What serious side effect is associated with high doses of acyclovir?

Acyclovir is an antiviral medication primarily used to treat infections caused by certain types of viruses, particularly herpes simplex virus and varicella-zoster virus. One significant concern with acyclovir is its potential to cause nephrotoxicity, particularly when administered at high doses or given rapidly via intravenous (IV) infusion.

The mechanism behind this nephrotoxicity is primarily due to the crystallization of acyclovir in the renal tubules. When the drug is concentrated in the kidneys, especially in the presence of dehydration or rapid infusion, it can lead to obstruction within the renal tubules, causing acute kidney injury. This is why hydration is often recommended during acyclovir administration to help reduce the risk of renal complications.

In contrast, while acyclovir can have various side effects, the other options listed—hepatotoxicity, pulmonary toxicity, and ototoxicity—are not typically associated with this medication, particularly in a dose-dependent manner. Understanding the specific side effects of antiviral medications like acyclovir is crucial for effectively managing patient care and minimizing risks.