Epidemiology, toxicokinetics and biomarkers after self-poisoning with Gloriosa superba

Introduction: Gloriosa superba is a flowering plant that contains colchicine. Deliberate self-poisoning with this plant in Sri Lanka is common and potentially fatal. The objective of this study was to describe the epidemiology, toxicokinetics and selected biomarkers in these patients. Materials and methods: The study consisted of three parts; epidemiologic and outcome data (n = 297), concentrations and toxicokinetics (n = 72), evaluation of urinary and serum biomarkers (n = 45). Plasma colchicine levels were measured by high-performance liquid chromatography (HPLC). We also measured serum biomarkers: creatinine (sCr), cystatin C (sCysC) and creatine kinase (CK), and urinary biomarkers: creatinine, kidney injury molecule-1 (KIM - 1), clusterin, albumin, beta-2-microglobulin (β2M), cystatin C, neutrophil gelatinase-associated lipocalin (NGAL), osteopontin (OPN) and trefoil factor 3 (TFF3). Results: The case fatality was 10% (29/297), and death was much more common in older patients. Median concentrations of colchicine were higher in those over 65 [median 4.7 ng/mL (IQR: 1.7-6.6) vs. 1.2 (IQR: 0.2-2.7) for those <35]. Admission colchicine concentrations were highly correlated with a fatal outcome [median 7.8 ng/ml (IQR: 5.8-18.7) vs 1.2 (0-2.3) in survivors]. The area under the receiver operating characteristic curve (AUC-ROC) for uncorrected admission colchicine level was highly predictive of a fatal outcome, and this improved even further with two methods we developed to correct for the expected change with time. The best method had an AUC-ROC of 0.98 (95%CI 0.94-1.00) in predicting death, with 100% sensitivity and 96% specificity at the best cut-point. Discussion: Fatal outcomes and high concentrations were both much more common in the elderly following poisoning with Gloriosa superba. Our findings are consistent with kinetic data after medicinal colchicine ingestion. Conclusions: Gloriosa superba self-poisoning causes significant mortality. High concentration of colchicine is highly predictive of a fatal outcome. Ingestion of Gloriosa superba caused only mild acute kidney injury (AKI) and rhabdomyolysis.