Which side effect should a healthcare professional monitor for in a patient receiving acyclovir?

When a patient is receiving acyclovir, monitoring for nephrotoxicity is crucial. Acyclovir is primarily excreted by the kidneys, and in certain circumstances—especially in cases of rapid infusion or dehydration—the drug can precipitate in the renal tubules, leading to acute kidney injury or impairment of renal function. This is due to the formation of crystals in the renal tubules, which can obstruct urine flow and damage renal tissue.

Patients at higher risk include those with pre-existing renal impairment, dehydration, or those receiving high doses of acyclovir. Monitoring renal function through serum creatinine levels and urine output is essential during acyclovir therapy to identify any signs of nephrotoxicity early and to take appropriate measures to prevent further complications.

Other potential side effects of acyclovir, such as respiratory depression, hepatic failure, or cardiac arrest, are not as closely associated with its mechanism of action and pharmacokinetics, making nephrotoxicity the primary concern to be monitored in patients receiving this antiviral treatment.