MJDF Pharmacology & Pain Control 2 — Questions and Answers
Question 1: Which analgesic combination is recommended by NICE for post-operative dental pain in adults without contraindications?
- Ibuprofen 400 mg + paracetamol 1 g (alternating or combined) (Correct answer)
- Codeine alone
- Opioids as first-line
- Aspirin 600 mg only
Correct answer: Ibuprofen 400 mg + paracetamol 1 g (alternating or combined)
Evidence supports the combination of an NSAID (ibuprofen 400 mg) with paracetamol 1 g for dental pain, providing superior analgesia through complementary mechanisms compared to either drug alone.
Question 2: What is the mechanism of action of NSAIDs in dental pain management?
- Inhibit COX-1 and COX-2, reducing prostaglandin synthesis at the site of inflammation (Correct answer)
- Block sodium channels like local anaesthetics
- Stimulate endorphin release
- Increase serotonin reuptake
Correct answer: Inhibit COX-1 and COX-2, reducing prostaglandin synthesis at the site of inflammation
NSAIDs (e.g., ibuprofen) inhibit cyclo-oxygenase enzymes (COX-1/COX-2), reducing prostaglandin production at sites of dental/periodontal inflammation, thereby reducing pain and swelling.
Question 3: What drug interaction must be considered when prescribing metronidazole to a dental patient?
- Metronidazole inhibits aldehyde dehydrogenase — serious interaction with alcohol (disulfiram-like reaction) (Correct answer)
- Potentiates beta-blockers
- Reduces efficacy of local anaesthetics
- Interacts with fluoride
Correct answer: Metronidazole inhibits aldehyde dehydrogenase — serious interaction with alcohol (disulfiram-like reaction)
Metronidazole inhibits alcohol metabolism, causing acetaldehyde accumulation; patients must be warned to avoid alcohol during and for 48 hours after the course due to the severe disulfiram-like reaction.
Question 4: What is the first-line antibiotic for acute dentoalveolar abscess in a non-penicillin-allergic patient?
- Amoxicillin 500 mg three times daily for 5 days (Correct answer)
- Co-amoxiclav as first-line
- Metronidazole as first-line
- Erythromycin as first-line
Correct answer: Amoxicillin 500 mg three times daily for 5 days
Amoxicillin 500 mg TDS for 5 days is the first-line antibiotic for acute dentoalveolar abscess when systemic signs are present and drainage alone is insufficient, per PHE antimicrobial guidelines.
Question 5: What is the mechanism of action of midazolam in conscious sedation?
- Positive allosteric modulator of GABA-A receptors, enhancing chloride channel opening (CNS depression) (Correct answer)
- Blocks opioid receptors
- Inhibits dopamine reuptake
- Blocks NMDA receptors
Correct answer: Positive allosteric modulator of GABA-A receptors, enhancing chloride channel opening (CNS depression)
Midazolam (a benzodiazepine) binds allosterically to GABA-A receptors, increasing frequency of chloride channel opening in response to GABA, producing anxiolysis, amnesia, and sedation.
Question 6: Which enzyme system is responsible for the rapid hepatic metabolism of midazolam?
- CYP3A4 (cytochrome P450) (Correct answer)
- MAO-A
- Glucuronidase
- Acetylcholinesterase
Correct answer: CYP3A4 (cytochrome P450)
Midazolam is extensively metabolised by CYP3A4 in the liver; inhibitors of CYP3A4 (e.g., erythromycin, fluconazole) increase midazolam plasma levels, prolonging sedation.
MJDF Pharmacology & Pain Control 2
Which analgesic combination is recommended by NICE for post-operative dental pain in adults without contraindications?