Editing Reduction of Risk Potential (section)

=== Therapeutic Drug Levels ===

;Digoxin, approximately 0.5 to 2.0 ng/mL, with many heart failure regimens targeting the lower end
Toxicity presents with anorexia, nausea and vomiting, visual disturbance including yellow-green halos, bradycardia, and dysrhythmias. Hypokalemia, hypomagnesemia, hypercalcemia, renal impairment, and advanced age all increase toxicity risk at a given serum level. Nursing application: count the apical pulse for a full minute and hold the dose for an adult rate below 60 beats per minute, following facility policy, then report (Ignatavicius et al., 2021; Pagana et al., 2022).

;Lithium, approximately 0.6 to 1.2 mEq/L maintenance; toxicity risk rises above about 1.5 mEq/L
Sodium and fluid loss from dehydration, vomiting, diarrhea, sweating, low sodium diets, and thiazide diuretics and nonsteroidal anti-inflammatory drugs raises lithium levels. Early toxicity brings nausea, diarrhea, fine tremor, and drowsiness; severe toxicity brings coarse tremor, ataxia, confusion, and seizures (Pagana et al., 2022).

;Phenytoin, approximately 10 to 20 mcg/mL
Toxicity presents with nystagmus, ataxia, slurred speech, and confusion. Gingival hyperplasia is a chronic effect requiring meticulous oral care. Intravenous phenytoin is compatible with normal saline, not dextrose, and is infused slowly because of hypotension and dysrhythmia risk (Pagana et al., 2022).

;Theophylline, approximately 10 to 20 mcg/mL
Toxicity presents with tachycardia, restlessness, nausea, and seizures (Pagana et al., 2022).

;Vancomycin trough, commonly 10 to 20 mcg/mL depending on indication
Draw the trough immediately before the next dose. Monitor renal function and hearing. Rapid infusion causes flushing of the face and upper body from histamine release, which is an infusion-rate reaction rather than a true allergy, and is managed by slowing the infusion (Harding et al., 2023; Pagana et al., 2022).

;Aminoglycosides such as gentamicin
Nephrotoxic and ototoxic. Peak and trough monitoring plus creatinine surveillance is standard; report new tinnitus, vertigo, or hearing change (Pagana et al., 2022).