Patient Counselling & Drug Interactions Flashcards
6 cards from real PSI practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Patient Counselling & Drug Interactions flashcards as text
Which counselling point is most important for a patient starting a new SSRI for depression?
Answer: Antidepressant effect takes 2–4 weeks — continue even if no immediate improvement
SSRIs take 2–4 weeks for full antidepressant effect. Early discontinuation is a major cause of treatment failure. Patients must be counselled to persist through initial side effects and not expect immediate results.
A patient asks why they must avoid grapefruit juice with their simvastatin. The pharmacist explains:
Answer: Grapefruit inhibits CYP3A4 in the intestinal wall, raising simvastatin plasma levels and increasing myopathy risk
Grapefruit contains furanocoumarins that irreversibly inhibit intestinal CYP3A4, increasing oral bioavailability of simvastatin. This raises plasma levels, increasing the risk of myopathy and rhabdomyolysis.
Which drug interaction mechanism underlies the interaction between antacids and fluoroquinolone antibiotics?
Answer: Chelation — antacid cations (Al3+, Mg2+) complex with fluoroquinolones reducing oral absorption
Divalent and trivalent metal cations form insoluble chelates with fluoroquinolones (and tetracyclines), preventing absorption. Fluoroquinolones should be taken 2 hours before or 6 hours after antacids.
A patient on phenytoin is started on fluconazole. Which outcome should the pharmacist anticipate?
Answer: Increased phenytoin levels (risk of toxicity) — fluconazole inhibits CYP2C9
Fluconazole is a potent CYP2C9 inhibitor. Phenytoin is primarily metabolised by CYP2C9. Combination leads to significantly elevated phenytoin levels, risking ataxia, nystagmus and diplopia.
Which patient counselling approach best ensures medication adherence in a patient with low health literacy?
Answer: Simple verbal instructions with demonstrate-and-return demonstration, written pictogram leaflets
Low health literacy requires plain language, demonstration, teach-back and visual aids. Complex written materials are ineffective. Combination verbal and pictogram approaches significantly improve comprehension.
Which drug interaction between methotrexate and NSAIDs is clinically significant?
Answer: NSAIDs reduce renal methotrexate clearance, causing toxicity (mucositis, myelosuppression)
NSAIDs inhibit prostaglandin-mediated renal blood flow, reducing GFR and methotrexate excretion. This can cause severe, life-threatening methotrexate toxicity even at low weekly rheumatological doses.