Which antiviral agent should be avoided in patients with renal impairment?

Acyclovir is an antiviral medication primarily used to treat infections caused by certain types of viruses, particularly herpes simplex virus and varicella-zoster virus. It is primarily eliminated by the kidneys, and its clearance is significantly affected by renal function. In patients with renal impairment, the decreased ability to clear acyclovir from the body can lead to accumulation of the drug, resulting in a higher risk of toxicity, which includes neurological side effects like confusion and seizures. Therefore, acyclovir should be used cautiously and with dose adjustments in patients with renal impairment, or avoided altogether if the impairment is severe.

In contrast, the other antiviral agents listed have different elimination pathways or dosages that may not be as critically impacted by renal function to the same extent as acyclovir. For example, ribavirin should also be used cautiously in patients with renal impairment but is not as strictly contraindicated; oseltamivir has a dosage adjustment for renal impairment but remains usable; and sofosbuvir is primarily metabolized in the liver and less affected by renal function. Understanding the pharmacokinetics of these drugs highlights the necessity of considering renal function in antiviral therapy.