Medication Management Flashcards

A patient's INR is 3.8 (therapeutic range 2.0–3.0 for atrial fibrillation). They have no active bleeding. What is the nurse's action?

Answer: Hold the next warfarin dose and notify the physician for dose adjustment

An INR of 3.8 is above the therapeutic range for atrial fibrillation (2.0–3.0), increasing bleeding risk. The next dose should be held and the prescriber notified for dose adjustment. The INR will be rechecked after the hold. IV vitamin K is reserved for INR >10 or active bleeding.

A patient prescribed furosemide (loop diuretic) should be monitored for which electrolyte imbalance?

Answer: Hypokalemia and hypomagnesemia

Loop diuretics inhibit the Na-K-2Cl cotransporter in the loop of Henle, causing loss of sodium, potassium, magnesium, and chloride. Hypokalemia and hypomagnesemia are common adverse effects requiring supplementation monitoring, especially significant in patients on digoxin.

An adult patient weighing 80 kg requires a dopamine infusion at 5 mcg/kg/min. The solution concentration is 400 mg in 250 mL. What is the infusion rate in mL/hr?

Answer: 15 mL/hr

Step 1: 5 mcg/kg/min × 80 kg = 400 mcg/min. Step 2: 400 mg/250 mL = 1.6 mg/mL = 1,600 mcg/mL. Step 3: 400 mcg/min ÷ 1,600 mcg/mL = 0.25 mL/min. Step 4: 0.25 × 60 = 15 mL/hr.

A patient is taking nifedipine (calcium channel blocker) for hypertension. Which food interaction must be discussed?

Answer: Avoid grapefruit juice — it inhibits CYP3A4 and dramatically increases nifedipine levels

Grapefruit juice inhibits intestinal CYP3A4 enzymes, which normally metabolize nifedipine. This increases plasma nifedipine levels by up to 2–3 times, causing excessive vasodilation, hypotension, reflex tachycardia, and flushing. This interaction applies to all dihydropyridine CCBs.

What is the mechanism of action of aspirin as an antiplatelet agent?

Answer: Irreversible inhibition of COX-1 and COX-2, preventing thromboxane A2 synthesis and platelet aggregation

Aspirin irreversibly acetylates and inhibits cyclooxygenase (COX-1 predominantly), blocking thromboxane A2 synthesis. Thromboxane A2 promotes platelet aggregation and vasoconstriction. Because platelets lack a nucleus and cannot synthesize new COX, the effect lasts the platelet's lifespan (7–10 days).

A nurse must administer an intramuscular injection of 3 mL into the deltoid muscle. What should the nurse do?

Answer: Choose a different site; deltoid maximum volume is 1–2 mL

The deltoid muscle can only safely accommodate 1–2 mL of medication. For volumes of 3 mL or more, the ventrogluteal or vastus lateralis sites must be used, as they have larger muscle mass. Exceeding deltoid capacity causes muscle damage, pain, and impaired absorption.