Remdesivir Discontinuation Decisions Based on Thresholds of Aminotransferase in an Observational Registry.

BACKGROUND: Remdesivir is an antiviral approved by the US Food and Drug Administration (FDA) for treatment of coronavirus disease 2019 (COVID-19), and aminotransferase elevation is commonly reported. Thresholds to be considered for discontinuation due to alanine aminotransferase (ALT) elevation differ between the FDA and European Medicines Agency (EMA). The primary objective was to describe aminotransferase thresholds being used in real-world practice for discontinuation of remdesivir in patients with COVID-19, and compare them with labeled recommendations. METHODS: This study used a descriptive design based on an ongoing national registry of adverse events, the FDA ACMT COVID-19 ToxIC (FACT) pharmacovigilance project, with 17 participating health systems in the USA. Cases were identified retrospectively for an 18-month period (23 November 2020-18 May 2022). Classification of discontinuation as premature and due to aminotransferases was based on chart documentation by the treating team. RESULTS: Of 1026 cases in the FACT registry, 116 cases were included with supplemental data forms completed for aminotransferase elevation with remdesivir, defined a priori for inclusion as ALT doubling or increasing by ≥ 50 U/L. ALT was elevated prior to remdesivir in 47% and increased above baseline during dosing by a median of 92 U/L [interquartile range (IQR) 51-164, max 8350]. Remdesivir was discontinued early in 37 (31.9%) patients due to elevated aminotransferases. The ALT threshold for premature discontinuation was median 200 U/L (IQR 145-396, range 92-5743). Among patients with premature discontinuation of remdesivir for aminotransferase elevation, only 21.6% met FDA criteria to consider discontinuation, and 40.5% met prior EMA criteria to consider discontinuation. CONCLUSION: In this descriptive study of real-world practice in the USA, clinicians are overall making more conservative treatment decisions than are recommended for consideration in approved drug labeling of discontinuation, with wide variation in the aminotransferase thresholds being used.

Decreased Clinical Toxicity and Two-Phase Elimination Kinetics Observed After Intravenous Iron Sucrose Overdose.

BACKGROUND: Management of oral iron overdoses is well-established, but there is limited literature regarding intravenous iron sucrose overdoses. Indications for administering deferoxamine after oral iron overdoses include clinical signs and symptoms of toxicity, along with a serum iron concentration ≥ 500 µg/dL. Reported signs and symptoms of iron sucrose overdose do not appear to correlate with those of oral iron overdoses. CASE REPORT: We present a case of intravenous iron sucrose overdose in a clinically well-appearing patient with a presenting serum iron concentration that was several times higher than the usual threshold concentration for initiating deferoxamine treatment. A 21-year-old woman presented to the emergency department after an accidental intravenous iron sucrose overdose. The patient received a home infusion of 1000 mg iron sucrose, which was five times the prescribed dose. Her presenting serum iron concentration was 1799 µg/dL, with bicarbonate and anion gap both within normal limits and an unremarkable physical examination. Because she did not have evidence of severe iron toxicity, she was treated supportively and deferoxamine was not administered. Her serum iron concentration decreased below the toxic range over the next 14 h, and she was discharged home the next day. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: This patient was managed successfully with expectant care alone, suggesting that iron sucrose overdose has much lower toxicity than oral iron salt overdose. This discrepancy between measured iron concentrations and clinical presentation may be explained by the elimination kinetics of iron sucrose having separate redistribution and elimination phases.

Rates and types of urine drug screen false negative results compared with confirmatory toxicology testing in major trauma patients.

BACKGROUND: Trauma centers are required to screen patients for alcohol use, and if necessary, intervene and refer to treatment (SBIRT). Similar screening for illicit drug use is recommended but not required. Urine drug screening (UDS) underestimates problematic substance use. This study aimed to estimate the types and rates of UDS false negatives (FN) compared to comprehensive testing by liquid chromatography-mass spectrometry (LC-MS) in trauma patients. METHODS: We performed a prospective cohort study of deidentified urine samples from adult trauma and burn activation patients. Both UDS and LC-MS comprehensive testing of >200 analytes were performed by a reference laboratory on all samples. Iatrogenic medications were excluded from the FN count. Crosstab analyses were conducted for UDS versus LC-MS outcomes to establish FN types and rates. We dichotomized the results by creating an "intentionality" variable (intentional injuries by self/others versus accidental injuries). A series of crosstabs with odds ratios considered intentionality by substance class and demographics. Statistically significant variables by Chi-Square were assessed by logistic regression. RESULTS: Psychoactive FN were detected in 56/100 urine samples analyzed; the most frequent included anticonvulsants (primarily gabapentin, N = 13), opioid agonists (N = 12), antihistamines (primarily diphenhydramine, N = 10), and phenethylamines (primarily bupropion, N = 5). Nonpsychoactive FN were detected in 70/100 samples; the most common were nicotine (N = 33), caffeine (N = 23), acetaminophen (N = 22), and antidepressants (N = 12). Of substance classes included in the UDS and also tested by LC-MS, FN occurred for opiates (3%), amphetamines (5%) and opioids (25%). Polypharmacy was associated with fall injuries in elderly patients. Cocaine (p = 0.015) and cannabinoids (p = 0.002) were significantly associated with intentionality. CONCLUSIONS: Our results indicate that FN for potentially important psychoactive and nonpsychoactive substances are common when toxicologic testing is limited to routine UDS in trauma patients. We recommend expanding SBIRT in this patient population to include misuse of tobacco products, prescription analgesics, and over-the-counter antihistamines.

The serum glycolate concentration: its prognostic value and its correlation to surrogate markers in ethylene glycol exposures.

CONTEXT: Ethylene glycol poisoning manifests as metabolic acidemia, acute kidney injury and death. The diagnosis and treatment depend on history and biochemical tests. Glycolate is a key toxic metabolite that impacts prognosis, but assay results are not widely available in a clinically useful timeframe. We quantitated the impact of serum glycolate concentration for prognostication and evaluated whether more readily available biochemical tests are acceptable surrogates for the glycolate concentration. OBJECTIVES: The objectives of this study are to 1) assess the prognostic value of the initial glycolate concentration on the occurrence of AKI or mortality in patients with ethylene glycol exposure (prognostic study); 2) identify surrogate markers that correlate best with glycolate concentrations (surrogate study). METHODS: A systematic review of the literature was performed using Medline/PubMed, EMBASE, Cochrane library, conference proceedings and reference lists. Human studies reporting measured glycolate concentrations were eligible. Glycolate concentrations were related to categorical clinical outcomes (acute kidney injury, mortality), and correlated with continuous surrogate biochemical measurements (anion gap, base excess, bicarbonate concentration and pH). Receiver operating characteristic curves were constructed to calculate the positive predictive values and the negative predictive values of the threshold glycolate concentrations that predict acute kidney injury and mortality. Further, glycolate concentrations corresponding to 100% negative predictive value for mortality and 95% negative predictive value for acute kidney injury were determined. RESULTS: Of 1,531 articles identified, 655 were potentially eligible and 32 were included, reflecting 137 cases from 133 patients for the prognostic study and 154 cases from 150 patients for the surrogate study. The median glycolate concentration was 11.2 mmol/L (85.1 mg/dL, range 0-38.0 mmol/L, 0-288.8 mg/dL), 93% of patients were treated with antidotes, 80% received extracorporeal treatments, 49% developed acute kidney injury and 13% died. The glycolate concentration best predicting acute kidney injury was 12.9 mmol/L (98.0 mg/dL, sensitivity 78.5%, specificity 88.1%, positive predictive value 86.4%, negative predictive value 80.9%). The glycolate concentration threshold for a 95% negative predictive value for acute kidney injury was 6.6 mmol/L (50.2 mg/dL, sensitivity 96.9%, specificity 62.7%). The glycolate concentration best predicting mortality was 19.6 mmol/L (149.0 mg/dL, sensitivity 61.1%, specificity 81.4%, positive predictive value 33.3%, negative predictive value 93.2%). The glycolate concentration threshold for a 100% negative predictive value for mortality was 8.3 mmol/L (63.1 mg/dL, sensitivity 100.0%, specificity 35.6%). The glycolate concentration correlated best with the anion gap (R2 = 0.73), followed by bicarbonate (R2 = 0.57), pH (R2 = 0.50) and then base excess (R2 = 0.25), while there was no correlation between the glycolate and ethylene glycol concentration (R2 = 0.00). These data can assist clinicians in planning treatments such as extracorporeal treatments and prognostication. Potentially, they may also provide some reassurance regarding when extracorporeal treatments can be delayed while awaiting the results of further testing in patients in whom ethylene glycol poisoning is suspected but not yet confirmed. CONCLUSIONS: This systematic review demonstrates that the glycolate concentration predicts mortality (unlikely if <8 mmol/L [61 mg/dL]). The anion gap is a reasonable surrogate measurement for glycolate concentration in the context of ethylene glycol poisoning. The findings are mainly based on published retrospective data which have various limitations. Further prospective validation studies are of interest.

Analysis of Fomepizole Elimination in Methanol- and Ethylene Glycol-Poisoned Patients.

INTRODUCTION: Fomepizole is an anti-metabolite therapy that is used to diminish the toxicity from methanol or ethylene glycol. Although its elimination kinetics have been well described in healthy human subjects, the elimination in poisoned patients have only been described in a few isolated cases. This study was designed to relate the elimination of fomepizole in a series of poisoned patients to that in healthy humans. METHODS: Plasma samples from 26 patients in the clinical trials of the use of fomepizole for methanol and ethylene glycol poisoning were analyzed for fomepizole concentrations. The elimination of fomepizole was assessed after individual doses, both during and without intermittent hemodialysis. RESULTS: In methanol- and ethylene glycol-poisoned patients, fomepizole had a volume of distribution of 0.66-0.68 L/kg. After repeated doses of fomepizole, the minimum trough concentration averaged 86-109 µmol/L, which is 10 times higher than the minimum therapeutic concentration. In healthy human subjects, fomepizole elimination follows Michaelis-Menten kinetics and has been calculated as zero-order elimination rates. Zero-order elimination rates averaged 13 and 17 µmol/L/h in methanol and ethylene glycol patients, respectively, compared to 6-19 µmol/L/h in healthy subjects. Elimination during intermittent hemodialysis followed first-order kinetics, with a half-life of 3 h. CONCLUSIONS: Plasma concentrations during the repeated dosing confirmed that the recommended dosing schedule, with and without intermittent hemodialysis, maintained therapeutic concentrations throughout the treatments. Fomepizole elimination in poisoned patients at therapeutic plasma concentrations appears be similar to that reported previously in healthy human subjects.

Drug Misuse in Adolescents Presenting to the Emergency Department.

OBJECTIVES: Drug misuse is a disturbing, common practice among youth. One in 4 American adolescents reports consuming prescription medications without a clinical indication. We sought to explore current trends of drug misuse in adolescents. METHODS: Using the 37 participating sites of the ToxIC (Toxicology Investigators Consortium) Case Registry, a cross-country surveillance tool, we conducted an observational cohort study of all adolescents (aged 13-18 years) who presented to emergency departments with drug misuse and required a bedside medical toxicology consultation between January 2010 and June 2013. RESULTS: Of 3043 poisonings, 202 (7%) involved drug misuse (139 [69%] were males). Illicit drugs (primarily synthetic cannabinoids and "bath salts") were encountered in 101 (50%), followed by prescription medications (56 [28%]) and over-the-counter (OTC) drugs (51 [25%]). Dextromethorphan was the most commonly misused legal medication (24 [12%]). Polypharmacy exposure was documented in 74 (37%). One hundred sixty-three adolescents (81%) were symptomatic; of these, 81% had central nervous system impairments: psychosis (38%), agitation (30%), coma (26%), myoclonus (11%), and seizures (10%); and 66 (41%) displayed a specific toxidrome, most commonly sedative-hypnotic. Benzodiazepines were the most frequently administered medications (46%). Antidotes were administered to 28% of adolescents, primarily naloxone, physostigmine, N-acetyl-cysteine, and flumazenil. No deaths were recorded. CONCLUSIONS: Adolescents presenting with drug misuse may be exposed to a wide range and combinations of therapeutics or illicit substances and frequently display central nervous system abnormalities, compromising the ability to obtain a reliable history. Frontline clinicians should maintain a high index of suspicion, as routine toxicology screenings fail to detect most contemporary misused legal and designer drugs.

Commentary on the abuse of metal chelation therapy in patients with autism spectrum disorders.

Approximately half a million patients with autism spectrum disorders are subjected to chelation therapy in the US annually. The overwhelming majority of such cases are chelated for non-accepted medical indications. These patients may seek evaluation when a urine sample is assayed after the administration of a chelating agent and the values obtained have been improperly compared to references ranges for non-chelated urines, causing falsely elevated results. Legitimate practitioners confronted with such data must decide, preferably in consultation with the patient or their guardian(s), whether to do further testing using legitimate methodology or to simply dismiss the results of the improper testing. Bayesian principles tell us that further testing is likely to yield results within normal reference ranges. However, under some circumstances, it is useful to do such testing in order to demonstrate that there is no need for chelation therapy. Unnecessary chelation therapy is expensive, can cause significant acute adverse effects, and may be associated with long-term consequences.

The Toxicology Investigators Consortium Case Registry--the 2011 experience.

In 2010, the American College of Medical Toxicology established its Case Registry, the Toxicology Investigators Consortium (ToxIC). ToxIC is a prospective registry, which exclusively compiles suspected and confirmed toxic exposure cases cared for at the bedside by medical toxicologists at its participating sites. The Registry aims to fulfill two important gaps in the field: a real-time toxicosurveillance system to identify current poisoning trends and a powerful research tool in toxicology. ToxIC allows extraction of information from medical records making it the most robust multicenter database on chemical toxicities in existence. All cases seen by medical toxicologists at participating institutions were entered in a database. Information characterizing patients entered in 2011 was tabulated. 2010 data was also included so that cumulative total numbers could be described as well. The current report is a summary of the data collected in 2011 in comparison to 2010 entries and also includes cumulative data through December 31st, 2011. During 2011, 28 sites with 49 specific institutions contributed a total of 6,456 cases to the Registry. The total number of cases entered into the registry at the end of 2011 was 10,392. Emergency departments remained the most common source of consultations in 2011, accounting for 53 % of cases. The most common reason for consultation was for pharmaceutical overdoses, which occurred in 48 % of patients, including intentional (37 %) and unintentional (11 %) exposures. The most common classes of agents were sedative-hypnotics (1,492 entries in 23 % of cases), non-opioid analgesics (1,368 cases in 21 % of cases), opioids (17 %), antidepressants (16 %), stimulants/sympathomimetics (12 %), and ethanol (8 %). N-acetylcysteine was the most commonly administered antidote during 2011, similar to 2010, followed by the opioid antagonist naloxone, sodium bicarbonate, physostigmine and flumazenil. Anti-crotalid Fab fragments (CroFab) were administered in 106 out of 131 cases in which an envenomation occurred. There were 35 deaths recorded in the Registry during 2011. The most common associated agents, including when reported as sole agent or in combination with other agents, were opioids and analgesics (acetaminophen, aspirin, NSAIDS) with ten and eight deaths, respectively. Oxycodone was reported in six of the ten opioid-related deaths and heroin in three. Acetaminophen was the most common single agent reported overall being identified in all eight of the death cases attributed to analgesics. There were significant trends identified during 2011. Cases involving designer drugs including psychoactive bath salts and synthetic cannabinoids increased substantially from 2010 to 2011. The psychoactive bath salts were responsible for a large increase in stimulant/sympathomimetic-related cases reported to the Registry in 2011 with overall numbers doubling from 6 % of all Registry entries in 2010 to 12 % in 2011. Entries involving psychoactive drugs of abuse also increased twofold from 2010 to 2011 jumping 3 to 6 %, primarily due to increasing frequency of synthetic cannabinoid ("K2") related intoxications as 2011 progressed. The 2011 Registry included over 600 ADR's (10 % of Registry Cases) with 115 agents causing at least 2 ADR's. This is up from only 3 % of cases (116 total cases) in 2010. The ToxIC Case Registry continues to grow. At the end of 2011, over 10,000 cases had been entered into the Registry. As demonstrated by the trends identified in psychoactive bath salt and synthetic cannabinoid reports, the Registry is a valuable toxicosurveillance and research tool. The ToxIC Registry is a unique tool for identifying and characterizing confirmed cases of significant or potential toxicity or complexity to require bedside consultation by a medical toxicologist.

Fomepizole for the treatment of pediatric ethylene and diethylene glycol, butoxyethanol, and methanol poisonings.

INTRODUCTION: The use and clinical efficacy of the alcohol dehydrogenase inhibitor fomepizole is well established for the treatment of ethylene glycol and methanol poisonings in adults. METHODS: A computerized search of the U.S. National Academy of medicine and EMBase databases was undertaken to identify published cases of patients treated with fomepizole. This search strategy identified 14 published cases related to the topic of this review: 10 due to ethylene glycol poisoning, 1 due to diethylene glycol poisoning, 1 due to butoxyethanol ingestion, and 2 due to methanol poisoning. The median age of these cases was 5.5 years old. FOMEPIZOLE IN GLYCOL AND GLYCOL ETHER POISONING: For the 10 ethylene glycol poisoned patients, the median recorded values of their arterial pH was 7.27 (range 7.03-7.38), serum bicarbonate concentration was 13 mEq/L (range 2-25), and ethylene glycol concentration was 2,140 mg/L (range 130-3,840). Eight of these patients were not hemodialyzed. The eight patients who were not hemodialyzed had ethylene glycol concentrations as high as 3,500 mg/L and serum bicarbonate concentrations as low as 4 mEq/L. All 10 patients had resolution of their metabolic acidosis and recovered without sequelae. The half-times of ethylene glycol elimination ranged from 9 to 15 h during fomepizole therapy, which is faster than the 19.7 h reported in adults. The two patients who ingested diethylene glycol or butoxyethanol all recovered without sequelae. The patient who ingested the butoxyethanol had a serum bicarbonate concentration of 13 mEq/L and was not hemodialyzed. FOMEPIZOLE IN METHANOL POISONING: One of the two children who ingested methanol was hemodialyzed. Both cases had a similar degree of severity. DOES FOMEPIZOLE OBVIATE THE NEED FOR HEMODIALYSIS?: Based on the experience reviewed herein it appears that, as in adults, hemodialysis may not be necessary in most cases of pediatric ethylene glycol poisoning if treated with fomepizole. FOMEPIZOLE PHARMACOKINETICS: Plasma fomepizole concentrations were measured in three cases and were found to be therapeutic with apparent Michaelis-Menton kinetics, having a zero-order elimination rate of 0.6-1 mg/L/h at higher concentrations and a first-order elimination with an apparent elimination half-time of 3.9 h at lower concentrations. FOMEPIZOLE REGIMEN: Most cases used the current U.S.-approved regimen. ADVERSE EFFECTS OF FOMEPIZOLE: The one adverse effect reported during fomepizole therapy was transient nystagmus in a 6-year-old with a serum ethylene glycol concentration of 130 mg/L and a serum bicarbonate concentration of 2 mEq/L; it is likely that ethylene glycol itself was the cause. COMPARISON OF FOMEPIZOLE WITH ETHANOL THERAPY: Two cases were originally treated with ethanol but switched to fomepizole because of adverse effects. In both cases, the adverse reactions to ethanol resolved once fomepizole treatment was initiated. CONCLUSIONS: The limited data available suggest that fomepizole, using the same dosage regimen as that used for adults, is efficacious and well tolerated in pediatric patients. In many cases of pediatric ethylene glycol poisoning treated with fomepizole, hemodialysis may not be necessary despite high concentrations and the presence of metabolic acidosis.

Massive ethylene glycol ingestion treated with fomepizole alone-a viable therapeutic option.

Fomepizole is used to treat and prevent toxicity from ethylene glycol poisoning. Treatment with fomepizole without hemodialysis in massive ethylene glycol ingestion has been rarely reported in the literature; however, published literature and practice guidelines recommend considering dialysis for ethylene glycol levels >50 mg/dL. We report a case of massive ethylene glycol ingestion resulting in the highest serum ethylene glycol concentration in a patient without ethanol co-ingestion who was treated with fomepizole and was not hemodialyzed. A 48-year-old male presented to the emergency department after reportedly ingesting >1 liter of antifreeze in an attempt at self-harm. He denied concomitant ethanol consumption. His initial presenting serum ethylene glycol level was 700 mg/dL, with normal renal function, and a metabolic acidosis with a high anion gap. One hour after presentation, he was started on intravenous fomepizole. Treatment with fomepizole continued until the patient's plasma ethylene glycol concentration was 16 mg/dL. His metabolic acidosis quickly resolved, he had no adverse reactions to the treatment, and his renal function remained normal. Ultimately, he was discharged to a psychiatric unit without sequelae. Published literature and practice guidelines suggests considering hemodialysis initiation in patients with an ethylene glycol level > 50 mg/dL. This recommendation is anecdotally, rather than evidence, based. With the potential risks inherent in hemodialysis, our case provides evidence that treatment with fomepizole without hemodialysis appears to be a viable alternative option in patients with even extremely high plasma ethylene glycol concentrations as long as their renal function is intact.

Derivation of a chemical-specific adjustment factor (CSAF) for use in the assessment of risk from chronic exposure to ethylene glycol: application of International Programme for Chemical Safety guidelines.

The International Programme for Chemical Safety (IPCS) has developed a set of guidelines ("the Guidance") for the establishment of Chemical-Specific Adjustment Factors (CSAFs) for in the assessment of toxicity risk to the human population as a result of chemical exposure. The development of case studies is encouraged in the Guidance document and comments on them have been encouraged by the IPCS. One provision in the Guidance is for the determination of CSAFs based on human data. We present a case study of the use of the Guidance for the determination of the CSAF for ethylene glycol (EG) primarily utilizing clinically obtained data. The most relevant endpoint for this analysis was deemed to be acute renal injury. These data were applied based on an assessment of the known pharmaco/toxico-kinetic properties of EG. Because of the lack of both bioaccumulation of EG and reports of chronic or progressive renal injury from EG, it was concluded that the most appropriate model of chronic exposure is one of repeated acute episodes. The most relevant exposure metric was determined to be plasma glycolate concentration. Based on a prospective human study of EG-poisoned patients, the NOAEL for glycolate was found to be 10.1 mM. This value is similar to that obtained from animal data. The application of the Guidelines to this data resulted in a CSAF of 10.24, corresponding to a daily EG dose of 43.7 mg/kg/day. In 2000, Health Canada (HC) produced an animal data-based analysis of the maximum tolerated dose of EG. The results of our analysis are compared with those of HC, and the strengths and weaknesses of these two data types related to EG are discussed.

Toxicokinetics of ethylene glycol during fomepizole therapy: Implications for management.

STUDY OBJECTIVE: The elimination kinetics of ethylene glycol (EG) in human subjects treated with fomepizole (4-methylpyrazole) were analyzed to establish the efficacy of alcohol dehydrogenase (ADH) inhibition and to characterize elimination pathways. METHODS: Drug concentration data from patients enrolled in the EG arm of the Methylpyrazole for Toxic Alcohols trial, a prospective, multicenter, open-label trial of fomepizole, were analyzed and compared with published estimates. RESULTS: In 19 patients analyzed (EG concentrations of 3.5 to 211 mg/dL), elimination was first order during fomepizole monotherapy (half-life of 19.7±1.3 hours) and was not affected by the presence of ethanol. The elimination rate was significantly faster (half-life of <8.6±1.1 hours, P <.001) in the absence of fomepizole and ethanol. EG elimination by the kidneys was directly proportional to remaining renal function as estimated by creatinine clearance, with a fractional excretion of 25.5%±9.4%. Renal elimination and hemodialysis were the only significant routes of EG elimination as long as fomepizole concentrations were maintained well above 10 µmol/L (EG/fomepizole molar ratio, <100:1). All patients with normal serum creatinine concentrations at the initiation of fomepizole treatment had rapid rates of renal elimination (half-life of 16.8±0.8 hours). CONCLUSION: At doses used, fomepizole effectively inhibits ADH-mediated metabolism of EG. Serum creatinine concentration at presentation and creatinine clearance can be used to predict EG elimination during fomepizole therapy and can help determine which patients will require hemodialysis to expedite EG elimination. An absolute EG concentration above 50 mg/dL should no longer be used as an independent criterion for hemodialysis in patients treated with fomepizole. [Sivilotti MLA, Burns MJ, McMartin KE, Brent J, for the Methylpyrazole for Toxic Alcohols Study Group. Toxicokinetics of ethylene glycol during fomepizole therapy: implications for management. Ann Emerg Med. August 2000;36:114-125.].