PSI Pharmacology & Therapeutics 4 — Questions and Answers
Question 1: Which drug is used to reverse opioid overdose?
- Naloxone (Correct answer)
- Flumazenil
- Neostigmine
- Protamine
Correct answer: Naloxone
Naloxone is a competitive opioid receptor antagonist with high affinity for mu-receptors. IV/IM/intranasal naloxone rapidly reverses respiratory depression, sedation and miosis of opioid overdose.
Question 2: Proton pump inhibitors (PPIs) like omeprazole work by:
- Irreversibly inhibiting H+/K+ ATPase in gastric parietal cells (Correct answer)
- Blocking H2 histamine receptors
- Neutralising gastric acid
- Coating the stomach lining
Correct answer: Irreversibly inhibiting H+/K+ ATPase in gastric parietal cells
PPIs are prodrugs activated in the acidic canaliculi of parietal cells. Active drug covalently binds and irreversibly inhibits H+/K+ ATPase (the proton pump), suppressing acid secretion.
Question 3: Which antibiotic class acts by inhibiting bacterial protein synthesis at the 30S ribosomal subunit?
- Aminoglycosides (Correct answer)
- Macrolides
- Chloramphenicol
- Linezolid
Correct answer: Aminoglycosides
Aminoglycosides (e.g., gentamicin) bind the 30S ribosomal subunit, causing misreading of mRNA and production of aberrant proteins, leading to bacterial cell death.
Question 4: Calcium gluconate is urgently required in hyperkalaemia to:
- Stabilise cardiac membrane potential (Correct answer)
- Lower potassium levels directly
- Shift potassium into cells
- Enhance renal potassium excretion
Correct answer: Stabilise cardiac membrane potential
Calcium gluconate rapidly antagonises the effect of high potassium on cardiac membrane excitability, preventing arrhythmias. It works within minutes but does not lower potassium.
Question 5: Which drug is a direct oral anticoagulant (DOAC) that inhibits thrombin (factor IIa)?
- Dabigatran (Correct answer)
- Rivaroxaban
- Apixaban
- Edoxaban
Correct answer: Dabigatran
Dabigatran is a direct thrombin inhibitor. Its antidote is idarucizumab. The other DOACs listed inhibit factor Xa.
Question 6: Long-term corticosteroid use most commonly causes which adverse effect on bone?
- Osteoporosis (Correct answer)
- Osteosclerosis
- Osteonecrosis of jaw
- Paget's disease
Correct answer: Osteoporosis
Corticosteroids reduce osteoblast activity and increase osteoclast activity, suppressing bone formation and accelerating resorption, leading to osteoporosis. Bisphosphonates are co-prescribed prophylactically.
PSI Pharmacology & Therapeutics 4
Which drug is used to reverse opioid overdose?