FIGURE 1.

Toxicological screening results documenting plasma exposure to phenobarbitone, aminopyrine, and phenacetin. The patient’s plasma sample was collected on 10 March 2026, received by the laboratory on 12 March 2026, and reported on 13 March 2026. Toxicological testing was performed using liquid chromatography–tandem mass spectrometry as part of a 252-compound unknown-poison screening panel. The analysis detected phenobarbital/phenobarbitone (19.50 μg/mL), aminopyrine (32.60 μg/mL), and phenacetin (46.90 μg/mL), all above the laboratory reporting/reference limits. Aminopyrine and phenacetin are known oxidant-related agents capable of contributing to methemoglobin formation. These findings document exposure to components of compound aminopyrine-phenacetin tablets and should be interpreted together with the medication history, MetHb level, oxygen saturation gap, and treatment response.