NBDE Pharmacology and Therapeutics 3 — Questions and Answers
Question 1: A dentist prescribes amoxicillin-clavulanate (Augmentin). What advantage does clavulanate provide?
- It crosses the blood-brain barrier more effectively
- It inhibits beta-lactamase enzymes produced by resistant bacteria (Correct answer)
- It extends the half-life of amoxicillin by reducing renal clearance
- It provides direct bactericidal activity against anaerobes
Correct answer: It inhibits beta-lactamase enzymes produced by resistant bacteria
Clavulanate is a beta-lactamase inhibitor that protects amoxicillin from enzymatic degradation by resistant organisms such as Staphylococcus aureus.
Question 2: Which opioid analgesic is MOST appropriate for moderate-to-severe dental pain in a patient with renal impairment?
- Codeine
- Morphine
- Hydromorphone (Correct answer)
- Hydrocodone with acetaminophen
Correct answer: Hydromorphone
Hydromorphone has fewer active metabolite accumulations in renal impairment compared to morphine or codeine, which accumulate toxic metabolites.
Question 3: Corticosteroids are sometimes used after oral surgery. Which adverse effect is MOST concerning with systemic use?
- Peripheral neuropathy
- Adrenal suppression (Correct answer)
- Agranulocytosis
- Hepatotoxicity
Correct answer: Adrenal suppression
Exogenous corticosteroids suppress the hypothalamic-pituitary-adrenal axis, potentially causing adrenal insufficiency upon sudden withdrawal.
Question 4: A patient is prescribed tetracycline for periodontal disease. What should the dentist counsel regarding administration?
- Take with milk to reduce GI upset
- Avoid dairy, antacids, and iron supplements within 2 hours (Correct answer)
- Take on a full stomach to improve absorption
- Avoid sunlight only in the first 48 hours
Correct answer: Avoid dairy, antacids, and iron supplements within 2 hours
Divalent and trivalent cations (Ca²⁺, Mg²⁺, Al³⁺, Fe²⁺) chelate tetracycline in the GI tract, significantly reducing oral bioavailability.
Question 5: Which mechanism explains why aspirin is avoided in children with viral infections?
- Risk of agranulocytosis from combined immune activation
- Association with Reye syndrome causing hepatic and cerebral damage (Correct answer)
- Increased risk of hemorrhagic stroke in pediatric populations
- Inhibition of viral clearance through COX-2 suppression
Correct answer: Association with Reye syndrome causing hepatic and cerebral damage
Aspirin use in children with viral illnesses (influenza, varicella) is linked to Reye syndrome, a potentially fatal hepatoencephalopathy.
Question 6: Which local anesthetic property MOST influences the speed of onset?
- Degree of protein binding
- pKa relative to tissue pH (Correct answer)
- Lipid solubility
- Molecular weight
Correct answer: pKa relative to tissue pH
The closer the pKa to physiologic pH (7.4), the greater the proportion of uncharged base available to cross the nerve membrane, accelerating onset.
Question 7: A patient taking phenytoin for epilepsy shows gingival overgrowth. Which statement about this drug-induced effect is CORRECT?
- It is dose-independent and unrelated to oral hygiene
- It is caused by reduced collagen degradation and is worsened by plaque (Correct answer)
- It results from direct toxicity to periodontal ligament cells only
- It reverses completely within one week of drug discontinuation
Correct answer: It is caused by reduced collagen degradation and is worsened by plaque
Phenytoin induces gingival fibroblast proliferation and reduces collagenase activity; poor plaque control significantly worsens the overgrowth.
NBDE Pharmacology and Therapeutics 3
A dentist prescribes amoxicillin-clavulanate (Augmentin).
What advantage does clavulanate provide?