NBDE Pharmacology and Therapeutics 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?

Accepted Answer

Lidocaine

Answer

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?

Accepted Answer

Ibuprofen

Answer

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?

Accepted Answer

A prosthetic cardiac valve

Answer

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?

Accepted Answer

Binding to ergosterol in the fungal cell membrane, causing leakage

Answer

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?

Accepted Answer

Arrange for a responsible adult to provide transportation home.

Answer

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.

NBDE - National Board Dental Examination Practice Test

NBDE - National Board Dental Examination Practice Test

NBDE Pharmacology and Therapeutics Questions and Answers