Clinical Therapeutics & BNF Guidelines Flashcards

A patient prescribed warfarin reports eating large amounts of leafy green vegetables. What effect might this have?

Answer: Reduced INR due to increased vitamin K intake

Leafy greens (e.g., spinach, kale) are rich in vitamin K, which antagonises warfarin's anticoagulant effect, reducing INR. Consistent dietary intake is advised.

Which antiepileptic drug is a potent inducer of hepatic CYP enzymes?

Answer: Carbamazepine

Carbamazepine is a potent CYP3A4 and CYP2C9 inducer, accelerating metabolism of many co-administered drugs including warfarin, OCP, and other antiepileptics.

What is the recommended action if a patient on an ACE inhibitor develops a persistent dry cough?

Answer: Switch to an angiotensin receptor blocker (ARB)

ACE inhibitor-induced cough is caused by bradykinin accumulation. Switching to an ARB (which does not affect bradykinin) resolves the cough while maintaining cardioprotective benefit.

Which vaccine is a live attenuated vaccine and thus contraindicated in immunocompromised patients?

Answer: MMR (measles, mumps, rubella)

MMR is a live attenuated vaccine and is contraindicated in severely immunocompromised individuals as it may cause vaccine-strain disease. Inactivated vaccines are safe to use.

Which drug is used as prophylaxis against Pneumocystis jirovecii pneumonia (PCP) in immunosuppressed patients?

Answer: Co-trimoxazole (trimethoprim + sulfamethoxazole)

Co-trimoxazole is first-line PCP prophylaxis in HIV patients with CD4 <200 cells/µL and other immunosuppressed patients (e.g., on high-dose corticosteroids, post-transplant).

A patient with heart failure is prescribed furosemide. Which electrolyte should be routinely monitored?

Answer: Potassium

Loop diuretics like furosemide cause significant urinary potassium loss, leading to hypokalaemia which can precipitate arrhythmias, especially in patients on digoxin.