Time-dependent changes in serum concentrations of acyclovir and its metabolite, 9-carboxymethoxymethylguanine, in a patient with suspected acyclovir encephalopathy

• Abe Kazumasa

  Department of Hospital Pharmaceutics, Showa University School of Pharmacy

• Kaizaki-Mitsumoto Asuka

  Division of Toxicology, Department of Pharmacology, Toxicology and Therapeutics, Showa University School of Pharmacy Showa University Pharmacological Research Center

• Saito Tomohiro

  Division of Nephrology, Department of Medicine, Showa University School of Medicine

• Sugiyama Motonori

  Division of Nephrology, Department of Medicine, Showa University School of Medicine

• Honda Hirokazu

  Division of Nephrology, Department of Medicine, Showa University School of Medicine

• Numazawa Satoshi

  Division of Toxicology, Department of Pharmacology, Toxicology and Therapeutics, Showa University School of Pharmacy Showa University Pharmacological Research Center

Abstract

Valacyclovir, a prodrug of acyclovir, may cause adverse drug reactions, so called acyclovir encephalopathy. The acyclovir encephalopathy may not be explained simply by acyclovir blood concentrations, because recent reports suggest the involvement of 9-carboxymethoxymethylguanine (CMMG), a major metabolite of acyclovir. The present study demonstrates changes in serum concentrations of acyclovir and CMMG in a patient with suspected acyclovir encephalopathy. A 63-year-old male was prescribed loxoprofen and valacyclovir for herpes zoster. Seven days after the start of medication, he showed signs of confusion. The next morning, he was emergently transported to hospital for a suspected stroke. There was no stroke lesion but evidence of acute kidney injury, so the patient was given emergency dialysis. With daily hemodialysis sessions performed for three days, the serum concentrations of acyclovir and CMMG decreased, and his state of consciousness improved accordingly.The metabolite CMMG, as well as acyclovir, is efficiently removed by hemodialysis and symptoms of acyclovir encephalopathy improved with decreased serum concentrations. Therefore, if other organic diseases can be ruled out in a patient with suspected acyclovir encephalopathy, it is advisable to introduce hemodialysis immediately.

Journal

• Fundamental Toxicological Sciences

  Fundamental Toxicological Sciences 8 (7), 229-233, 2021

  The Japanese Society of Toxicology

Keywords

• Valacyclovir
• Acyclovir
• 9-Carboxymethoxymethylguanine
• Encephalopathy
• Hemodialysis

Details

• CRID: 1390571968052654848
• NII Article ID: 130008132071
• DOI: 10.2131/fts.8.229
• ISSN: 2189115X
• Web Site: https://www.jstage.jst.go.jp/article/fts/8/7/8_229/_pdf
• Web Site: https://search.jamas.or.jp/link/ui/2023054763
• Text Lang: en
• Data Source:
  • JaLC
  • Crossref
  • CiNii Articles
  • KAKEN
• Abstract License Flag: Disallowed