Pharmacology Flashcards

What is the maximum recommended dose of lidocaine with 1:80,000 adrenaline for a 70kg adult?

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.

Which analgesic is contraindicated in a patient with a history of aspirin-sensitive asthma?

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.

A patient taking metronidazole for a dental infection should be warned about interaction with which substance?

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.

Which antibiotic is the first-line choice for acute dental infection in a penicillin-allergic patient in the UK?

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.

What is the mechanism of action of articaine that makes it unique among dental local anaesthetics?

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.

A patient on long-term prednisolone 10mg daily requires a dental extraction. What consideration is important regarding steroid supplementation?

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.