Fatal Suicide Attempt with Upadacitinib (Rinvoq®) in an Adolescent: A Case Report

<b>Background and Clinical Significance</b>: Upadacitinib, a selective Janus kinase 1 (JAK1) inhibitor, is increasingly prescribed for autoimmune and inflammatory diseases. Although its therapeutic safety profile is well established, fatal intoxications have not been reported to date. <b>Case Presentation</b>: We describe the first fatal case of upadacitinib overdose in a 13-year-old girl. Following ingestion of approximately 600 mg (40 × 15 mg tablets Rinvoq^®), the patient presented with deep coma, profound bradycardia (~40 bpm) with third-degree atrioventricular block, conduction delay, hypotension, hypothermia, and metabolic acidosis. Laboratory tests showed hyperglycemia (17.8 mmol/L) and only minimal elevations in cardiac biomarkers (CK 57.03 U/L, CK-MB 30.64 U/L, troponin 0.003 ng/mL). Despite advanced resuscitation, the patient succumbed within a few hours. Forensic toxicology revealed extremely high concentrations of upadacitinib, 1.84 µg/mL (~1840 ng/mL) in blood and 70.3 µg/mL in gastric contents, far exceeding reported therapeutic plasma levels (Cmax 36.0 ± 8.8 ng/mL). This case establishes the first reported value for a lethal upadacitinib concentration in humans. The combination of conduction abnormalities, refractory shock, and minimal biomarker changes is consistent with an acute electrophysiological and hemodynamic collapse rather than myocardial infarction. <b>Conclusions</b>: The toxicity of upadacitinib in this case is characterized by profound central nervous system depression, severe cardiovascular (electrophysiological and hemodynamic) disturbances, and metabolic abnormalities (acidosis and hyperglycemia). These findings provide essential reference data for clinical and forensic toxicology, highlight the fatal potential of upadacitinib in overdose, and underscore the importance of secure medication storage and pharmacovigilance in households with adolescents.