ORE Part 1 Pharmacology — Questions and Answers
Question 1: What is the maximum recommended dose of lidocaine with 1:80,000 adrenaline for a 70kg adult?
- 3.0mg/kg (210mg)
- 4.4mg/kg (308mg) (Correct answer)
- 7.0mg/kg (490mg)
- 2.0mg/kg (140mg)
Correct answer: 4.4mg/kg (308mg)
The maximum recommended dose of lidocaine with adrenaline (epinephrine) is 4.4mg/kg (or 7.0mg/kg in some older references, though 4.4mg/kg is the widely accepted GDC standard), up to an absolute maximum of 500mg. Each 2.2ml cartridge of 2% lidocaine contains 44mg, so a 70kg adult can receive approximately 7 cartridges.
Question 2: Which analgesic is contraindicated in a patient with a history of aspirin-sensitive asthma?
- Paracetamol
- Codeine
- Ibuprofen (Correct answer)
- Tramadol
Correct answer: Ibuprofen
NSAIDs such as ibuprofen are contraindicated in aspirin-sensitive asthma (Samter's triad: asthma, nasal polyps, and aspirin sensitivity) because they inhibit cyclooxygenase, shunting arachidonic acid metabolism towards leukotriene production, which can trigger severe bronchospasm.
Question 3: A patient taking metronidazole for a dental infection should be warned about interaction with which substance?
- Caffeine
- Alcohol (Correct answer)
- Dairy products
- Grapefruit juice
Correct answer: Alcohol
Metronidazole inhibits aldehyde dehydrogenase, causing a disulfiram-like reaction when alcohol is consumed. Patients experience nausea, vomiting, flushing, and tachycardia. Patients should be advised to avoid alcohol during treatment and for 48 hours after completing the course.
Question 4: Which antibiotic is the first-line choice for acute dental infection in a penicillin-allergic patient in the UK?
- Erythromycin
- Clindamycin
- Metronidazole (Correct answer)
- Ciprofloxacin
Correct answer: Metronidazole
According to the BNF and FGDP guidelines, metronidazole 400mg three times daily for 5 days is the first-line alternative for acute dental infections when amoxicillin cannot be used due to penicillin allergy. It is effective against the predominantly anaerobic flora of dental abscesses.
Question 5: What is the mechanism of action of articaine that makes it unique among dental local anaesthetics?
- It is an ester-type local anaesthetic
- It contains a thiophene ring allowing enhanced tissue diffusion (Correct answer)
- It does not require a vasoconstrictor
- It works on calcium channels rather than sodium channels
Correct answer: It contains a thiophene ring allowing enhanced tissue diffusion
Articaine is unique among amide local anaesthetics because it contains a thiophene ring instead of a benzene ring, which increases its lipid solubility and tissue penetration. This property allows buccal infiltration of articaine to be effective for mandibular molars, potentially avoiding the need for an IAN block in some cases.
Question 6: A patient on long-term prednisolone 10mg daily requires a dental extraction. What consideration is important regarding steroid supplementation?
- No supplementation is needed for minor oral surgery
- The patient should double their dose for 24 hours (Correct answer)
- The patient should stop steroids 48 hours before
- Intravenous hydrocortisone 100mg is always required
Correct answer: The patient should double their dose for 24 hours
For patients on long-term steroids undergoing minor dental surgery, current guidance recommends doubling the usual daily dose on the day of treatment (or the morning of the procedure) to cover the adrenal stress response. For major surgery, IV hydrocortisone may be needed. Steroids should never be abruptly stopped.
ORE Part 1 Pharmacology
What is the maximum recommended dose of lidocaine with 1:80,000 adrenaline for a 70kg adult?