Articaine Local Anesthetic Overview

Articaine

• Articaine is a hybrid molecule with both amide and ester properties.
• It's 1.5 times more potent than lidocaine, but has similar toxicity.
• It's the only amide-type local anesthetic with a thiophene group, which enhances lipid solubility for better tissue penetration.
• It's metabolized in both plasma and liver, unlike other amides.
• It's excreted via the kidneys, with about 5% to 10% unchanged.
• It has a vasodilating effect similar to lidocaine.
• Available in 4% concentration, it has an onset ranging from 1-2 minutes for infiltration and 2-3 minutes for blocks.
• Duration with 1:100,000 epinephrine: 60-75 minutes for pulpal, 180-360 minutes for soft tissue.
• Duration with 1:200,000 epinephrine: 45-60 minutes for pulpal, 120-300 minutes for soft tissue.
• Maximum recommended dose: 7.0 mg/kg body weight.
• Pregnancy classification: C (not safe).
• Side Effect: Methemoglobinemia.
• Contraindication: Idiopathic or congenital methemoglobinemia, cardiac & respiratory failure, allergy to sulfite-containing drugs.

Bupivacaine

• Bupivacaine is a long-acting amide local anesthetic.
• It's 4 times more potent than lidocaine.
• Available in 0.5% concentration with 1:100,000 or 1:200,000 epinephrine.
• Indications: Lengthy procedures (oral surgery, implants, periodontics), postoperative pain management.
• Contraindications: Physically & mentally disabled children, patients with cardiovascular issues.
• Pregnancy classification: C (not safe).

Topical Anesthetics

• Intact skin is a barrier to anesthetic diffusion.
• Mucous membranes and injured skin allow topical anesthetics to reach nerve endings.
• Topical anesthesia is effective only on surface tissues (2-3 mm).
• More concentrated forms are used topically (5% or 10% lidocaine) compared to injection (2%).
• Common Topical Agents: Benzocaine, Dyclonine hydrochloride, EMLA, Lidocaine.
• Benzocaine 20%: Ester-type, poorly water-soluble, providing prolonged action, not suitable for injection.
• Dyclonine Hydrochloride: Ketone derivative, suitable for patients allergic to common anesthetics.

EMLA (Eutectic Mixture of Local Anesthetics)

• Contains 2.5% Lidocaine and 2.5% Prilocaine.
• Emulsion with eutectic mixture of lidocaine and prilocaine in a 1:1 ratio.
• Works on intact skin.
• Applied 1 hour prior to procedure.
• Contraindications: Congenital or idiopathic methemoglobinemia, infants younger than 12 months on methemoglobin-inducing agents, known sensitivity to amide-type anesthetics.

Vasoconstrictors

• Classifications:
  • Based on Chemical Structure: Catecholamines (epinephrine, norepinephrine, levonordefrin, isoproterenol, dopamine) and Noncatecholamines (amphetamine, methamphetamine, ephedrine, hydroxyamphetamine, metaraminol, methoxamine, phenylephrine).
  • Based on Mode of Action: Directly Acting (epinephrine, norepinephrine, levonordefrin, isoproterenol, dopamine, methoxamine, phenylephrine), Indirectly Acting (amphetamine, methamphetamine, hydroxyamphetamine, tyramine), Mixed Acting (metaraminol, ephedrine).
• Action of Vasoconstrictors: Decrease blood flow, slow LA absorption into cardiovascular system, decrease risk of toxicity, increase duration of action, decrease bleeding (hemostasis).
• Adrenergic Receptors: Alpha (α) receptors cause vasoconstriction, Beta (β) receptors cause vasodilation, bronchodilation, and cardiac stimulation.

Epinephrine

• Mode of action: Directly on alpha (α) and beta (β) adrenergic receptors.
• Systemic Effects: Increased heart rate and cardiac output, increased systolic blood pressure, vasoconstriction of smaller arterioles, bronchodilation, not a potent CNS stimulant, increased oxygen consumption, glycogenolysis (increased blood sugar).
• Clinical Applications: Anaphylaxis, status asthmaticus, cardiac arrest, vasoconstrictor in local anesthetics, mydriasis.
• ASA Classification: System for assessing patient's preoperative physical status.
• Recommended Maximum Dosages:
  • Normal Healthy Patient (ASA I): 1:50,000 (5.5 carpules), 1:100,000 (11 carpules), 1:200,000 (22 carpules).
  • Clinically Significant CVS Disease (ASA III or IV): 1:50,000 (1 carpul), 1:100,000 (2 carpules), 1:200,000 (4 carpules).

Levonordefrin

• Mode of action: Primarily through direct α-receptor stimulation (75%), with some β activity (25%).
• Systemic Actions: Less cardiac and CNS stimulation compared to epinephrine.
• Side Effects and Overdose: Similar to epinephrine but less severe. Higher doses can cause hypertension, ventricular tachycardia, and anginal episodes in patients with coronary artery insufficiency.
• Clinical Applications: Vasoconstrictor in local anesthetics.
• Maximum Doses: 1 mg per appointment for all patients (1:20,000 dilution - 11 cartridges).

Selection of Vasoconstrictors

• Factors considered: Length of procedure, need for hemostasis, postoperative pain control, patient's medical status.

Contraindications of Vasoconstrictors

• Benefits and risks of including vasoconstrictors should be weighed against using plain anesthetic solutions.
• Specific groups: Patients with significant cardiovascular disease (ASA class 3 and 4), patients with thyroid dysfunction, diabetes, sulfite sensitivity, patients on MAO inhibitors or tricyclic antidepressants.

Calculating Maximum Carpules (Cartridges) Per Appointment

• 2% Mepivacaine with Epi 1:100,000 (red color): (Body weight x 6.6 mg/kg) / 36 mg/cartridge
• 3% Mepivacaine without Epi (green color): (Body weight x 6.6 mg/kg) / 54 mg/cartridge
• 4% Articaine with Epi (blue color): (Body weight x 7 mg/kg) / 72 mg/cartridge

This quiz covers the essential aspects of Articaine, a potent local anesthetic with unique properties. Learn about its metabolism, dosage, effects, and clinical considerations. Ideal for dental professionals seeking to deepen their understanding of this hybrid anesthetic.