Usage
This drug combination is primarily used for local anesthesia. It belongs to the pharmacological class of local anesthetics, combined with a vasoconstrictor and preservatives. The mechanism of action involves blocking nerve conduction by inhibiting sodium channels, thus preventing the transmission of pain signals. Adrenaline acts as a vasoconstrictor, prolonging the anesthetic effect of lidocaine and reducing bleeding at the injection site. Methylparaben and sodium metabisulphite are preservatives. Sodium chloride adjusts the tonicity of the solution.
Alternate Names
No standard international non-proprietary name (INN) exists for this specific combination. It is commonly referred to as “Lidocaine with Adrenaline” or “Lignocaine with Epinephrine.” Brand names vary depending on the manufacturer and region, including Xylocaine with Adrenaline and Lox 2-Adr.
How It Works
Pharmacodynamics: Lidocaine blocks voltage-gated sodium channels in nerve fibers, inhibiting depolarization and blocking nerve impulse propagation. Adrenaline activates alpha-adrenergic receptors, causing vasoconstriction, reducing local blood flow, and extending lidocaine’s duration of action. Methylparaben and sodium metabisulphite act as antimicrobial preservatives. Sodium chloride maintains isotonicity of the solution.
Pharmacokinetics: Lidocaine is rapidly absorbed following injection, especially with adrenaline. It is metabolized primarily in the liver and excreted by the kidneys. Adrenaline is rapidly inactivated in the body by enzymes catechol-O-methyltransferase (COMT) and monoamine oxidase (MAO).
Dosage
Standard Dosage
Adults: The maximum single dose of lidocaine with adrenaline should not exceed 7 mg/kg (up to 500 mg total) in a 70 kg adult. Dosage is adjusted based on the patient’s response and the site of administration.
Children: Dosing in children over 3 years of age should be calculated based on age and weight, not exceeding 4.5 mg/kg (without epinephrine) or 7 mg/kg (with epinephrine). For example, a 5-year-old child weighing 50 lbs (22.7 kg) should receive no more than 75-100 mg. Pediatric patients require careful monitoring due to increased sensitivity to the drug’s effects.
Special Cases:
- Elderly Patients: Reduced doses are recommended due to age-related decline in organ function.
- Patients with Renal Impairment: Dosage adjustment may be needed due to reduced clearance.
- Patients with Hepatic Dysfunction: Dose reduction may be necessary due to impaired metabolism.
- Patients with Comorbid Conditions: Caution should be used in patients with hypertension, cardiovascular disease, hyperthyroidism, and diabetes, as adrenaline can exacerbate these conditions.
Clinical Use Cases
Dosing varies depending on the procedure. Always consult relevant medical literature for specific guidelines based on the procedure, area being anesthetized, and patient factors.
Dosage Adjustments
Dose modifications should be made on a case-by-case basis considering factors such as renal/hepatic dysfunction, patient age, body weight, and overall health status.
Side Effects
Common Side Effects:
Pale skin, burning sensation, stinging sensation, erythema (skin redness), itching, pain, petechiae.
Rare but Serious Side Effects:
Allergic reactions (cutaneous lesions, urticaria, edema, anaphylaxis), CNS toxicity (drowsiness, seizures, respiratory depression), cardiovascular effects (bradycardia, hypotension, cardiac arrest).
Long-Term Effects:
Rarely, repeated injections may cause necrosis at the injection site due to vasoconstriction.
Adverse Drug Reactions (ADR):
Anaphylactic reactions, severe cardiovascular compromise, CNS depression.
Contraindications
Hypersensitivity to any component (lidocaine, adrenaline, methylparaben, sodium metabisulphite, or other amide-type local anesthetics), use in areas supplied by end arteries (fingers, toes, nose, ears, penis), severe shock, intravenous or intrathecal administration. Should be avoided in patients allergic to parabens or ester local anesthetics.
Drug Interactions
Increased risk of hypertension with MAOIs and tricyclic antidepressants. Phenothiazines and butyrophenones may reduce adrenaline’s pressor effect. Cimetidine and beta-blockers can decrease lidocaine clearance. Use with caution in patients taking Class III antiarrhythmics (e.g., amiodarone).
Pregnancy and Breastfeeding
Pregnancy Category B for lidocaine; adrenaline’s safety is uncertain. Lidocaine is excreted in breast milk in small amounts. Use caution during pregnancy and breastfeeding, weighing risks and benefits.
Drug Profile Summary
See above sections.
Popular Combinations
This combination itself is a popular formulation.
Precautions
Screen for allergies, cardiovascular disease, hyperthyroidism, and diabetes. Reduced doses for elderly, debilitated, and acutely ill patients. Aspirate before injection to avoid intravascular administration. Avoid use in end-arterial areas.
FAQs (Frequently Asked Questions)
A: See Dosage section above.
Q2: How does adrenaline affect lidocaine’s action?
A: Adrenaline prolongs the duration of anesthesia and reduces bleeding.
Q3: What are the serious side effects to watch out for?
A: Allergic reactions, cardiovascular effects (e.g., hypotension, bradycardia), and CNS toxicity (e.g., drowsiness, seizures).
Q4: Can this combination be used in pregnant women?
A: Use with caution. Weigh benefits against potential risks to the fetus. Consult specialist if necessary.
Q5: What are the contraindications to using this drug?
A: Hypersensitivity to any component, use in end-arterial areas, severe shock.
Q6: How is this medication administered?
A: By injection, typically subcutaneously or locally.
Q7: Does this combination interact with other medications?
A: Yes. See Drug Interactions section.
Q8: Are there any special considerations for pediatric patients?
A: Yes. Dosage adjustments are essential based on age and weight. Children are more susceptible to toxicity.
A: They act as preservatives.
