Pharmacist Flashcards
6 cards from real DHA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Pharmacist flashcards as text
A patient taking lithium carbonate for bipolar disorder is started on a new NSAID for arthritis pain. What is the primary pharmacokinetic concern?
Answer: NSAIDs decrease renal lithium clearance, increasing lithium levels and toxicity risk
NSAIDs inhibit prostaglandin synthesis in the kidney, reducing renal blood flow and GFR, and increasing proximal tubular lithium reabsorption (along with sodium). This decreases lithium clearance and can increase serum lithium levels by 20–50%, potentially causing lithium toxicity.
In pharmaceutical compounding, what is the primary regulatory requirement that ensures a compounded preparation is suitable for patient use?
Answer: It must meet Good Manufacturing Practice (GMP) standards and be prepared under appropriate quality controls
Compounded preparations must be prepared under appropriate quality control conditions that ensure safety, potency, purity, and sterility (for sterile preparations). DHA and UAE regulations require pharmacies performing compounding to meet defined standards, and sterile compounding requires additional environmental controls (ISO classified cleanrooms).
A pharmacist receives a prescription for warfarin 5mg once daily. The patient mentions they started taking St. John's Wort (a herbal supplement) for depression. What is the pharmacist's appropriate response?
Answer: Counsel the patient and notify the prescriber — St. John's Wort is a potent CYP450 inducer that reduces warfarin levels and increases stroke risk
St. John's Wort (Hypericum perforatum) is a potent inducer of CYP3A4 and P-glycoprotein. It significantly increases warfarin metabolism, reducing warfarin plasma levels and anticoagulant effect. Patients on warfarin (or other CYP3A4-metabolized drugs) must avoid St. John's Wort. The pharmacist should counsel the patient and alert the prescriber.
Which of the following best describes the 'first-pass effect' in pharmacokinetics?
Answer: The pre-systemic metabolism of an orally administered drug by the intestinal wall and liver before reaching systemic circulation
The first-pass effect (pre-systemic metabolism) occurs when an orally absorbed drug passes through the portal circulation to the liver and is partially metabolized before reaching systemic circulation. This significantly reduces bioavailability for some drugs (e.g., morphine, propranolol, nitrates have high first-pass effect — hence why sublingual/IV routes bypass it).
A diabetic patient on metformin 1000mg twice daily presents for medication review. Their latest eGFR is 28 mL/min/1.73m². What action should the pharmacist recommend?
Answer: Stop metformin immediately and recommend the prescriber switch to an alternative
Metformin is contraindicated when eGFR falls below 30 mL/min due to accumulation and increased risk of lactic acidosis. At eGFR 28, metformin should be discontinued. The prescriber should be notified to switch to an alternative antidiabetic agent appropriate for severe renal impairment (e.g., insulin, repaglinide, some DPP-4 inhibitors with dose adjustment).
What is the clinical significance of the 'therapeutic index' of a drug?
Answer: The ratio between the toxic dose and the effective dose; a narrow therapeutic index indicates little safety margin between effective and toxic doses
The therapeutic index (TI) = TD50/ED50 (toxic dose for 50% of subjects / effective dose for 50% of subjects). A narrow TI means the toxic dose is close to the effective dose, requiring careful monitoring. Examples: warfarin, digoxin, lithium, phenytoin, aminoglycosides — all have narrow TI.