Rapidly progressive acute renal failure due to acyclovir: case report and review of the literature.

Acyclovir nephrotoxicity has been described since the inception of the drug's use more than a decade ago. Acute renal failure mediated by this compound is characterized by abrupt elevations in serum creatinine and a gradual return to baseline renal function on discontinuation of the drug. Drug crystal formation in collecting tubules resulting in an intraparenchymal form of obstructive nephropathy has been suggested as the mechanism for acyclovir nephrotoxicity. The patient we present developed rapidly progressive acute renal failure with concomitant mental status changes in the setting of treatment with high-dose parenteral acyclovir. Acyclovir therapy was discontinued and an open renal biopsy was obtained to further evaluate our patient's diminishing renal function. Pathologic examination of the biopsy specimen revealed loss of proximal tubule brush border and dilated proximal and distal tubules with flattening of lining cells and focal nuclear loss. No crystals were noted. These changes were consistent with acute tubular necrosis with regeneration. Over the next 4 days our patient's renal and neurologic levels recovered to their prehospitalization statuses. It appears that our patient was affected by acyclovir-mediated nephrotoxicity that manifested on biopsy by acute tubular necrosis and the absence of crystalluria or crystal deposition. Intravenous acyclovir treatment can therefore produce rapidly progressive acute neurologic and renal toxicity that is usually reversible. The pathologic changes of acute tubular necrosis must now be included as part of the spectrum of renal damage associated with acyclovir therapy.