KAPS Pharmacology and Therapeutics 3 — Questions and Answers
Question 1: Which antihypertensive class is first-line therapy for a hypertensive patient with diabetes and microalbuminuria?
- Thiazide diuretics
- Beta-blockers
- ACE inhibitors or ARBs (Correct answer)
- Calcium channel blockers
Correct answer: ACE inhibitors or ARBs
ACE inhibitors and ARBs reduce intraglomerular pressure and have proven nephroprotective effects in diabetic nephropathy beyond blood pressure control.
Question 2: A patient presents with bradycardia, hypotension, and hyperkalemia after a calcium channel blocker overdose. Which treatment is most appropriate?
- Digoxin to increase cardiac contractility
- High-dose insulin and dextrose to overcome calcium channel blockade (Correct answer)
- Atropine alone as sufficient treatment
- Furosemide to reduce preload
Correct answer: High-dose insulin and dextrose to overcome calcium channel blockade
High-dose insulin (hyperinsulinemia-euglycemia therapy) improves myocardial glucose utilization and is a mainstay of severe calcium channel blocker toxicity management.
Question 3: Selective serotonin reuptake inhibitors (SSRIs) are thought to exert antidepressant effects through which primary mechanism?
- Immediate inhibition of MAO-A in presynaptic terminals
- Blockade of postsynaptic 5-HT2A receptors
- Gradual desensitization of presynaptic autoreceptors following serotonin reuptake blockade (Correct answer)
- Direct agonism at 5-HT1A receptors
Correct answer: Gradual desensitization of presynaptic autoreceptors following serotonin reuptake blockade
Although SSRIs immediately block the serotonin transporter, the therapeutic delay reflects time needed for desensitization of presynaptic 5-HT1A autoreceptors, allowing sustained serotonin increases.
Question 4: Which pharmacokinetic parameter is most useful for calculating a loading dose?
- Clearance (CL)
- Half-life (t½)
- Volume of distribution (Vd) (Correct answer)
- Bioavailability (F)
Correct answer: Volume of distribution (Vd)
Loading dose = (target concentration × Vd) / F; the volume of distribution determines how much drug is needed to achieve the desired plasma level rapidly.
Question 5: A patient with gout is started on allopurinol. Which mechanism explains its urate-lowering effect?
- Competitive inhibition of urate transporter 1 (URAT1) in renal tubules
- Inhibition of xanthine oxidase, blocking uric acid synthesis (Correct answer)
- Enhanced renal filtration of urate by increasing GFR
- Chelation of uric acid in the blood
Correct answer: Inhibition of xanthine oxidase, blocking uric acid synthesis
Allopurinol and its active metabolite oxypurinol inhibit xanthine oxidase, preventing conversion of hypoxanthine and xanthine to uric acid.
Question 6: Which adverse effect is most associated with long-term corticosteroid use and is caused by suppression of the HPA axis?
- Addisonian crisis upon abrupt withdrawal (Correct answer)
- Immediate adrenal hyperplasia
- Mineralocorticoid excess causing hyponatremia
- Increased ACTH secretion causing hyperpigmentation
Correct answer: Addisonian crisis upon abrupt withdrawal
Chronic exogenous corticosteroids suppress CRH and ACTH, causing adrenal atrophy; abrupt discontinuation can precipitate an Addisonian crisis due to insufficient cortisol production.
Question 7: A patient on lithium is started on ibuprofen for arthritis pain. What interaction should be anticipated?
- Decreased lithium levels due to increased renal clearance
- Increased lithium levels due to reduced renal prostaglandin-dependent excretion (Correct answer)
- Additive CNS depression causing sedation
- No significant interaction expected
Correct answer: Increased lithium levels due to reduced renal prostaglandin-dependent excretion
NSAIDs reduce renal prostaglandin synthesis, decreasing renal blood flow and lithium clearance, potentially causing lithium toxicity.
KAPS Pharmacology and Therapeutics 3
Which antihypertensive class is first-line therapy for a hypertensive patient with diabetes and microalbuminuria?