PSI Pharmacology & Therapeutics 3

Question 1

Which inhaler technique is most important for pressurised metered dose inhalers (pMDIs)?

Accepted Answer

Slow, deep inhalation coordinated with actuation

Answer

Slow, deep inhalation coordinated with actuation maximises drug deposition in the lower airways. Fast inhalation causes impaction in the oropharynx, and a 10-second breath-hold improves deposition.

Question 2

Theophylline has a narrow therapeutic index. Which interaction significantly increases its toxicity risk?

Accepted Answer

Ciprofloxacin inhibits CYP1A2, raising theophylline levels

Answer

Ciprofloxacin is a strong CYP1A2 inhibitor. Theophylline is metabolised by CYP1A2; co-administration can double plasma levels, causing nausea, arrhythmias and seizures.

Question 3

Insulin glargine differs from human insulin because it:

Accepted Answer

Has a prolonged, peakless action lasting ~24 hours

Answer

Glargine has substitutions that create microcrystals at physiological pH, releasing insulin slowly with no pronounced peak — ideal as once-daily basal insulin.

Question 4

Which antiplatelet drug requires hepatic activation by CYP2C19 to exert its effect?

Accepted Answer

Clopidogrel

Answer

Clopidogrel is a prodrug requiring CYP2C19-mediated activation. Poor metabolisers of CYP2C19 have reduced antiplatelet effect, increasing cardiovascular risk.

Question 5

Serotonin syndrome is most likely when combining an SSRI with which other drug?

Accepted Answer

Linezolid (MAO inhibitor)

Answer

Linezolid inhibits monoamine oxidase (MAO), reducing serotonin breakdown. Combined with an SSRI, serotonin accumulates, causing hyperthermia, clonus, agitation and autonomic instability.

PSI Pharmacy Practice Test

PSI Pharmacy Practice Test

PSI Pharmacology & Therapeutics 3