Free NDEB Pharmacology and Therapeutics Questions and Answers — Questions and Answers
Question 1: A 68-year-old male patient with a history of hypertension, well-controlled with propranolol, requires a mandibular tooth extraction. After administering a local anesthetic containing 1:100,000 epinephrine, the patient's blood pressure rises sharply, and their heart rate drops. Which of the following best explains this reaction?
- An allergic reaction to the amide anesthetic.
- Unopposed alpha-adrenergic stimulation from epinephrine. (Correct answer)
- Anesthetic solution was injected intravascularly.
- Anxiety-induced hypertensive episode.
Correct answer: Unopposed alpha-adrenergic stimulation from epinephrine.
Propranolol is a non-selective beta-blocker, meaning it blocks both beta-1 and beta-2 adrenergic receptors. When epinephrine is administered, its beta-2 mediated vasodilatory effects are blocked by propranolol, leaving the alpha-1 mediated vasoconstrictive effects unopposed. This leads to a significant increase in peripheral vascular resistance and blood pressure (hypertension), which in turn triggers a compensatory reflex bradycardia (decreased heart rate).
Question 2: A patient reports post-operative dental pain following a procedure. You recommend an over-the-counter NSAID like ibuprofen. What is the primary mechanism of action by which ibuprofen reduces pain?
- Blocking opioid receptors in the central nervous system.
- Inhibiting the reuptake of serotonin and norepinephrine.
- Preventing the synthesis of prostaglandins by inhibiting COX enzymes. (Correct answer)
- Stimulating the release of endogenous endorphins.
Correct answer: Preventing the synthesis of prostaglandins by inhibiting COX enzymes.
Nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen exert their analgesic, anti-inflammatory, and antipyretic effects primarily by inhibiting cyclooxygenase (COX) enzymes (both COX-1 and COX-2). This inhibition prevents the conversion of arachidonic acid into prostaglandins, which are key mediators of inflammation and pain at the site of tissue injury.
Question 3: According to the most recent American Heart Association (AHA) guidelines, which of the following patients requires antibiotic prophylaxis before an invasive dental procedure to prevent infective endocarditis?
- A patient with mitral valve prolapse.
- A patient with a history of rheumatic heart disease.
- A patient with a prosthetic cardiac valve. (Correct answer)
- A patient with a bicuspid aortic valve.
Correct answer: A patient with a prosthetic cardiac valve.
The American Heart Association (AHA) guidelines for the prevention of infective endocarditis have been significantly narrowed. Prophylaxis is now recommended only for patients with the highest risk of adverse outcomes. This includes patients with a prosthetic cardiac valve, a previous history of infective endocarditis, certain congenital heart diseases, and cardiac transplant recipients who develop cardiac valvulopathy. Mitral valve prolapse and rheumatic heart disease are no longer indications for routine prophylaxis.
Question 4: A patient scheduled for a simple tooth extraction reports they are taking warfarin. Their most recent INR reading, taken yesterday, was 2.8. What is the most appropriate course of action?
- Cancel the procedure and refer the patient to their physician to stop warfarin.
- Proceed with the extraction using local hemostatic measures. (Correct answer)
- Administer vitamin K to reverse the effects of warfarin before the procedure.
- Proceed with the extraction but avoid using a local anesthetic with a vasoconstrictor.
Correct answer: Proceed with the extraction using local hemostatic measures.
For patients on warfarin undergoing minor dental surgery like a simple extraction, treatment can typically proceed without interrupting their anticoagulant medication if their INR is within the therapeutic range and below 4.0. An INR of 2.8 is considered safe for this procedure. The use of local hemostatic measures (e.g., packing, sutures) is recommended to control any potential bleeding. Discontinuing warfarin increases the risk of a thromboembolic event.
Question 5: A patient who has been receiving intravenous bisphosphonate therapy for several years for the management of bone metastases is at an increased risk for which of the following adverse oral conditions, especially after a dental extraction?
- Gingival hyperplasia
- Lichen planus
- Stevens-Johnson syndrome
- Medication-related osteonecrosis of the jaw (MRONJ) (Correct answer)
Correct answer: Medication-related osteonecrosis of the jaw (MRONJ)
Medication-related osteonecrosis of the jaw (MRONJ) is a recognized adverse effect of antiresorptive therapies, including intravenous bisphosphonates. The risk is highest in patients receiving high doses for cancer-related conditions. MRONJ is characterized by exposed, necrotic bone in the maxillofacial region that persists for more than eight weeks. Invasive dental procedures, such as extractions, are a major precipitating factor.
Question 6: A patient has a documented true allergic reaction to procaine. Which of the following local anesthetics would be most appropriate to use for this patient, assuming no other allergies?
- Tetracaine
- Lidocaine (Correct answer)
- Benzocaine
- Cocaine
Correct answer: Lidocaine
Local anesthetics are classified as either esters or amides. Procaine is an ester-type anesthetic. Allergic reactions to esters are more common due to their metabolism to para-aminobenzoic acid (PABA), and cross-reactivity exists among ester anesthetics. Therefore, another ester like tetracaine, benzocaine, or cocaine should be avoided. Lidocaine is an amide-type anesthetic and does not produce PABA, making it a safe alternative in a patient with a documented ester allergy.
Free NDEB Pharmacology and Therapeutics Questions and Answers
A 68-year-old male patient with a history of hypertension, well-controlled with propranolol, requires a mandibular tooth extraction.
After administering a local anesthetic containing 1:100,000 epinephrine, the patient's blood pressure rises sharply, and their heart rate drops.
Which of the following best explains this reaction?