A 42-year-old woman with cystic fibrosis is admitted with acute exacerbation of Pseudomonas aeruginosa lung infection. She is prescribed tobramycin 7 mg/kg IV once daily for 14 days. Her baseline renal function is normal (serum creatinine 0.8 mg/dL, eGFR 95 mL/min/1.73m²). On day 10, she develops vertigo, nausea, and nystagmus. Audiometry shows high-frequency sensorineural hearing loss. Which of the following best describes the pharmacokinetic property of aminoglycosides that predisposes to this adverse effect, and what is the most appropriate management?