Lidocaine is a local anesthetic that is good for surface application and injection. When injected around a nerve, it blocks conduction within 3 minutes. Vasodilatation also occurs in the injected area.
Mechanism of action.
- It is a Class 1B antiarrhythmic;
- It combines with fast Na ion channels and thereby inhibits recovery after repolarization, leading to decreased myocardial excitability and conduction velocity.
Clinical uses.
- Acute management of ventricular arrhythmias.
- Hemodynamically Stable Monomorphic Ventricular Tachycardia.
As local anesthesia, it is administered during :
- Infiltration,
- Nerve block,
- Epidural,
- Spinal
- Intravenous regional block
- Surface application.
Adverse effects.
- CVS: Hypotension, cardiac arrest, cardiac arrhythmias.
- Skin: Edema, erythema at the injection site, petechiae, and skin irritation.
- GIT: Constipation, Nausea, and vomiting
- Hematologic: Methemoglobinemia.
- Anaphylactic reactions.
- CNS: Confusion, dizziness, headache, paresthesia, seizure, somnolence, tremor.
Drug interaction.
- Lidocaine increases the levels of lomitapide by affecting hepatic and intestinal enzyme CYP3A4 metabolism.
- The drug increases the effects of dofetilide by pharmacodynamic synergism.
Contraindication.
· Hypersensitivity to lidocaine or amide-type local anesthetic.
· Patients with SA/AV/intraventricular heart block without an artificial pacemaker.
· Congestive heart failure.
· Cardiogenic shock
· Wolff-Parkinson-White Syndrome.
Toxicity.
Overdose causes :
- Muscle twitching,
- Convulsions and cardiac arrhythmias,
- Decrease in BP,
- Coma and respiratory arrest.
Dosage.
- XYLOCAINE, GESICAIN 4% topical solution, 2% jelly, 2% viscous, 5% ointment, 1% and 2% injection (with or without adrenaline), 5% heavy (for spinal anaesthesia).
