thebaine and Seizures

Poppy seed tea is used for its opioid effects and contains multiple opium alkaloids, including morphine, codeine, papaverine, and thebaine. Animal studies indicate thebaine has strychnine-like properties, but there is limited literature describing human thebaine poisoning. We describe a cluster of acute thebaine poisoning in people ingesting tea made using poppy seeds with high thebaine content that entered the Australian food supply chain.. This is an observational study of patients poisoned after drinking poppy seed tea. Cases were identified by three prospective toxicovigilance systems: the Emerging Drug Network of Australia collaboration, the New South Wales Prescription, Recreational and Illicit Substance Evaluation program, and the Emerging Drugs Network of Australia Victoria study. We report characteristics of clinical toxicity in cases with reported ingestion of poppy seed tea and analytical confirmation of thebaine exposure.. Forty cases presenting with multi-system toxicity following poppy seed tea ingestion were identified across seven Australian states/territories from November 2022 to January 2023. Blood testing in 23 cases confirmed high thebaine concentrations. All 23 were male (median age 35, range 16-71 years). All patients experienced muscle spasms. Rigidity was described in nine, convulsions in six, while rhabdomyolysis, acute kidney injury, and metabolic acidosis occurred in five patients. There were two cardiac arrests. The thebaine median admission blood concentration was 1.6 mg/L, with a range of 0.1-5.6 mg/L, and was the dominant opium alkaloid in all samples. Convulsions, acute kidney injury, metabolic acidosis, and cardiac arrest were associated with increasing median thebaine concentrations. Four patients were managed in the Intensive Care Unit, with two receiving continuous kidney replacement therapy (one also received intermittent haemodialysis) for kidney injury. There was one death.. Thebaine toxicity, like strychnine poisoning, resulted in neuromuscular excitation characterized by muscle spasm, rigidity, and convulsions. Severe toxicity, including acute kidney injury, metabolic acidosis, and cardiac arrest, appears dose-dependent.

Topics: Acidosis; Acute Kidney Injury; Adolescent; Adult; Aged; Animals; Codeine; Female; Heart Arrest; Humans; Male; Middle Aged; Morphine; Opium; Papaver; Prospective Studies; Seeds; Seizures; Strychnine; Tea; Thebaine; Victoria; Young Adult

The influence of centrally administered meperidine, normeperidine and pentazocine on the excitability of brain was studied by measuring the threshold for flurothyl-induced convulsions in rats. All three opioids are reported to lower seizure thresholds when given subcutaneously to rats in this test. Dose-and time-dependent changes in the seizure threshold occurred after intracerebroventricular injection of pentazocine (10-160 micrograms), meperidine (25-150 micrograms) and normeperidine (50-150 micrograms). Rapid increases in the seizure threshold were associated with pentazocine and meperidine, whereas a slowly developing decrease in the threshold was caused by normeperidine. Naloxone (10 mg/kg, s.c.) antagonized the anticonvulsant effect of meperidine (but not that of pentazocine) and enhanced the proconvulsant effect of normeperidine. Thebaine (25-150 micrograms), which had no marked influence on the seizure threshold when given intracerebroventricularly, lowered the threshold after subcutaneous injection of 12.5 and 25 mg/kg. This effect was not altered by injection of naloxone. These results show that centrally administered opioids can act on excitatory or inhibitory systems that regulate seizure mechanisms in the rat brain. Furthermore both naloxone-sensitive and naloxone-insensitive components are involved. Meperidine, pentazocine and thebaine have different actions on the seizure threshold after intracerebroventricular, as opposed to subcutaneous, administration. This work has, therefore, identified the route of administration as a critical variable in the effect of opioids on the seizure threshold in rats.

Topics: Animals; Brain; Dose-Response Relationship, Drug; Flurothyl; Injections, Intraventricular; Male; Meperidine; Naloxone; Narcotics; Pentazocine; Rats; Rats, Inbred Strains; Seizures; Thebaine

Naloxone antagonized convulsions produced by tail vein infusions of d-propoxyphene, heroin, meperidine, normeperidine and thebaine in mice in a dose-related manner. Pretreatment with naloxone (60 mg/kg i.p.) produced a 200 percent increase of the dose of d-propoxyphene or heroin needed to produce a seizure. A 40 percent increase in the convulsant dose of meperidine was observed after naloxone pretreatment (30 mg/kg i.p.). Naloxone (15 mg/kg i.p.) produced a 30 percent increase in the convulsant dose of normeperidine; however, larger doses of naloxone did not produce any further increase in the convulsant dose of either normeperidine or meperidine. Larger doses of naloxone were needed to antagonize convulsions produced by thebaine. Heroin, d-propoxyphene and meperidine produced nonlethal clonic seizures, whereas normeperidine and thebaine produced tonic-clonic seizures which were followed by death. These data suggest that there may be two mechanisms by which narcotic analgesics and their congeners produce convulsions.

Topics: Animals; Anticonvulsants; Dextropropoxyphene; Heroin; Male; Meperidine; Mice; Naloxone; Nipecotic Acids; Seizures; Thebaine

Topics: Animals; Behavior, Animal; Cats; Cerebral Cortex; Depression, Chemical; Electrodes, Implanted; Electroencephalography; Electrophysiology; Female; Injections, Intraperitoneal; Injections, Intravenous; Injections, Subcutaneous; Lethal Dose 50; Male; Mice; Mice, Inbred Strains; Morphinans; Morphine; Rabbits; Respiration; Seizures; Stimulation, Chemical; Thebaine

Topics: Animals; Electric Stimulation; Electroshock; Male; Morphine; Oxygen Consumption; Pentylenetetrazole; Plethysmography; Rats; Respiration; Seizures; Stress, Physiological; Thebaine

Topics: Animals; Body Temperature; Central Nervous System; Environmental Exposure; Male; Mice; Pentylenetetrazole; Seizures; Stress, Physiological; Strychnine; Temperature; Thebaine