Details About Overdose or Poisoning Generic Salt :: Lidocaine
Lidocaine
Drug Pharmacology ::
I. Pharmacology./b>
Lidocaineis a local anesthetic and a type Ib antiarrhythmic agent. It inhibitsfast sodium channels and depresses automaticity within the His-Purkinjesystem and the ventricles but has a variable effect and may shorten theeffective refractory period and action potential duration. Conductionwithin ischemic myocardial areas is depressed, abolishing reentrantcircuits. Unlike quinidine and related drugs, lidocaine exerts aminimal effect on the automaticity of the sinoatrial node and onconduction through the AV node and does not decrease myocardialcontractility or blood pressure in usual doses. It also has rapid”on-off” binding to sodium channels (to allow reactivation of thechannel) and competes with other sodium channel blockers (that are slowto release and block the channel throughout the cardiac cycle). Thismay account for its antiarrhythmic effect with poisonings from othersodium channel blockers (type 1a antiarrhythmics, tricyclicantidepressants).
Theoral bioavailability of lidocaine is poor owing to extensive first-passhepatic metabolism (although systemic poisoning is possible fromingestion). After intravenous administration of a single dose, theonset of action is within 60–90 seconds and the duration of effect is10–20 minutes. The elimination half-life of lidocaine is approximately1.5–2 hours; active metabolites have elimination half-lives of 2–10hours. Lidocaine clearance declines with continuous infusions and maybe attributable to its metabolite monoethylglycinexylidide (MEGX). Drugaccumulation may occur in patients with congestive heart failure orliver or renal disease.
Drug Indications ::
Indications. Lidocaineis used for the control of ventricular arrhythmias arising frompoisoning by a variety of cardioactive drugs and toxins (eg, digoxin,cyclic antidepressants, stimulants, and theophylline). Patients withatrial arrhythmias usually do not respond to this drug.
Drug Contra-Indications ::
III. Contraindications./b>
Thepresence of nodal or ventricular rhythms in the setting of third-degreeAV or intraventricular block. These are usually reflex escape rhythmsthat may provide lifesaving cardiac output, and abolishing them mayresult in asystole.
Hypersensitivity to lidocaine or other amide-type local anesthetics (rare).
Drug Adverse Effects ::
IV. Adverse effects
Excessive doses produce dizziness, confusion, agitation, and seizures.
Conductiondefects, bradycardia, and hypotension may occur with extremely highserum concentrations or in patients with underlying conduction disease.
Use in pregnancy. FDA category B. Fetal harm is extremely unlikely (see Table III–1).
Drug Lab Interactions ::
Drug or laboratory interactions
Cimetidine and propranolol may decrease the hepatic clearance of lidocaine.
Lidocainemay produce additive effects with other local anesthetics. In severecocaine intoxication, lidocaine theoretically may cause additiveneuronal depression.
Drug Dose Management ::
Dosage and method of administration (adults and children)
Administer 1–1.5 mg/kg (usual adult dose 50–100 mg; children, 1 mg/kg)IV bolus at a rate of 25–50 mg/min, followed by infusion of 1–4 mg/min(20–50 mcg/kg/min) to maintain serum concentrations of 1.5–5 mg/L.
Ifsignificant ectopy persists after the initial bolus, repeat doses of0.5 mg/kg IV can be given if needed at 10-minute intervals (to amaximum 300 mg or 3 mg/kg total dose; children may be given repeat 1mg/kg doses every 5–10 minutes to a maximum of 5 mg/kg).
In patients with congestive heart failure or liver disease, use half the recommended maintenance infusion dose.
Drug Chemical Formulations ::
Formulations
Parenteral. Lidocainehydrochloride for cardiac arrhythmias (Xylocaine, others). Direct IV:1% (10 mg/mL), 2% (20 mg/mL) in 5-mL ampules and prefilled syringes,and 5- to 50-mL vials; 4%, 10%, and 20% in 1- and 2-g single-dose vialsor additive syringes for preparing intravenous infusions; 0.2% (in 500and 1000 mL), 0.4% (in 250 and 500 mL), and 0.8% (in 250 and 500 mL) inD5W solutions prepared for infusions.
The suggested minimum stocking level to treat a 70-kg adult for the first 24 hours is 10 prefilled 100-mg syringes and six 1-g vials for infusions.
