Vol.74 No.3 May 2026

Acetaminophen-induced liver injury in a patient with necrotizing soft tissue infection diagnosed by rapid in-house high-performance liquid chromatography

Yohei Manabe^{1, 2)}, Hidemasa Akazawa^{2, 3)}, Shinnosuke Fukushima^{2, 3)}, Kenta Nakamoto^{2, 3)}, Kohei Oguni^{2, 3)} and Hideharu Hagiya^{2, 3)}

¹⁾Department of Pharmacy, Okayama University Hospital, 2-5-1 Shikata, Kita-ku, Okayama, Japan
²⁾Division of Infection Prevention and Control, Okayama University Hospital
³⁾Department of Infectious Diseases, Okayama University Hospital

Abstract

A 73-year-old woman (body weight, 44 kg) with no significant past medical history presented to us with necrotizing soft tissue infection of the groin and was treated by debridement and antimicrobial therapy. Intravenous acetaminophen (AAP) at 4,000 mg/day was initiated on day 2 for pain control. From day 4, she showed rapid elevation of the serum liver enzyme levels. Imaging revealed no structural liver or biliary tract abnormalities, and serological testing excluded acute viral and autoimmune hepatitis. As her hemodynamic status remained stable, ischemic liver injury was considered unlikely, and AAP-induced liver injury was strongly suspected. On day 7, the serum AAP concentration was assessed by in-house high-performance liquid chromatography (HPLC: Hitachi High-Tech Analysis Corporation, Tokyo, Japan). Analysis of a blood specimen collected on day 4, approximately four hours post-AAP administration, showed a concentration of 50.53 μg/mL, markedly exceeding the reported reference range for healthy individuals (5-10 μg/mL), confirming the suspicion of AAP-induced liver injury. Typically, measurement of serum AAP levels relies on outsourced laboratories, with results taking several days to return. In this case, however, in-house HPLC enabled immediate determination, contributing to both rapid diagnosis and prompt modification of the pain management strategy. Following discontinuation of AAP, the serum liver enzyme levels began to improve, returning to their normal ranges by day 25. This case highlights the potential usefulness of rapid in-house HPLC measurement in facilitating timely diagnosis and prompt treatment initiation in patients with suspected drug-induced liver injury.

Key word

acetaminophen, hepatotoxicity, therapeutic drug monitoring, high-performance liquid chromatography, antimicrobial stewardship

Received

September 22, 2025

Accepted

December 22, 2025

Jpn. J. Chemother. 74 (3): 438-443, 2026