Toxicokinetics of thebaine in those consuming non-food grade poppy seeds as a tea.

Introduction: Thebaine is an alkaloid in poppy seeds that is neurotoxic to animals. Data on its clinical effects and toxicokinetics in people are minimal. In 2022, poppy seeds high in thebaine entered the Australian food market, and people consuming tea made from these poppy seeds developed poisoning.

Methods: Three patients who drank poppy seed tea and developed neuromuscular toxicity consented for thebaine to be quantitated in serial blood samples. Blood samples were analyzed by liquid chromatography with high-resolution mass spectrometry.

Results: A man in his 60s presented with drowsiness, vomiting, malaise and myoclonus. He developed metabolic acidosis with hyperlactataemia, acute kidney injury requiring haemodialysis, convulsions, rhabdomyolysis, and was in the hospital for 18 days. The admission thebaine blood concentration was 2.1 mg/L, and the apparent elimination half-life was 14.8 h. A man in his 30s presented with myoclonus, rigidity, vomiting, and dizziness. He developed metabolic acidosis with hyperlactataemia, acute kidney injury, and myalgias. The admission thebaine blood concentration was 4.1 mg/L, and the apparent elimination half-life was 11.6 h. A man in his 30s presented with myoclonus, rigidity, clonus, diaphoresis, and abdominal pain. The admission thebaine blood concentration was 2.2 mg/L, and the apparent elimination half-life was 8.3 h.

Discussion: Neuromuscular toxicity, metabolic acidosis with hyperlactataemia, acute kidney injury, and gastrointestinal symptoms were prominent clinical features in these patients after drinking poppy seed tea. Effects persisted for days, and all survived, despite thebaine concentrations far exceeding those in published forensic reports, although human data are sparse. Compared to rats, the thebaine apparent elimination half-life is much longer in humans who develop symptoms at lower concentrations.

Conclusions: Despite relatively high thebaine blood concentrations and moderate to severe poisoning, outcomes were favourable with early presentations. It is possible that acute kidney injury prolongs the apparent elimination half-life of thebaine.