Faculty Bibliography

BACKGROUND:Although chloroquine, hydroxychloroquine, and quinine are used for a range of medical conditions, recent research suggested a potential role in treating COVID-19. The resultant increase in prescribing was accompanied by an increase in adverse events, including severe toxicity and death. The Extracorporeal Treatments in Poisoning (EXTRIP) workgroup sought to determine the effect of and indications for extracorporeal treatments in cases of poisoning with these drugs. METHODS:We conducted systematic reviews of the literature, screened studies, extracted data, and summarized findings following published EXTRIP methods. RESULTS:studies, two animal studies, 28 patient reports or patient series, and 11 pharmacokinetic studies) met inclusion criteria regarding the effect of extracorporeal treatments. Toxicokinetic or pharmacokinetic analysis was available for 61 patients (13 chloroquine, three hydroxychloroquine, and 45 quinine). Clinical data were available for analysis from 38 patients, including 12 with chloroquine toxicity, one with hydroxychloroquine toxicity, and 25 with quinine toxicity. All three drugs were classified as non-dialyzable (not amenable to clinically significant removal by extracorporeal treatments). The available data do not support using extracorporeal treatments in addition to standard care for patients severely poisoned with either chloroquine or quinine (strong recommendation, very low quality of evidence). Although hydroxychloroquine was assessed as being non-dialyzable, the clinical evidence was not sufficient to support a formal recommendation regarding the use of extracorporeal treatments for this drug. CONCLUSIONS:On the basis of our systematic review and analysis, the EXTRIP workgroup recommends against using extracorporeal methods to enhance elimination of these drugs in patients with severe chloroquine or quinine poisoning.

Objective: Hyperthermia is a life-threatening complication of agitated delirium, and a potential consequence of sympathomimetic, anticholinergic, or oxidative phosphorylation uncoupling xenobiotics. Failure to promptly cool a hyperthermic patient leads to morbid sequelae, including rhabdomyolysis, acute kidney injury, ischemic hepatitis (shock liver), disseminated intravascular coagulation, and possibly death. The primary objective of this study is to assess one Poison Control Center's (PCC) experience with hyperthermic patients, specifically as it relates to the use of ice or water bath treatment. Secondary objectives include characterizing mortality rate, ambient temperatures at the time of presentation, and initial laboratory abnormalities.
Method(s): This is a retrospective analysis of data from a single PCC from 2014 to 2019. A structured query language search (SQL) of Toxicall

Objective: We present a patient who developed prolonged coma following treatment of ethanol withdrawal with large doses of diazepam and demonstrated prolonged elimination toxicokinetics. Case report: A 68-year-old man who drank 5-6 alcoholic beverages/day was admitted for an elective transcatheter aortic valve replacement. Two days post-procedure, he developed agitation and was presumptively treated for ethanol withdrawal with diazepam (470 mg IV over 24 hours). He remained comatose for four days prompting a toxicology consult. On day 7 of persistent coma from presumed benzodiazepine excess, flumazenil (0.5 mg) was administered; he opened his eyes for the first time, began speaking, and answering simple questions, but 30 minutes later was comatose again. Flumazenil infusion 0.25mg/h was trialed with unclear effect. His hospitalization was complicated by gastrointestinal bleeding and mild ischemic stroke deemed noncontributory to his clinical status. The flumazenil infusion was discontinued 1 week later. His evaluation was extensive (brain magnetic resonance imaging and computerised tomography, lumbar puncture, and blood cultures) and unremarkable. On hospital week 4, he became only gradually more awake, and was eventually discharged to a rehabilitation facility on hospital week 6, awake, conversive but still confused. Six weeks later, he was discharged home fully recovered. He remains amnestic to his hospitalization. Serum diazepam and nordiazepam concentrations were determined via liquid-chromatography mass-spectrometry. Concentrations obtained four days after the last dose were: diazepam 963 mug/L (therapeutic: 200-1000 mug/L) and nordiazepam 240 mug/L (therapeutic: 100-1500 mug/L). Elimination kinetics were calculated with apparent half-lives of 294 hours and 797 hours for diazepam and nordiazepam, respectively. Genotyping of CYP3A4 and CYP2C19, the two primary metabolizers of diazepam, demonstrated no abnormalities.
Conclusion(s): Diazepam demonstrated extremely atypical elimination kinetics despite normal renal and hepatic function. Acute tolerance which is expected after prolonged benzodiazepine exposure was not clearly demonstrated. The relationship between his serum concentration and clinical status is unclear at this time

INTRODUCTION/BACKGROUND:Severe baclofen toxicity can result in respiratory failure, hemodynamic instability, bradycardia, hypothermia, seizures, coma, and death. While hemodialysis (HD) is well-described in treating acute baclofen toxicity in patients with end-stage kidney disease or acute kidney injury, the utility of HD for patients with normal kidney function is uncertain. Implementing HD to speed recovery after a large acute baclofen ingestion is appealing, considering: (a) potential for prolonged coma and ventilator-associated morbidity, and (b) baclofen's low protein-binding, low molecular-weight, and moderate volume of distribution. METHODS:We report a 51 kg, 14-year-old girl who presented to the emergency department (ED) with hypotension, obtundation, and status epilepticus after an intentional ingestion of 1200 mg baclofen. Her post-intubation neurologic examination was concerning for coma. A 14-hour post-ingestion baclofen concentration was 882 ng/mL (therapeutic range 80-400 ng/mL). Three urgent-HD sessions were performed to reduce her time on the ventilator. RESULTS:The total baclofen removed in the first three-hour HD session was 3.05 mg. The total urinary elimination of baclofen 42 mg over 24-hours on day one. She was discharged without neurologic deficits to psychiatry on day-14. CONCLUSION/CONCLUSIONS:In this case, the amount of baclofen recovered during HD is negligible in comparison to the amount cleared by kidney elimination in this patient with normal kidney function.

Hemodialysis (HD) has limited efficacy towards treatment of drug toxicity due to strong drug-protein binding. In this work, we propose to infuse a competitor drug into the extracorporeal circuit that increases the free fraction of a toxic drug and thereby increases its dialytic removal. We used a mechanistic model to assess the removal of phenytoin and carbamazepine during HD with or without binding-competition. We simulated dialytic removal of (1) phenytoin, initial concentration 70 mg/L, using 2000 mg aspirin, (2) carbamazepine, initial concentration 35 mg/L, using 800 mg ibuprofen, in a 70 kg patient. The competitor drug was infused at constant rate. For phenytoin (~ 13% free at t = 0), HD brings the patient to therapeutic concentration in 460 min while aspirin infusion reduces that time to 330 min. For carbamazepine (~ 27% free at t = 0), the ibuprofen infusion reduces the HD time to reach therapeutic concentration from 265 to 220 min. Competitor drugs with longer half-life further reduce the HD time. Binding-competition during HD is a potential treatment for drug toxicities for which current recommendations exclude HD due to strong drug-protein binding. We show clinically meaningful reductions in the treatment time necessary to achieve non-toxic concentrations in patients poisoned with these two prescription drugs.