ORE Part 1 Pharmacology in Dentistry 3 — Questions and Answers
Question 1: What is the mechanism of corticosteroid action in reducing post-surgical swelling?
- Inhibit phospholipase A2 (via lipocortin) preventing arachidonic acid release, reducing both prostaglandin and leukotriene production — potent anti-inflammatory effect (Correct answer)
- Block COX-2 only
- Directly reduce bacterial load
- Reduce pain by opioid pathway activation
Correct answer: Inhibit phospholipase A2 (via lipocortin) preventing arachidonic acid release, reducing both prostaglandin and leukotriene production — potent anti-inflammatory effect
Corticosteroids (e.g., dexamethasone) induce lipocortin production, which inhibits phospholipase A2. This blocks the release of arachidonic acid, preventing the synthesis of both prostaglandins and leukotrienes, providing broader anti-inflammatory effects than NSAIDs.
Question 2: What is the advantage of nystatin over fluconazole for treating oral candidiasis?
- Nystatin is not absorbed systemically and acts topically, avoiding drug interactions (e.g., with warfarin, statins) while fluconazole is systemic and has significant interactions (Correct answer)
- Nystatin has a broader antifungal spectrum
- Fluconazole can only be used topically
- Nystatin is more potent than fluconazole
Correct answer: Nystatin is not absorbed systemically and acts topically, avoiding drug interactions (e.g., with warfarin, statins) while fluconazole is systemic and has significant interactions
Nystatin (polyene antifungal) acts locally in the mouth without systemic absorption. Fluconazole (triazole) is systemic — it inhibits CYP enzymes and has clinically important interactions with warfarin, statins, and other drugs.
Question 3: What opioid is commonly prescribed for moderate-to-severe dental pain?
- Codeine phosphate (30–60 mg) combined with paracetamol, or dihydrocodeine as alternatives in UK primary dental care (Correct answer)
- Morphine sulphate as first-line
- Fentanyl patches
- Heroin (diamorphine) in hospital only
Correct answer: Codeine phosphate (30–60 mg) combined with paracetamol, or dihydrocodeine as alternatives in UK primary dental care
In UK primary dental care, codeine phosphate (mild opioid) combined with paracetamol is used for moderate dental pain. Stronger opioids are reserved for hospital settings or specific circumstances under specialist care.
Question 4: A patient is prescribed tetracycline for an oral infection. What dental concern must be discussed?
- Tetracyclines cause permanent yellow-brown staining of developing teeth — contraindicated in pregnancy, breastfeeding, and children under 12 (Correct answer)
- No dental concerns — tetracyclines are safe at all ages
- Only causes staining in adults
- Staining only occurs with prolonged use over 5 years
Correct answer: Tetracyclines cause permanent yellow-brown staining of developing teeth — contraindicated in pregnancy, breastfeeding, and children under 12
Tetracyclines chelate calcium in developing dental hard tissues, causing intrinsic yellow-brown staining and occasionally hypoplasia. They are absolutely contraindicated under 12 years, in pregnancy, and during breastfeeding.
Question 5: What is the significance of prescribing erythromycin with a patient taking warfarin?
- Erythromycin inhibits CYP3A4 causing increased warfarin levels, raising INR and bleeding risk — requires INR monitoring and possible warfarin dose reduction (Correct answer)
- No interaction — safe to prescribe together
- Erythromycin reduces warfarin absorption only
- Only relevant if erythromycin is given intravenously
Correct answer: Erythromycin inhibits CYP3A4 causing increased warfarin levels, raising INR and bleeding risk — requires INR monitoring and possible warfarin dose reduction
Erythromycin is a moderate CYP3A4 and CYP1A2 inhibitor, reducing warfarin metabolism and elevating INR. Clinically significant bleeding risk increase means enhanced INR monitoring is required when these drugs are co-prescribed.
Question 6: What is nitrous oxide/oxygen inhalation sedation and what pharmacological property makes it suitable for dental use?
- Inhalation anxiolytic with rapid onset and offset, causing anxiolysis and mild analgesia while maintaining consciousness and protective reflexes — titrated with 30–70% N2O in O2 (Correct answer)
- A general anaesthetic equivalent to IV propofol
- Only used for surgical procedures lasting >2 hours
- Provides complete analgesia equivalent to local anaesthetic
Correct answer: Inhalation anxiolytic with rapid onset and offset, causing anxiolysis and mild analgesia while maintaining consciousness and protective reflexes — titrated with 30–70% N2O in O2
Nitrous oxide (30–70% in oxygen) provides conscious sedation — anxiolysis, mild analgesia, and euphoria with rapid onset (2–3 min) and fast recovery (5–10 min after O2 flush). It maintains consciousness and protective reflexes, making it ideal for dental anxious patients.
ORE Part 1 Pharmacology in Dentistry 3
What is the mechanism of corticosteroid action in reducing post-surgical swelling?