Clinical Pharmacology Flashcards

A patient taking simvastatin is prescribed clarithromycin for a respiratory infection. What is the primary concern?

Answer: Clarithromycin inhibits CYP3A4, dramatically increasing simvastatin levels and the risk of myopathy/rhabdomyolysis

Clarithromycin is a potent CYP3A4 inhibitor; co-administration with simvastatin (a CYP3A4 substrate) raises statin plasma levels, greatly increasing the risk of myopathy and rhabdomyolysis.

Which receptor type mediates the bronchodilator effect of salbutamol (albuterol)?

Answer: Beta-2 adrenergic receptors in bronchial smooth muscle

Salbutamol is a selective beta-2 adrenergic agonist; its binding to beta-2 receptors in bronchial smooth muscle activates adenylyl cyclase, increasing cAMP and causing bronchodilation.

What is the mechanism of action of metformin in type 2 diabetes?

Answer: Activates AMPK to reduce hepatic glucose production and improve insulin sensitivity

Metformin primarily activates AMP-activated protein kinase (AMPK), which suppresses hepatic gluconeogenesis and improves peripheral insulin sensitivity without causing hypoglycaemia.

Which adverse effect is uniquely associated with ACE inhibitors and distinguishes them from ARBs?

Answer: Dry, persistent cough caused by bradykinin accumulation

ACE inhibitors prevent the breakdown of bradykinin in the lungs; accumulation of bradykinin causes the characteristic dry, persistent cough not seen with ARBs.

What is the pharmacological basis for using atropine to treat bradycardia?

Answer: Atropine blocks muscarinic receptors, preventing acetylcholine-induced slowing of the heart rate

Atropine is a competitive muscarinic antagonist that blocks vagal (acetylcholine-mediated) slowing of the SA node, thereby increasing heart rate.

Which enzyme does aspirin irreversibly inhibit to achieve its antiplatelet effect?

Answer: Cyclooxygenase (COX-1)

Aspirin irreversibly acetylates and inhibits COX-1 in platelets, preventing thromboxane A2 synthesis and thereby inhibiting platelet aggregation for the platelet's entire lifespan.