NBDE Pharmacology and Therapeutics 4 — Questions and Answers
Question 1: Which drug used for conscious sedation in dentistry works by antagonizing histamine H1 receptors AND producing anticholinergic effects?
- Midazolam
- Hydroxyzine (Correct answer)
- Diazepam
- Triazolam
Correct answer: Hydroxyzine
Hydroxyzine is an antihistamine with anticholinergic and sedative properties commonly used for preoperative anxiolysis in dental settings.
Question 2: Nitrous oxide produces analgesia primarily by which mechanism?
- GABA-A receptor potentiation in the limbic system
- Endogenous opioid peptide release and NMDA receptor antagonism (Correct answer)
- Serotonin reuptake inhibition in the dorsal raphe nucleus
- Voltage-gated sodium channel blockade in peripheral nerves
Correct answer: Endogenous opioid peptide release and NMDA receptor antagonism
Nitrous oxide activates endogenous opioid pathways and inhibits NMDA receptors, contributing to its analgesic and anxiolytic properties.
Question 3: A diabetic patient on metformin requires oral surgery under general anesthesia. What is the primary concern regarding metformin perioperatively?
- Risk of hypoglycemia during fasting
- Risk of lactic acidosis if renal perfusion is compromised (Correct answer)
- Interference with neuromuscular blocking agents
- Increased bleeding due to platelet inhibition
Correct answer: Risk of lactic acidosis if renal perfusion is compromised
Metformin is associated with lactic acidosis when renal function is compromised, a risk that increases during surgery due to hemodynamic changes and contrast use.
Question 4: Which drug is the treatment of choice for acute anaphylaxis occurring in the dental office?
- Diphenhydramine 50 mg IV
- Epinephrine 0.3 mg IM (1:1,000) (Correct answer)
- Hydrocortisone 100 mg IV
- Albuterol inhaler 2 puffs
Correct answer: Epinephrine 0.3 mg IM (1:1,000)
Intramuscular epinephrine into the anterolateral thigh is the first-line treatment for anaphylaxis due to its rapid reversal of vasodilation and bronchoconstriction.
Question 5: Which antifungal drug used for oral candidiasis inhibits ergosterol synthesis by blocking lanosterol 14-alpha-demethylase?
- Nystatin
- Fluconazole (Correct answer)
- Amphotericin B
- Griseofulvin
Correct answer: Fluconazole
Fluconazole inhibits fungal CYP450 enzyme lanosterol 14-alpha-demethylase, blocking ergosterol synthesis and disrupting fungal cell membrane integrity.
Question 6: Chlorhexidine gluconate used as an oral rinse works primarily by which mechanism?
- Inhibiting bacterial DNA gyrase
- Disrupting bacterial cell membranes and precipitating cytoplasmic contents (Correct answer)
- Blocking bacterial protein synthesis at the 30S ribosomal subunit
- Chelating calcium ions required for biofilm formation
Correct answer: Disrupting bacterial cell membranes and precipitating cytoplasmic contents
Chlorhexidine is a cationic bisguanide that binds to negatively charged bacterial cell membranes, causing leakage of cellular contents and bactericidal activity.
Question 7: A patient taking bisphosphonates for osteoporosis requires a tooth extraction. The MOST significant concern is:
- Increased risk of local anesthetic toxicity
- Medication-related osteonecrosis of the jaw (MRONJ) (Correct answer)
- Prolonged bleeding time from platelet inhibition
- Drug-induced xerostomia impairing wound healing
Correct answer: Medication-related osteonecrosis of the jaw (MRONJ)
Bisphosphonates suppress osteoclast activity and reduce bone vascularity, predisposing patients to MRONJ following dentoalveolar surgery.
NBDE Pharmacology and Therapeutics 4
Which drug used for conscious sedation in dentistry works by antagonizing histamine H1 receptors AND producing anticholinergic effects?