Reversible Mental Status Change and Renal Dysfunction Associated With the Use of High-Dose Oral Valaciclovir Therapy for Acute Retinal Necrosis

In Brief Purpose: The purpose of this study was to report the case of a patient with acute retinal necrosis who developed neurotoxicity while being treated with oral valaciclovir antiviral therapy. Methods: Testing used was clinical examination including fundus photographs, renal biochemistry, cerebrospinal fluid analysis, and renal ultrasound. Results: A 63-year-old, healthy, white woman was being treated with oral valaciclovir for acute retinal necrosis. Several days later, she developed visual hallucinations and confusion. Renal biochemistry was abnormal, and renal ultrasound was normal. Cerebrospinal fluid cellularity was normal, but cerebrospinal fluid 9-carboxymethoxymethylguanine, an aciclovir metabolite, level was elevated. Treatment was changed to intravenous aciclovir titrated based on serum aciclovir levels with intravenous fluid supplementation to good effect. Conclusion: Regular monitoring of renal function and ample fluid intake are important when high doses of aciclovir/valaciclovir are used, even in patients with no previous history of renal failure. Monitoring of serum aciclovir level is useful in those with renal impairment to titrate doses, and high-dose oral valaciclovir should be used with caution. We report a case of valaciclovir neurotoxicity in the treatment of acute retinal necrosis. It is important to recognize early signs of treatment side effects more commonly associated with intravenous antiviral therapy, and high-dose oral valaciclovir should be used with caution.