lidocaine topical (Rx, OTC)

Frequency Not Defined

Cardiovascular (with excessive systemic absorption): CV depressant effect characterized by bradycardia, hypotension, and cardiovascular collapse, which may lead to cardiac arrest

Allergic: Cutaneous lesions, urticaria, edema, or anaphylactoid reactions

Central nervous system

• CNS manifestations are excitatory and/or depressant and may be characterized by lightheadedness, nervousness, apprehension, euphoria, confusion, dizziness, drowsiness, tinnitus, blurred or double vision, vomiting, sensations of heat, cold or numbness, twitching, tremors, convulsions, unconsciousness, respiratory depression, and arrest
• Excitatory manifestations may be very brief or may not occur at all, in which case the first manifestation of toxicity may be drowsiness merging into unconsciousness and respiratory arrest
• Drowsiness following the administration of lidocaine is usually an early sign of a high blood level of the drug and may occur as a consequence of rapid absorption

Contraindications

Hypersensitivity to drug or amide type anesthetic

Cautions

Some formulations may contain sulfites

Contact with eye may cause severe eye irritation; if eye contact occurs, immediately wash out the eye with water or saline and protect eye until sensation returns

Patients with severe hepatic disease are at greater risk of developing toxic blood concentrations of lidocaine due to inability to metabolize lidocaine normally

When used concomitantly with other products containing local anesthetic agents, the amount of lidocaine absorbed from all formulations must be considered

Application to broken or inflamed skin, although not tested, may result in higher blood concentrations of lidocaine from increased absorption; apply only to intact skin

Jelly for endotracheal use

• When used for endotracheal tube lubrication care should be taken to avoid introducing the jelly into the lumen of the tube
• Do not use the jelly to lubricate the endotracheal stylettes
• If allowed into the inner lumen, the jelly may dry on the inner surface leaving a residue which tends to clump with flexion, narrowing the lumen
• There have been rare reports in which this residue has caused the lumen to occlude

Excessive systemic absorption

• Sepsis, severely traumatized mucosa, or open wounds in the area of application (potential for rapid systemic absorption)
• Doses applied to large surface areas that remain on the skin for >2 hr
• Repeated doses with short dosing intervals

2% Viscous solution

• Parents and caregivers should be cautioned about the following:
• Use special care for patients <3 years of age to accurately measure prescribed dose and not to administer product more often than prescribed
• Use a measuring device to carefully measure correct volume
• Use product for prescribed indication only
• Keep product container should be tightly closed and product stored well out of reach of all children immediately after each use
• If patient shows signs of systemic toxicity (e.g., lethargy, shallow breathing, seizure activity) seek emergency medical attention immediately with no additional product administered
• Discard unused product in manner that prevents possible exposure to children and pets
• When topical anesthetics used in mouth or throat, production of topical anesthesia may impair swallowing and thus enhance danger of aspiration; food should not be ingested for 60 min following use of local anesthetic preparations in mouth or throat area especially in children because of their frequency of eating; numbness of tongue or buccal mucosa may increase danger of biting trauma (food and/or chewing gum should not be used while mouth or throat area is anesthetized)

Pregnancy

There are no available data regarding use in pregnant women

Reproduction studies with lidocaine have been performed in rats at doses up to 30 mg/kg SC and have revealed no evidence of harm to the fetus due to lidocaine

There are, however, no adequate and well-controlled studies in pregnant women

Because animal reproduction studies are not always predictive of human response, should be used during pregnancy only if clearly needed

Lactation

There are no available data regarding use in breastfeeding women; caution if administered

Lidocaine is excreted in human milk, and the milk: plasma ratio of lidocaine is 0.4

Pregnancy Categories

A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

NA: Information not available.

Mechanism of Action

Elicits local anesthesia; stabilizes the neuronal membrane by inhibiting the ionic fluxes required for the initiation and conduction of impulses, thereby effecting local anesthetic action

Absorption

Onset of action: 3-5 minutes (eg, gel, cream, ointment)

Metabolism

It is not known if lidocaine is metabolized in the skin

Lidocaine is metabolized rapidly by the liver to a number of metabolites, including monoethylglycinexylidide (MEGX) and glycinexylidide (GX), both of which have pharmacologic activity similar to, but less potent than that of lidocaine

Elimination

Half-life: 81-149 minutes (IV)

Total body clearance: 0.33-0.9 L/min

Excretion: Kidneys (<10% unchanged)