PLAB 1 Pharmacology and Therapeutics

Question 1

A patient is started on warfarin for atrial fibrillation. According to NICE guidelines, what is the target INR range for non-valvular AF?

Accepted Answer

2.0-3.0

Answer

The target INR for warfarin in non-valvular atrial fibrillation is 2.0-3.0. A higher range (2.5-3.5) is used for mechanical heart valves. DOACs (e.g., apixaban, rivarelbaan) are now recommended first-line for non-valvular AF by NICE, as they do not require INR monitoring.

Question 2

A 55-year-old man presents with an acute ST-elevation myocardial infarction (STEMI). According to NICE and UK guidelines, which combination of antiplatelet drugs should be given immediately?

Accepted Answer

Aspirin 300 mg plus a P2Y12 inhibitor (e.g., ticagrelor or clopidogrel)

Answer

UK guidelines for STEMI recommend dual antiplatelet therapy (DAPT): aspirin 300 mg loading dose plus a P2Y12 inhibitor. Ticagrelor is preferred over clopidogrel for STEMI patients undergoing primary PCI. DAPT is continued for 12 months post-MI.

Question 3

A patient on metformin 1g BD develops an eGFR of 28 mL/min. According to BNF guidelines, what should be done with the metformin?

Accepted Answer

Stop metformin — it is contraindicated when eGFR falls below 30 mL/min due to the risk of lactic acidosis

Answer

Metformin should be stopped when eGFR falls below 30 mL/min/1.73m2 due to the risk of lactic acidosis from impaired renal clearance. The dose should be reviewed when eGFR falls below 45, and reduced when below 30. An alternative glucose-lowering agent should be substituted.

Question 4

A GP is prescribing ramipril for a patient with newly diagnosed hypertension. What monitoring is required after starting an ACE inhibitor?

Accepted Answer

Renal function and electrolytes should be checked before starting and 1-2 weeks after initiation or dose change

Answer

ACE inhibitors can cause hyperkalaemia and deterioration of renal function, particularly in patients with renovascular disease. BNF and NICE recommend checking U&Es and eGFR before starting, 1-2 weeks after starting or dose increase, and periodically thereafter. A rise in creatinine >30% or fall in eGFR >25% requires specialist review.

Question 5

A patient with epilepsy controlled on sodium valproate discovers she is pregnant. What is the most important concern regarding sodium valproate in pregnancy?

Accepted Answer

Sodium valproate is a known teratogen with a 10% risk of major congenital malformations and up to 40% risk of neurodevelopmental disorders — the Pregnancy Prevention Programme must be followed

Answer

Sodium valproate is a major teratogen associated with neural tube defects, congenital malformations (10%), and neurodevelopmental disorders including autism and reduced IQ (up to 40%). The MHRA Pregnancy Prevention Programme requires two forms of contraception and annual risk acknowledgement forms for all women of childbearing potential.

PLAB 1 Practice Test

PLAB 1 Practice Test

PLAB 1 Pharmacology and Therapeutics