PSI Pharmacology & Therapeutics 2 — Questions and Answers
Question 1: Which drug class is used as first-line for acute migraine attacks?
- Triptans (5-HT1B/1D agonists) (Correct answer)
- Opioids
- Beta-blockers
- Sodium valproate
Correct answer: Triptans (5-HT1B/1D agonists)
Triptans (e.g., sumatriptan) selectively activate 5-HT1B/1D receptors causing cerebral vasoconstriction and inhibiting neuropeptide release, aborting migraine attacks.
Question 2: Which antibacterial mechanism does penicillin use?
- Inhibition of bacterial cell wall synthesis (Correct answer)
- Inhibition of protein synthesis
- DNA gyrase inhibition
- Cell membrane disruption
Correct answer: Inhibition of bacterial cell wall synthesis
Penicillin irreversibly binds penicillin-binding proteins (PBPs), inhibiting cross-linking of peptidoglycan in the bacterial cell wall, leading to osmotic lysis of the bacterium.
Question 3: Selective serotonin reuptake inhibitors (SSRIs) treat depression by:
- Blocking the serotonin transporter (SERT) (Correct answer)
- Blocking monoamine oxidase
- Inhibiting serotonin receptors
- Increasing serotonin synthesis
Correct answer: Blocking the serotonin transporter (SERT)
SSRIs block SERT, preventing reuptake of serotonin from the synapse, thereby increasing synaptic serotonin concentration and enhancing serotonergic neurotransmission.
Question 4: Which diuretic is potassium-sparing and acts by blocking aldosterone receptors?
- Spironolactone (Correct answer)
- Furosemide
- Bendroflumethiazide
- Acetazolamide
Correct answer: Spironolactone
Spironolactone competitively antagonises aldosterone receptors in the collecting duct, reducing sodium reabsorption and potassium excretion. It is used in heart failure and hyperaldosteronism.
Question 5: Atorvastatin lowers LDL cholesterol primarily by:
- Inhibiting HMG-CoA reductase in the liver (Correct answer)
- Binding bile acids in the gut
- Activating lipoprotein lipase
- Inhibiting cholesterol absorption
Correct answer: Inhibiting HMG-CoA reductase in the liver
Statins inhibit HMG-CoA reductase, the rate-limiting enzyme in hepatic cholesterol synthesis. This upregulates LDL receptors, increasing LDL clearance from blood.
Question 6: Which drug is the antidote for paracetamol (acetaminophen) overdose?
- N-acetylcysteine (NAC) (Correct answer)
- Flumazenil
- Naloxone
- Activated charcoal alone
Correct answer: N-acetylcysteine (NAC)
NAC replenishes hepatic glutathione, which conjugates the toxic metabolite NAPQI (produced by CYP2E1 during paracetamol overdose), preventing liver damage.
PSI Pharmacology & Therapeutics 2
Which drug class is used as first-line for acute migraine attacks?