AGD Dental Pharmacology 1 — Questions and Answers
Question 1: Which local anesthetic has the longest duration of pulpal anesthesia due to its high lipid solubility and protein binding?
- Lidocaine
- Mepivacaine
- Bupivacaine (Correct answer)
- Prilocaine
Correct answer: Bupivacaine
Bupivacaine provides the longest duration of pulpal anesthesia (up to 12 hours) because of its high lipid solubility and extensive protein binding.
Question 2: Articaine is structurally unique among amide local anesthetics because it contains:
- An ester linkage in addition to the amide bond
- A thiophene ring instead of a benzene ring (Correct answer)
- A piperidine ring structure
- A methoxy-substituted benzene ring
Correct answer: A thiophene ring instead of a benzene ring
Articaine uniquely contains a thiophene ring, which increases its lipid solubility and enables enhanced diffusion through soft and hard tissues.
Question 3: The maximum recommended dose of epinephrine for a patient with significant cardiovascular disease is:
- 0.2 mg
- 0.1 mg
- 0.04 mg (Correct answer)
- 0.01 mg
Correct answer: 0.04 mg
The American Heart Association recommends limiting epinephrine to 0.04 mg (approximately 2 cartridges of 1:100,000) in patients with cardiovascular compromise.
Question 4: Which local anesthetic is most associated with methemoglobinemia when used in high doses?
- Lidocaine
- Articaine
- Bupivacaine
- Prilocaine (Correct answer)
Correct answer: Prilocaine
Prilocaine is metabolized to ortho-toluidine, which oxidizes hemoglobin to methemoglobin, particularly at high cumulative doses.
Question 5: Local anesthetics primarily prevent nerve impulse conduction by:
- Blocking voltage-gated potassium channels
- Opening chloride ion channels
- Blocking voltage-gated sodium channels (Correct answer)
- Inhibiting acetylcholine release at the synapse
Correct answer: Blocking voltage-gated sodium channels
Local anesthetics bind to and block voltage-gated sodium channels, preventing sodium influx and stopping action potential propagation along the nerve.
Question 6: Sodium bisulfite is added to local anesthetic cartridges that contain epinephrine in order to:
- Lower the pH to improve anesthetic efficacy
- Prevent bacterial contamination
- Preserve epinephrine by preventing its oxidation (Correct answer)
- Extend the shelf life of the amide anesthetic itself
Correct answer: Preserve epinephrine by preventing its oxidation
Sodium bisulfite is an antioxidant that protects epinephrine from oxidative degradation, which is why epinephrine-containing solutions have a lower pH (3.3–5.5).
Question 7: Epinephrine in local anesthetic solutions acts on which receptors to produce vasoconstriction at the injection site?
- Beta-2 adrenergic receptors only
- Muscarinic receptors
- Alpha-1 adrenergic receptors (Correct answer)
- Dopaminergic D1 receptors
Correct answer: Alpha-1 adrenergic receptors
Vasoconstriction at the injection site is mediated by alpha-1 adrenergic receptor stimulation, which prolongs anesthetic duration and reduces systemic absorption.
AGD Dental Pharmacology 1
Which local anesthetic has the longest duration of pulpal anesthesia due to its high lipid solubility and protein binding?