What are the signs of toxicity to look for in patients receiving therapeutic drug monitoring for aminoglycosides?

Signs of toxicity to monitor in patients receiving aminoglycosides include:

• Nephrotoxicity: Look for rising serum creatinine and reduced urine output, indicating acute kidney injury. Aminoglycosides accumulate in renal proximal tubular cells causing nephrotoxicity, which is often reversible if detected early ¹.
• Ototoxicity: Monitor for symptoms such as tinnitus, hearing loss, vertigo, or imbalance. These signs reflect cochlear and vestibular toxicity, which may be irreversible if not identified promptly ¹.
• Neuromuscular blockade: Although rare, watch for muscle weakness or respiratory depression, especially in patients with underlying neuromuscular disorders or those receiving concurrent neuromuscular blocking agents ¹.
• Laboratory monitoring: Therapeutic drug monitoring (TDM) aims to maintain aminoglycoside serum concentrations within a therapeutic range to avoid toxicity. Elevated trough levels correlate with increased risk of nephro- and ototoxicity (Abdul-Aziz et al., 2022).

Regular clinical assessment combined with TDM is essential to detect early toxicity signs and adjust dosing accordingly to prevent permanent damage ¹; (Abdul-Aziz et al., 2022). In neonates, particular vigilance is required due to immature renal function and increased susceptibility to toxicity (Touw et al., 2009).