Suitability of Hair Testing in Medical Dispensing Errors: A Fatal Case of Gliclazide Poisoning

A patient was prescribed a new treatment, 40 mg furosemide. Her pharmacist mistakenly dispensed 40 mg gliclazide instead. After 3 weeks of treatment, the patient was found in a coma, was hospitalised and died after a week. Hair sample was collected during post-mortem examination and tested for gliclazide on three 2 cm sections, starting at the root end. Hair strands were decontaminated, segmented and incubated in the presence of diazepam-d₅, and a solid-liquid extraction has been performed. Finally, toxicological analyses were performed by UFLC Shimadzu Prominence - MS/MS Sciex 6500 QTRAP. Gliclazide was found on the proximal (238 pg/mg), median (77 pg/mg) and distal (69 pg/mg) segments. The concentration in the proximal segment was largely higher than in the other two, which demonstrates repeated intake of gliclazide by the patient during at least the last 2 months before death. The lower concentrations in the medial and distal segments, as well as a part of the concentration in the proximal segment, may be linked to external hair contamination. These could be due to either radial sweat diffusion, possibly occurring in the last week hospitalisation of the patient, or to biological fluids contamination during post-mortem examination. This case illustrates the opportunity to confirm slow and fatal chronic poisoning by gliclazide using hair analysis and shows the benefit of hair testing for the investigation of medical or dispensing errors.