A patient with chronic congestive heart failure has repeated hospitalizations despite ongoing treatment with hydrochlorothiazide (HydroDIURIL) and digoxin. The prescriber has ordered spironolactone (Aldactone) to be added to this patient’s drug regimen, and the nurse provides education about this medication. Which statement by the patient indicates understanding of the teaching?

Choice A reason: Drugs with a narrow therapeutic range, like digoxin, require plasma level monitoring to ensure concentrations remain within a safe and effective range. This prevents toxicity (e.g., arrhythmias) or subtherapeutic effects, as small dose changes can significantly alter blood levels, making monitoring critical for patient safety and efficacy.

Choice B reason: Intravenous administration does not inherently address the risks of a narrow therapeutic range. While it ensures rapid delivery, it increases toxicity risk due to immediate bioavailability. Monitoring plasma levels is more critical than the route to maintain safe and effective drug concentrations, making this choice less appropriate.

Choice C reason: Administering at intervals longer than the half-life may lead to subtherapeutic levels for drugs with a narrow therapeutic range, reducing efficacy. Consistent dosing and plasma level monitoring are needed to maintain steady-state concentrations within the therapeutic window, making this choice incorrect for managing such drugs.

Choice D reason: Teaching that maximum effects occur quickly is inaccurate for most narrow therapeutic range drugs, which often require steady-state concentrations over time. Without monitoring, toxicity or inefficacy risks increase. Patient education should focus on adherence and monitoring, not rapid effects, making this choice inappropriate.

Choice A reason: Affinity is not about dosage form but the strength of drug-receptor binding. Dosage is unrelated to receptor interaction, so this is incorrect for affinity’s definition.

Choice B reason: Low affinity means weak attraction to receptors, not strong. High affinity indicates strong binding, so this statement is incorrect.

Choice C reason: High affinity means strong attraction between drug and receptor, enhancing binding and effect. This is accurate, making it a correct choice.

Choice D reason: Affinity influences potency; higher affinity often means greater potency at lower doses. This relationship is correct, making it a correct choice.

Choice E reason: Affinity is the strength of attraction between drug and receptor, a fundamental pharmacological concept. This definition is accurate, so this is a correct choice.