| Lidocaine |
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Information AboutLidocaine |
| CATEGORIES ABOUT LIDOCAINE | |
| antiarrhythmic agents | |
| local anesthetics | |
Lidocaine ( and Antiarrhythmic drug. Lidocaine is used topically to relieve itching, burning and pain from skin inflammations, injected as a dental anesthetic, and in minor surgery. The most commonly encountered lidocaine preparations are marketed by Abraxis Pharmaceutical Products under the brand names '''Xylocaine''' and '''Xylocard''', and as 'Lanacane' topical ointment in the UK, though lidocaine is also found in many other proprietary preparations. HISTORY Lidocaine, the first Amino Amide -type local anesthetic, was developed first by Nils Löfgren and Bengt Lundqvist in 1943 and first marketed in 1948 . PHARMACOKINETICS Lidocaine has a more rapid onset of action and longer duration of action than Amino Ester -type local anesthetics such as Procaine . It is approximately 90% metabolized in the Liver by CYP1A2 (and to a minor extent CYP3A4 ) to the pharmacologically-active Metabolites Monoethylglycinexylidide and Glycinexylidide . The elimination Half-life of lidocaine is approximately 1.5–2 hours in most patients. This may be prolonged in patients with Hepatic Impairment (average 343 minutes) or Congestive Heart Failure (average 136 minutes). (Thomson ''et al.'', 1973) PHARMACOLOGY Anesthesia Lidocaine alters depolarization in Neuron s, by blocking the fast Voltage Gated Sodium (Na+) Channels in the cell membrane. With sufficient blockade, the membrane of the presynaptic neuron will not depolarize and so fail to transmit an Action Potential , leading to its anesthetic effects. Careful titration allows for a high degree of selectivity in the blockage of sensory neurons, whereas higher concentrations will also affect other modalities of neuron signalling. CLINICAL USE Indications Indications for the use of lidocaine include:
Topical lidocaine has been shown to relieve Postherpetic Neuralgia in some patients, although there is not enough study evidence to recommend it as a First-line Treatment . (Khaliq ''et al.'', 2007) Contraindications Contraindications for the use of lidocaine include:
Adverse drug reactions Adverse Drug Reaction s (ADRs) are rare when lidocaine is used as a local anesthetic and is administered correctly. Most ADRs associated with lidocaine for anesthesia relate to administration technique (resulting in systemic exposure) or pharmacological effects of anesthesia, however Allergic reactions can rarely occur. Systemic exposure to excessive quantities of lidocaine mainly result in Central Nervous System (CNS) and Cardiovascular effects – CNS effects usually occur at lower Blood Plasma concentrations and additional cardiovascular effects present at higher concentrations, though cardiovascular collapse may also occur with low concentrations. CNS effects may include CNS excitation (nervousness, tingling around the mouth, Tinnitus , tremor, dizziness, blurred vision, Seizure s) followed by depression (drowsiness, loss of consciousness, Respiratory Depression and Apnea ). Cardiovascular effects include Hypotension , Bradycardia , Arrhythmia s, and/or Cardiac Arrest – some of which may be due to Hypoxemia secondary to respiratory depression. (Rossi, 2006) ADRs associated with the use of intravenous lidocaine are similar to toxic effects from systemic exposure above. These are dose-related and more frequent at high infusion rates (≥3 mg/minute). Common ADRs include: headache, dizziness, drowsiness, confusion, visual disturbances, , Bradycardia , Arrhythmia s, Cardiac Arrest , muscle twitching, Seizure s, Coma , and/or respiratory depression. (Rossi, 2006) Dosage forms Lidocaine, usually in the form of lidocaine hydrochloride, is available in various forms including:
ADDITIVE IN COCAINE Lidocaine is often added to Cocaine as a Diluent . Cocaine numbs the Gums when applied, and since lidocaine causes stronger gingival numbness, customers get the impression of high-quality cocaine when checking the purity this way even if the substance is of poor quality. Usage of lidocaine-diluted cocaine is dangerous due to the potential side effects of lidocaine including causing Cardiac Arrhythmia s. REFERENCES
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