NBDE Pharmacology and Therapeutics Questions and Answers — Questions and Answers
Question 1: A patient with a known true allergy to procaine requires local anesthesia for a restorative procedure. Which of the following local anesthetics would be the safest to administer?
- Tetracaine
- Lidocaine (Correct answer)
- Benzocaine
- Propoxycaine
Correct answer: Lidocaine
Procaine is an ester-type local anesthetic. True allergic reactions, though rare, are more common with esters due to their metabolism to para-aminobenzoic acid (PABA), a known allergen. Cross-reactivity among ester anesthetics is common. Lidocaine is an amide-type anesthetic, which is metabolized differently and does not produce PABA, making it the safest choice as cross-reactivity between esters and amides is not expected.
Question 2: A 45-year-old patient is taking warfarin for atrial fibrillation and requires an analgesic for post-extraction pain. Which of the following medications should be avoided due to a significant drug interaction that increases the risk of bleeding?
- Acetaminophen
- Oxycodone
- Ibuprofen (Correct answer)
- Tramadol
Correct answer: Ibuprofen
Ibuprofen is a nonsteroidal anti-inflammatory drug (NSAID) that can significantly increase the risk of bleeding in patients taking warfarin. This occurs through multiple mechanisms, including inhibition of platelet aggregation and displacement of warfarin from plasma proteins, which potentiates its anticoagulant effect. Acetaminophen is generally considered a safer alternative for pain relief in these patients.
Question 3: According to the most recent American Heart Association (AHA) guidelines, which of the following cardiac conditions is considered a high-risk factor that requires antibiotic prophylaxis before an invasive dental procedure?
- Mitral valve prolapse
- A prosthetic cardiac valve (Correct answer)
- Previous coronary artery bypass graft surgery
- A cardiac pacemaker
Correct answer: A prosthetic cardiac valve
The current AHA guidelines recommend antibiotic prophylaxis for a limited group of patients at the highest risk for adverse outcomes from infective endocarditis. This group includes patients with prosthetic cardiac valves or prosthetic material used for valve repair. Mitral valve prolapse (without regurgitation), previous CABG surgery, and pacemakers are not typically indications for prophylaxis under the current, more restrictive guidelines.
Question 4: Which of the following is the primary mechanism of action for nystatin when used to treat oral candidiasis?
- Inhibiting fungal DNA gyrase
- Disrupting fungal cell wall synthesis
- Inhibiting fungal protein synthesis at the 30S ribosomal subunit
- Binding to ergosterol in the fungal cell membrane, causing leakage (Correct answer)
Correct answer: Binding to ergosterol in the fungal cell membrane, causing leakage
Nystatin is a polyene antifungal agent. Its primary mechanism of action is binding to ergosterol, a key sterol component of the fungal cell membrane. This binding creates pores or channels in the membrane, leading to increased permeability, leakage of essential intracellular contents like potassium ions, and ultimately, fungal cell death.
Question 5: A dentist prescribes triazolam for an adult patient with severe dental anxiety to be taken prior to the appointment. Which of the following is the most critical post-operative instruction for this patient?
- Avoid eating grapefruit for 24 hours after the appointment.
- Arrange for a responsible adult to provide transportation home. (Correct answer)
- Take the medication on an empty stomach for faster absorption.
- Remain in an upright position for at least 30 minutes after the procedure.
Correct answer: Arrange for a responsible adult to provide transportation home.
Triazolam is a benzodiazepine that causes significant central nervous system depression, leading to drowsiness, dizziness, amnesia, and impaired coordination. For safety, a patient who has taken triazolam must not operate a vehicle or heavy machinery. Therefore, arranging for a responsible adult to drive them to and from the appointment is a critical safety instruction.
Question 6: Which of the following is a common adverse effect associated with the use of codeine for post-operative dental pain that often limits its use?
- Nausea and vomiting (Correct answer)
- Hypertension
- Xerostomia
- Bruxism
Correct answer: Nausea and vomiting
Codeine is an opioid analgesic, and a very common side effect profile includes gastrointestinal issues. Nausea and vomiting are frequently reported and can be significant enough to cause patient non-compliance. Other common side effects include drowsiness, dizziness, and constipation.
NBDE Pharmacology and Therapeutics Questions and Answers
A patient with a known true allergy to procaine requires local anesthesia for a restorative procedure.
Which of the following local anesthetics would be the safest to administer?