MFDS Human Disease and Pharmacology 2

Question 1

A patient with chronic kidney disease (eGFR 20 mL/min) requires a dental prescription for pain relief. Which analgesic is contraindicated and what is the recommended alternative?

Accepted Answer

NSAIDs (e.g., ibuprofen) are contraindicated as they reduce renal blood flow and can precipitate acute kidney injury; paracetamol is the recommended first-line analgesic

Answer

NSAIDs are contraindicated in patients with significant renal impairment (eGFR <30 mL/min) because they inhibit prostaglandin-mediated renal blood flow regulation, which can precipitate acute kidney injury, fluid retention, and hyperkalaemia. Paracetamol is the first-line analgesic in renal impairment as it is hepatically metabolised. If stronger analgesia is needed, codeine can be used with caution (reduced doses) as its metabolites accumulate in renal failure.

Question 2

What is the significance of an INR result for a patient taking warfarin, and what is the generally accepted safe range for dental extractions?

Accepted Answer

INR measures the degree of anticoagulation; dental extractions can generally be performed safely if the INR is 4.0 or below, with local haemostatic measures

Answer

The INR (International Normalised Ratio) measures the degree of anticoagulation with warfarin, with a normal value of approximately 1.0. For dental extractions, current UK guidelines recommend that procedures can be performed in primary care if the INR is stable and ≤4.0, checked within 24-72 hours before the procedure. Local haemostatic measures (suturing, oxidised cellulose, tranexamic acid mouthwash) should be used. Warfarin should NOT be stopped or reduced for dental procedures due to thromboembolic risk.

Question 3

A patient with a history of asthma experiences an acute asthma attack during dental treatment. What is the appropriate emergency management in the dental surgery?

Accepted Answer

Sit the patient upright, administer salbutamol 100 mcg via spacer (2-10 puffs), give high-flow oxygen, and call 999 if not responding

Answer

For acute asthma in the dental surgery: sit the patient upright (improves ventilation); administer salbutamol via a metered dose inhaler with a large-volume spacer (2 puffs initially, up to 10 puffs); give high-flow oxygen (15 L/min via face mask); and call 999 if there is no improvement, signs of severe/life-threatening attack (inability to complete sentences, SpO2 <92%, silent chest, cyanosis). Nebulised salbutamol 5 mg should be administered if available.

Question 4

Which hepatitis virus is most commonly transmitted through needlestick injuries in dental practice, and what is the post-exposure prophylaxis protocol?

Accepted Answer

Hepatitis B — post-exposure prophylaxis includes hepatitis B immunoglobulin (HBIG) and/or accelerated hepatitis B vaccination course if the recipient is not immune

Answer

Hepatitis B virus (HBV) is the most transmissible bloodborne virus through needlestick injury, with a transmission rate of approximately 6-30% from HBeAg-positive sources (compared to 1.8% for HCV and 0.3% for HIV). Post-exposure management includes immediate wound care, risk assessment, and for non-immune recipients: hepatitis B immunoglobulin (HBIG) ideally within 48 hours plus an accelerated vaccination course. All dental healthcare workers should be vaccinated and have confirmed immunity (anti-HBs ≥10 mIU/mL).

Question 5

A patient taking a selective serotonin reuptake inhibitor (SSRI) antidepressant requires dental treatment. What is the most clinically significant drug interaction to be aware of?

Accepted Answer

SSRIs inhibit platelet aggregation, increasing the risk of post-operative bleeding, and there is a potential interaction with tramadol increasing the risk of serotonin syndrome

Answer

SSRIs (e.g., fluoxetine, sertraline, citalopram) inhibit serotonin reuptake in platelets, impairing platelet aggregation and increasing bleeding risk, particularly when combined with NSAIDs or aspirin. Additionally, tramadol (sometimes prescribed for dental pain) combined with SSRIs can precipitate serotonin syndrome — a potentially life-threatening condition with agitation, hyperthermia, and muscle rigidity. Paracetamol with codeine is a safer analgesic choice for these patients.

MFDS Part 1 Practice Test

MFDS Part 1 Practice Test

MFDS Human Disease and Pharmacology 2