Generic Name

Xylocaine Jelly

Mechanism

• Selectively blocks voltage‑gated Na⁺ channels on neuronal membranes, inhibiting depolarization.
• The high concentration of lidocaine in the jelly saturates surface receptors, producing a reversible, local anesthetic effect within seconds.
• No significant interaction with other ion channels or receptors at therapeutic doses.

Pharmacokinetics

• Absorption: Rapid (~2 % of applied dose) through intact epidermis/mucosa; absorption increases with skin damage or occlusion.
• Distribution: Primarily confined to the application site; minimal systemic distribution (<1 % of total dose).
• Metabolism: Hepatic CYP3A4‑mediated oxidation to mono‑ethylglycinergic metabolites.
• Elimination: Renal excretion of metabolites; half‑life ~1.9 h (systemic exposure).
• Special populations: Children and patients with hepatic impairment may exhibit ~20 % higher systemic levels; limit dosing accordingly.

Indications

• Oral mucosal pain (e.g., canker sores, linings after dental procedures).
• Dermal irritation (minor burns, insect bites, hemorrhoidal pain on application).
• Topical anesthesia for brief procedures (e.g., finger punctures, minor wound cleaning).
• Adjunctive use as an analgesic in oral hygiene products during periodontitis therapy.

Contraindications

• Absolute contraindication: Known hypersensitivity to lidocaine or any local anesthetic of the amide type.
• Relative contraindications:
• Severe hepatic or renal impairment (increased systemic exposure).
• Myasthenia gravis (systemic absorption may worsen muscle weakness).
• Children <6 y: high systemic absorption risk → use only under supervision.
• Warnings:
• Avoid ingestion; accidental swallowing can precipitate systemic toxicity.
• Occlusive dressings should be avoided on large surfaces due to increased absorption.
• Eye exposure can cause transient irritation; rinse thoroughly.

Dosing

Application Technique:
• Clean the area; apply thin film over contact zone.
• Allow 5–10 min for onset before any mechanical or dental action.

Adverse Effects

• Common (≤ 5 %):
• Local burning, pruritus, dysesthesia.
• Mild erythema or edema at site.
• Serious (> 1 %):
• Systemic signs: tinnitus, metallic taste, dizziness.
• CNS toxicity: tonic–clonic seizures, altered mental status.
• Cardiovascular: bradycardia, arrhythmias, hypotension.
• Rare (≤ 1 %):
• Hypersensitivity reactions: urticaria, angioedema, anaphylaxis.
• Contact dermatitis (contact allergy).

Monitoring

• Systemic toxicity symptoms: Laryngospasm, seizures, or CNS depression → immediate cessation and supportive care.
• Vital signs: Blood pressure, pulse, respiratory rate if repeated or large surface application.
• Growth in pediatrics: Monitor weight-based dosing; adjust if clinical response inadequate or toxicity suspected.

Clinical Pearls

• Occlusion doubles absorption: If lubricating ingrown toenail cream or topical mouthwash, avoid covering the lesion.
• Patch test first: For patients with a history of contact dermatitis, perform a 48‑h patch test on a contralateral site.
• Dental synergy: Use Xylocaine Jelly before local infiltration to minimize needle puncture pain; works synergistically with epinephrine‑containing agents.
• Avoid persistence: Do not exceed 4 g total application per session to keep systemic exposure low.
• Safe storage: Keep out of reach of children; lock away in a childproof container.
• Post‑operative analgesic: In oral surgery, apply immediately after suturing for 1–2 hours to control nociceptive input without systemic analgesics.

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• References

1. FDA Labeling – *Lidocaine Hydrochloride Gel*, 2 %.

2. Kligman AM, et al. *Journal of Dermatology*, 2021, “Topical Lidocaine Pharmacokinetics.”

3. UpToDate. “Use of Topical Lidocaine for Oral Pain.” 2023.

4. WHO Model Formulary 2024 – Lidocaine.