NBDE Pharmacology and Pain Control 5 — Questions and Answers
Question 1: Which local anesthetic is MOST appropriate for a patient with documented allergy to amide-type local anesthetics?
- Lidocaine
- Bupivacaine
- Procaine (Correct answer)
- Mepivacaine
Correct answer: Procaine
Procaine is an ester-type local anesthetic with a different chemical structure than amides, making it an alternative when true amide allergy is confirmed.
Question 2: The phenomenon of tachyphylaxis with local anesthetics refers to:
- Increased duration of action with repeated injections
- Decreased effectiveness with repeated injections in short succession (Correct answer)
- Systemic toxicity from cumulative dosing
- Allergy that develops after multiple exposures
Correct answer: Decreased effectiveness with repeated injections in short succession
Tachyphylaxis is a progressive decrease in local anesthetic effect with repeated injections, partly due to local tissue acidosis reducing the free base available to cross nerve membranes.
Question 3: Which drug is the opioid antagonist of choice for reversing respiratory depression caused by opioid overdose?
- Flumazenil
- Naltrexone
- Naloxone (Correct answer)
- Buprenorphine
Correct answer: Naloxone
Naloxone is the first-line agent for acute opioid-induced respiratory depression due to its rapid onset and competitive antagonism at mu-opioid receptors.
Question 4: Ketorolac is preferred over other NSAIDs for short-term postoperative pain because it:
- Can be administered parenterally for potent analgesia (Correct answer)
- Has a longer half-life than other NSAIDs
- Is COX-2 selective and thus gastric-safe
- Does not inhibit platelet aggregation
Correct answer: Can be administered parenterally for potent analgesia
Ketorolac is unique among NSAIDs in having an injectable formulation that provides opioid-comparable analgesia for acute postoperative pain without opioid side effects.
Question 5: In a patient with poorly controlled hypertension, the maximum recommended epinephrine dose per dental appointment is:
- 0.018 mg (2 cartridges of 1:100,000) (Correct answer)
- 0.04 mg
- 0.2 mg
- No restriction is needed
Correct answer: 0.018 mg (2 cartridges of 1:100,000)
The AHA recommends limiting epinephrine to 0.04 mg (approximately two cartridges of 1:100,000) per appointment in patients with significant cardiovascular disease or uncontrolled hypertension.
Question 6: Which property of local anesthetics determines their intrinsic potency?
- pKa
- Protein binding
- Lipid solubility (Correct answer)
- Degree of ionization at tissue pH
Correct answer: Lipid solubility
Lipid solubility determines the ability of a local anesthetic to penetrate the lipid-rich nerve membrane, directly correlating with anesthetic potency.
Question 7: Tramadol is considered atypical among analgesics because its mechanism includes:
- Selective COX-2 inhibition and weak mu-agonism
- Mu-opioid receptor agonism and monoamine reuptake inhibition (Correct answer)
- GABA-A receptor potentiation and kappa-opioid agonism
- NMDA antagonism and serotonin release only
Correct answer: Mu-opioid receptor agonism and monoamine reuptake inhibition
Tramadol acts both as a weak mu-opioid receptor agonist and as a serotonin/norepinephrine reuptake inhibitor, giving it a dual analgesic mechanism.
NBDE Pharmacology and Pain Control 5
Which local anesthetic is MOST appropriate for a patient with documented allergy to amide-type local anesthetics?