Lidocaine is an amide type local anaesth. It stabilises the neuronal membrane and inhibits Na ion movements, which are necessary for conduction of impulses. In the heart, lidocaine reduces depolarisation of the ventricles during diastole and automaticity in the His-Purkinje system. Duration of action potential and effective refractory period are also reduced.
Locaine Injection 2%
Intramuscular: Emergency treatment of ventricular arrhythmias: 300 mg injected into the deltoid muscle, repeat after 60-90 min if necessary.
Intraspinal: Spinal anaesthesia: As hyperbaric soln of 1.5% or 5% lidocaine in 7.5% glucose soln. Normal vaginal delivery: Up to 50 mg (as 5% soln) or 9-15 mg (as 1.5% soln). Caesarian operation: Up to 75 mg (as 5% soln). Other surgical procedures: 75-100 mg.
Intravenous: Pulseless ventricular fibrillation or ventricular tachycardia : 1-1.5 mg/kg repeated as necessary. Max: 3 mg/kg. For ventricular arrhythmias in more stable patients: Usual loading dose: 50-100 mg as an IV inj at 25-50 mg/min, may repeat once or twice up to a max of 200-300 mg in 1 hr, followed by 1-4 mg/min via continuous IV infusion. May need to reduce dose if the infusion is longer than 24 hr.
Intravenous: Intravenous regional anaesthesia: As 0.5% soln w/o epinephrine: 50-300 mg. Max: 4 mg/kg.
Percutaneous infiltration anaesthesia: As 0.5% or 1% soln: 5-300 mg.
Sympathetic nerve block: As 1% soln: 50 mg for cervical block or 50-100 mg for lumbar block.
Peripheral nerve block:
As 1.5% soln: For brachial plexus block: 225-300 mg.
As 2% soln: For dental nerve block: 20-100 mg.
As 1% soln: For intercostal nerve block: 30 mg;
For paracervical block: 100 mg on each side, repeated not more frequently than every 90 min;
For paravertebral block: 30-50 mg;
For pudendal block: 100 mg on each side.
As 4% soln: For retrobulbar block: 120-200 mg.
The maximum dose is 200 mg (Approximately 20 spray).
In dentistry, the normal dose is 1-5 sprays. Two sprays per quarter of the mouth is recommended, with a maximum of 3 sprays per quarter of the mouth over 30 minutes.
In sinus procedures 3 sprays are used.
In procedures of the throat and windpipe, up to 20 sprays may be necessary.
Up to 20 sprays may be necessary in childbirth (cesarian procedure).
Lower doses are used for children aged 3-12 years. Lidocaine 10% Spray is not recommended for children under 3 years.
Topical: Anaesthesia before e.g. venepuncture (not for infants), apply a thick layer under an occlusive dressing 1-5 hours before procedure; split skin grafting, apply a thick layer under an occlusive dressing 2-5 hours before procedure; genital warts (not for children), apply up to 10 gm 5-10 minutes before removal.