A 70-year-old 45-kg patient is admitted to the ICU with a diagnosis of digoxin intoxication. The patient complains of nausea, blurred vision, and fatigue that have been present for 3 days. A cardiac monitor reveals a HR of 42 bpm, an irregular rhythm, and a type second-degree heart block. Current medications include digoxin 0.25 mg and furosemide 40mg for heart failure, both taken daily at 0800. The patient remains adherent to all medications despite nausea, including today's doses. Blood is drawn at 1200 with the following results:
* Potassium: 6.0 mEq/L
* Creatinine: 2.3 mg/dL
* Digoxin: 1.7 ng/mL
Which of the following most appropriately describes the patient's digoxin concentration?