia by infiltration techniques such as percutaneous injection, peripheral nerve block, spinal or subarachnoid block. 

It is a potent and long acting local anaesthetic used for spinal, infiltration, epidural anaesthesia and nerve block. 

Newer compound, long acting local anaesthetic which produces less cardiotoxicity. It is used mainly for nerve block and in postoperative pain. It is occasionally used in dentistry. 

Adrenaline along with local anaesthetics may be used for infiltration, nerve block and spinal anaesthesia for prolonging the action and to reduce the systemic toxicity of local anaesthetics. 

Bupivacaine is an amide compound with a duration of nerve blocking effect of around 3 hours. It is about four times more potent than lidocaine (lignocaine) and has an intermediate-to-slow onset of action. Bupivacaine is prepared as the hydrochloride salt in aqueous solutions in concentrations of 0.25%, 0.50%, and 0.75%. The incidence of motor block increases with increasing concentration. High doses of bupivacaine are associated with cardiac toxicity. Particular care must be exercised to avoid inadvertent overdosage or when the drug is administered to patients taking concurrent cardioactive medication. 

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