Pharmacokinetic-pharmacodynamic modelling of QT interval prolongation following citalopram overdoses

AIMS: To develop a pharmacokinetic-pharmacodynamic model describing the time-course of QT interval prolongation after citalopram overdose and to evaluate the effect of charcoal on the relative risk of developing abnormal QT and heart-rate combinations. METHODS: Plasma concentrations and electrocardiograph (ECG) data from 52 patients after 62 citalopram overdose events were analysed in WinBUGS using a Bayesian approach. The reported doses ranged from 20 to 1700 mg and on 17 of the events a single dose of activated charcoal was administered. The developed pharmacokinetic-pharmacodynamic model was used for predicting the probability of having abnormal combinations of QT-RR, which was assumed to be related to an increased risk for torsade de pointes (TdP). RESULTS: The absolute QT interval was related to the observed heart rate with an estimated individual heart-rate correction factor [alpha = 0.36, between-subject coefficient of variation (CV) = 29%]. The heart-rate corrected QT interval was linearly dependent on the predicted citalopram concentration (slope = 40 ms l mg(-1), between-subject CV = 70%) in a hypothetical effect-compartment (half-life of effect-delay = 1.4 h). The heart-rate corrected QT was predicted to be higher in women than in men and to increase with age. Administration of activated charcoal resulted in a pronounced reduction of the QT prolongation and was shown to reduce the risk of having abnormal combinations of QT-RR by approximately 60% for citalopram doses above 600 mg. CONCLUSION: Citalopram caused a delayed lengthening of the QT interval. Administration of activated charcoal was shown to reduce the risk that the QT interval exceeds a previously defined threshold and therefore is expected to reduce the risk of TdP.     

Seizures in a pediatric patient with a tiagabine overdose

Introduction

Tiagabine (TGB) is a novel antiepileptic that decreases GABA uptake. The literature contains one report of an adult with epilepsy who ingested up to 1 gram of TGB and developed status epilepticus. We reported on a pediatric patient who ingested significantly less TGB but still developed tonic-clonic seizures.

Case report

A previously healthy, 13 kg, two-year-old girl developed generalized tonic-clonic seizure activity at home approximately 1 hour after ingesting 90 mg of her grandmother’s TGB (forty five 2 mg tablets). At the hospital she had two 5 minute seizures at 1.5 and 3.5 hours post ingestion. Her serum TGB levels were 530 and 130 ng/ml approximately 5 and 11 hours post-ingestion (5–70 ng/ml trough levels with most probable range for seizure control). She was discharged 27 hours post ingestion, and she was in good condition.

Conclusion

An overdose of TGB, a novel anti-epileptic, can cause convulsive seizures.     

Risperidone, QTc interval prolongation, and torsade de pointes: a systematic review of case reports

Rationale

A recent publication asserted that even low-dose risperidone may induce corrected QT (QTc) interval prolongation up to 500 ms without drug-induced I_Kr blockade. We seek to better understand the complexity of any link between risperidone-induced/associated QTc interval prolongation and torsade de pointes (TdP).

Objectives

The objective of this study is to systematically analyze all available case reports of risperidone, QTc interval prolongation, and/or TdP.

Method

We identify case reports using PubMed, Medline, EMBASE, and Cochrane.

Results

Of the 15 cases found, nine were adult women (ages 31, 33, 34, 37, 47, “elderly”, 77, 84, and 87 years) and one was a teenager. There were four men (ages 28, 29, 29, and 46 years) and one preadolescent boy. Besides risperidone administration or overdose, traditional risk factors for QTc interval prolongation and TdP included female sex (n?=?10), older age (n?=?4), heart disease (n?=?3), hypokalemia (n?=?2), bradycardia (n?=?1), liver disease (n?=?1), QTc interval prolonging drugs other than risperidone (n?=?8), and metabolic inhibitors (n?=?2). TdP occurred in four cases. Six patients died, and three deaths were probably related to TdP.

Conclusion

Risperidone (when properly prescribed in patients free of other risk factors for QTc interval prolongation and TdP) is a relatively safe drug. Conventional statistics can neither predict the individual patient who will experience TdP nor determine the relationship of drug dose to QTc interval prolongation and TdP. Narrative medicine using a case report format appears to be an alternative and valuable additional approach to advance our understanding of this relationship and to reduce risks.     

Asymptomatic QTc prolongation associated with quetiapine fumarate overdose in a patient being treated with risperidone

We report a patient who ingested a 2000-mg overdose of quetiapine fumarate (Seroquel). Her maintenance medications also included risperidone, venlafaxine, topiramate, and clonazepam. On presentation, she was drowsy, but had no other significant CNS signs and no cardiac symptoms or abnormal physical signs. Approximately 2 h after the quetiapine ingestion, an electrocardiogram (ECG) showed normal sinus rhythm at 95 beats/min with a corrected QT (QTc) interval of 537 ms (upper limit of normal = 440 ms). Plasma quetiapine concentration at that time was 1800 ng/ml. Continuous ECG monitoring for the subsequent 18 h did not reveal any episode of ventricular tachycardia. A 12-lead ECG 18 h post-overdose was normal with a QTc interval of 401 ms and the corresponding plasma quetiapine concentration was 160 ng/ml. She made an uneventful medical recovery from the toxic ingestion. This case suggests that when patients overdose on quetiapine while taking therapeutic doses of risperidone, such overdoses, even if not massive, can cause considerable QTc interval prolongation. We recommend that quetiapine overdose patients undergo continuous ECG monitoring for 12-18 h post-ingestion.     

A fatal case of venlafaxine overdose

Introduction

Based on its primary action of serotonin reuptake inhibition, venlafaxine overdose would be expected to result in serotonergic effects.

Case Report

A 40 year old male ingested venlafaxine without co-ingestants in a suicide attempt. The patient developed refractory ventricular fibrillation and expired approximately 9 hours post-ingestion. ECG monitoring revealed significant QRS and QT_C interval prolongation prior to his demise.

Discussion

A literature review of venlafaxine overdose cases and investigation into its mechanism of action was conducted. The potential for sodium channel blockade and implications for therapy are discussed.     

Adult respiratory distress syndrome and renal failure associated with citalopram overdose

A 45-year-old man ingested 3000 mg of citalopram hydrobromide (2400 mg citalopram). He presented to the Emergency Department 2 hours post-ingestion with a pulse of 100 beats/min and blood pressure of 120/80 mmHg. His electrocardiogram (ECG) was normal. Chest X-ray showed bilateral shadowing, with no evidence of aspiration of gastric contents. Shortly after, he had three tonic-clonic seizures, requiring intravenous diazepam. Eight hours post-ingestion he became oliguric with deteriorating renal function, despite normal arterial and central venous pressures. He became increasingly hypoxic, with chest X-ray changes compatible with adult respiratory distress syndrome (ARDS). Despite treatment with 100% oxygen and continuous positive airway pressure, his gas exchange continued to deteriorate, requiring intubation and ventilation. His renal function also deteriorated with a peak creatinine of 492 micromol/L on day 4 in the absence of rhabdomyolysis. There was complete spontaneous recovery of renal function after 2 weeks. A peak plasma total citalopram (R+S enantiomers) concentration of 1.92 mg/L was recorded 2 hours post-ingestion. Total norcitalopram concentrations continued to rise up to 24 hours post-ingestion. Citalopram has been associated with seizures, ECG abnormalities, rhabdomyolysis and coma after overdose. The renal and respiratory complications seen in this patient have not been reported previously.     

The role of adenosine receptors and endogenous adenosine in citalopram-induced cardiovascular toxicity

Aim:

We investigated the role of adenosine in citalopram-induced cardiotoxicity.

Materials and Methods:

Protocol 1: Rats were randomized into four groups. Sodium cromoglycate was administered to rats. Citalopram was infused after the 5% dextrose, 8-Cyclopentyl-1,3-dipropylxanthine (DPCPX; A₁ receptor antagonist), 8-(-3-chlorostyryl)-caffeine (CSC; A_2a receptor antagonist), or dimethyl sulfoxide (DMSO) administrations. Protocol 2: First group received 5% dextrose intraperitoneally 1 hour prior to citalopram. Other rats were pretreated with erythro-9-(2-hydroxy-3-nonyl) adenine (EHNA; inhibitor of adenosine deaminase) and S-(4-Nitrobenzyl)-6-thioinosine (NBTI; inhibitor of facilitated adenosine transport). After pretreatment, group 2 received 5% dextrose and group 3 received citalopram. Adenosine concentrations, mean arterial pressure (MAP), heart rate (HR), QRS duration and QT interval were evaluated.

Results:

In the dextrose group, citalopram infusion caused a significant decrease in MAP and HR and caused a significant prolongation in QRS and QT. DPCPX infusion significantly prevented the prolongation of the QT interval when compared to control. In the second protocol, citalopram infusion did not cause a significant change in plasma adenosine concentrations, but a significant increase observed in EHNA/NBTI groups. In EHNA/NBTI groups, citalopram-induced MAP and HR reductions, QRS and QT prolongations were more significant than the dextrose group.

Conclusions:

Citalopram may lead to QT prolongation by stimulating adenosine A₁ receptors without affecting the release of adenosine.KEY WORDS: Adenosine receptor, citalopram toxicity, endogenous adenosine, QT prolongation, rat     

Delayed dystonia following pimozide overdose in a child

BACKGROUND: Pimozide overdose has rarely been reported in children. In adults, pimozide intoxication may cause seizures, extrapyramidal and anticholinergic effects, hypotension, QTc prolongation and torsades de pointes. We report dystonia, hypotension and drowsiness following pimozide ingestion in a child. CASE REPORT: An alert 18-month-old presented to hospital 40 minutes after ingesting up to 6 mg (0.5 mg/kg) of pimozide. Vital signs: BP 91/62 mmHg, HR 130/min, RR 26/min, temperature 97.2 degrees F (36.2 degrees C). She received gastric lavage and activated charcoal. One hour later, her QTc interval was 420 msec, HR 150. She remained asymptomatic until 12 hours post-ingestion, when she developed drooling, tongue thrusting and drowsiness. BP was 75/40, HR 150, QTc 440 msec. BP increased to 95/50 after a bolus of normal saline. Her dystonia subsided over the next 12 hours without treatment. Drowsiness and tachycardia persisted until 40 hours post-ingestion. QTc interval at this time was 370 msec. Patient recovered without sequelae. CONCLUSION: Pimozide overdose in children may be associated with delayed onset of symptoms, including dystonia.     

Comparative toxicity of citalopram and the newer antidepressants after overdose

OBJECTIVE: To compare the toxicity of citalopram, venlafaxine, mirtazapine, and nefazadone after overdose. METHODS: Two-year retrospective review of consecutive patients admitted to the toxicology unit of Edinburgh Royal Infirmary. Outcome measure included physiological variables, ECG recordings, peak creatine kinase, development of arrhythmias, seizure, tremor or agitation, and the need for admission to a critical care facility. RESULTS: A total of 225 patients were studied. Venlafaxine was associated with a significantly higher pulse rate (p < 0.0001) and tremor (p = 0.007) than other antidepressants. Citalopram was associated with a significantly longer QT interval on ECG recording (p < 0.0001) but mean QTc durations were not significantly different between all drugs studied. No arrhythmias were recorded. Only venlafaxine and citalopram caused seizures and were associated with the need for admission to Intensive Care, but there was no significant difference between them. CONCLUSIONS: Mirtazapine and nefazadone appear safe in overdose and were associated with minimal features of neurological or cardiovascular toxicity. Citalopram is more likely to cause QT prolongation but other features of cardiovascular toxicity were uncommon. Both citalopram and venlafaxine are proconvulsants. Venlafaxine also causes more frequent features of the serotonin syndrome.     

A new preclinical biomarker for risk of Torsades de Pointes: drug-induced reduction of the cardiac electromechanical window

Evaluation of new therapeutic agents for their potential to cause QT interval prolongation and drug-induced ventricular arrhythmia, like Torsades de Pointes (TdP), is a critical activity during drug development. The QT interval has been used as a surrogate biomarker to assess ventricular repolarization effects caused by drug-induced blockade of cardiac repolarizing currents, mainly I_Kr, but is imperfect in predicting proarrhythmia. Evidence suggests that left ventricular mechanical dysfunction may also contribute to ventricular arrhythmias; thus, electrical and mechanical alterations may have a role in drug-induced TdP. The electromechanical window (EMw) represents the time difference between the end of electrical systole (i.e. the QT interval) and the completion of ventricular relaxation (i.e. the QLVP_end interval), and appears to be a new potential biomarker for TdP risk. A reduction in the EMw (to negative values) has now been shown to be associated with the onset of TdP in an anaesthetized dog model of long QT1 syndrome. Therefore, the EMw represents a novel indicator of TdP risk that may add predictive value beyond assay of drug-induced QT interval prolongation.

LINKED ARTICLE

This article is a commentary on van der Linde et al., pp. 1444–1454 of this issue. To view this paper visit http://dx.doi.org/10.1111/j.1476-5381.2010.00934.x     

Orthotopic liver transplants necessitated by acetaminophen-induced hepatotoxicity.

BACKGROUND: Acetaminophen-induced hepatotoxicity has been recognized since 1966. Patients experiencing a massive hepatic insult due to acetaminophen (APAP) may recover with minimal residual complications or develop fulminant hepatic necrosis. We report 3 patients with hepatic failure due to an APAP overdose who received orthotopic liver transplants and survived. CASE REPORTS: An 18-y-o female ingested 60 500 mg APAP tablets (30 g). She presented with tachycardia and lethargy stating that she had taken amoxipine, carbamazepine, and lorazepam. She began to recover but on day 2 experienced an upper gastrointestinal bleed and became hypotensive and hyperpyrexic. She developed hepatic encephalopathy and it was then determined she had ingested APAP. Her APAP level was 13 micrograms/ml 96 h post-ingestion. She was successfully transplanted 19 d post-ingestion with recovery. A 40-y-o female was admitted for flu-like symptoms persisting for 7 d. She was jaundiced, hyperventilating and hypotensive. She admitted ingesting approximately 17 g APAP over 36 h. Her APAP level was 12.2 micrograms/ml. Her condition worsened and on day 3 she was in grade IV coma. She was successfully transplanted 4 d post-arrival with recovery. A 16-y-o female ingested an unknown amount of APAP. She presented approximately 24 h post-ingestion with a serum APAP level of 130 micrograms/ml. Her condition deteriorated and she became encephalopathic with grade IV coma. She was successfully transplanted on day 7 post-arrival. DISCUSSION: Hepatotoxicity can occur as a result of either acute or chronic APAP overdose. Although n-acetylcysteine (NAC) is effective antidotal therapy, it must be used within 8-12 h post-ingestion to be optimally effective. Inaccurate patient histories may prevent NAC administration resulting in hepatotoxicity. CONCLUSION: Liver transplantation is a viable option to be considered in those APAP overdose patients who experience rapidly progressing encephalopathy, hemolysis, and hepato-renal failure.     

Predictive factors for generalized seizures after deliberate citalopram overdose

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

• Citalopram is a common means of self-poisoning in young adults.
• Generalized seizures are a recognised complication after selective serotonin reuptake inhibitor overdose (including citalopram overdose).

WHAT THIS STUDY ADDS

• The minimum stated citalopram dose associated with seizures in the absence of co-ingested drugs was 400 mg.
• Co-ingestion of a tricyclic antidepressant or venlafaxine confers a 15-fold increased risk of seizures.

AIMS

Seizures are a recognized complication of citalopram overdose. The present study sought to establish risk factors for seizures in this high-risk patient group, including stated dose ingested, co-ingested drugs or ethanol, and electrolyte disturbances.

METHODS

A retrospective casenote review was carried out of patients who attended the Emergency Department due to citalopram overdose between January 2000 and July 2007 inclusive. Stepwise logistic regression analysis considered age, gender, stated citalopram dose, acute ethanol consumption, co-ingested drugs, administration of activated charcoal, and hyponatraemia.

RESULTS

There were 241 patients (177 women), and the median (interquartile range) stated citalopram dose was 300 mg (200 to 600 mg). Generalized seizures occurred in 18 patients (7.5%). Logistic regression analysis found co-ingested tricyclic antidepressants or venlafaxine predicted seizures with odds ratio = 15 (95% confidence interval 3, 75). In the absence of co-ingested drugs, the minimum citalopram dose associated with seizures was 400 mg. Odds ratio for seizures = 1.1 (95% confidence interval 1.0, 1.2) for every 100 mg increment in citalopram dose. Seizures were associated with a greater need for invasive ventilatory support, higher creatine kinase activity, and prolonged hospital stay.

CONCLUSIONS

Generalized seizures are an important manifestation of citalopram toxicity, and cannot be explained solely by electrolyte disturbances or co-ingestion of other drugs or ethanol. The strongest predictors of seizures in this patient series were ingestion of high citalopram dosages and co-ingestion of drugs capable of lowering seizure threshold.     

Deliberate Fingolimod Overdose Presenting with Delayed Hypotension and Bradycardia Responsive to Atropine

Introduction

Fingolimod is an immunomodulating agent used in multiple sclerosis (MS). It is a sphingosine-1-phosphate (S1P) receptor agonist prescribed for relapsing forms of MS to delay onset of physical disability. As fingolimod is known to cause first-dose bradycardia, telemetry is recommended for the first 6 h post-dose. We present the first reported case of deliberate fingolimod overdose requiring atropine administration for bradycardia and hemodynamic instability.

Case report

A 33-year-old woman ingested 14 mg of fingolimod and 2 g of phenoxymethylpenicillin. After presenting to the emergency department 19 h later, she was initially hemodynamically stable (heart rate (HR) 60, blood pressure (BP) 113/89 mmHg). Two hours later, she then developed bradycardia (HR 48) and hypotension (87/57 mmHg). Despite intravenous fluids, stabilisation was only achieved after administration of atropine (300 μg). She was then admitted to the intensive care unit (ICU) for further monitoring where another episode of bradycardia and hypotension required atropine. She was monitored in the ICU for 48 h and then discharged on day 5 with no further episodes.

Discussion

Fingolimod is known to cause bradycardia in the first 6 h post first therapeutic dose. Following intentional overdose, onset of bradycardia occurred at 21 h post-ingestion and was associated with hypotension. Atropine was successful in treating bradycardia and associated hypotension.     

A report of two deaths from massive ibuprofen ingestion

Introduction

Ibuprofen is a commonly used non-steroidal anti-inflammatory drug. While the vast majority of exposures to the drug do not result in significant morbidity, we are reporting 2 fatalities that resulted from massive ibuprofen ingestion.

Case 1

A 17-year-old girl presented to the emergency department (ED) following an ibuprofen overdose; she was unresponsive with a metabolic acidosis and hypothermic. Her serum ibuprofen concentration was 352 μg/mL: the therapeutic range is 10–50 μg/mL. Despite intensive supportive care and continuous veno-venous hemofiltration, she expired.

Case 2

A 49-year-old man presents to the ED with a history of divalproex sodium and ibuprofen ingestion. He was unresponsive, hypotensive, and had a significant metabolic acidosis. His serum ibuprofen concentration was 260 μg/mL and serum valproate concentration was 560 μg/mL: the therapeutic range is 50–100 μg/mL. In spite of supportive care and hemodialysis, he expired.

Discussion

We will describe 2 cases of ibuprofen overdose characterized by cardiovascular collapse, acidosis, and hypothermia despite the use of vasopressors and renal replacement therapy. Although rarely reported, massive ibuprofen overdose may result in refractory multisystem organ failure and death.     

Toxicity from a clonidine suspension

Background

Clonidine is frequently prescribed to children. Clonidine overdose in children has resulted in major clinical effects and deaths.

Case Report

A 3.5-year-old male with a history of a seizure disorder and night terrors presented following difficulty walking, excessive sleeping, agitation when awake, and possible seizure activity. Chronic medications were valproic acid (VPA) and clonidine. On presentation, he alternated between poor responsiveness and agitation, with initial vitals: blood pressure, BP 144/76 mmHg; heart rate, 65 bpm; respiratory rate, 18 bpm; temperature 99.5°F; and pulse oximetry 96% on room air. VPA level was 35 μg/mL. A toxicology consult the next day noted a dry mouth, 2-mm pupils, intermittent gasping, and central nervous system (CNS) depression, with a diagnostic impression of clonidine overdose. The caregiver had been giving 1 mL (0.1 mg) qd of a pharmacy-compounded clonidine suspension by a provided syringe. The pharmacy procedure record agreed with the physicians order. The amount dispensed was a 30-day supply but the bottle was empty on day 19, leading us to suspect a possible accelerated dosing error. The concentration in the bottle thus could not be confirmed. The child slowly returned to his baseline state over 48 hours. A serum clonidine level drawn approximately 18 hours after his last dose later returned at 300 ng/mL (reference range = 0.5–4.5 ng/mL).

Case Discussion

Compounding and liquid dosing errors are common in children and may result in massive overdoses. There was an accelerated dosing error, but whether a compounding or suspension error or even an acute overdose occurred as well is unknown.

Conclusion

Particular care should be taken with medications that have low therapeutic indices, that are extemporaneously compounded, and are prepared as liquids, where medication errors are more likely.     

Late-onset seizures associated with quetiapine poisoning

Introduction

Quetiapine, a second-generation antipsychotic, acts at multiple brain neurotransmitter receptors and has the potential for serious complications. Although seizures have been described in the literature, delayed seizure onset has not been reported. We report the first case of delayed seizures after a significant quetiapine overdose.

Case Report

A 27-year-old female presented to the emergency department following an overdose of approximately 30 g of quetiapine. Twenty-four hours after arrival, the patient had 2 seizures. The patient was then intubated and remained in the ICU for four days. EEG was negative for epileptiform activity. The serum quetiapine levels (MedTox, St. Paul, MN) were 8.67 mg/L on hospital day one and 3.28 mg/L on hospital day three.

Discussion

Quetiapine poisoning, with serum levels, associated with seizures has been reported in one prior case. Our case report represents late-onset seizures with serum levels above therapeutic range (> 1 mg/L). The serum concentrations of quetiapine in this case were consistent with those in postmortem case reports.     

Evaluation of a QT nomogram for risk assessment after antidepressant overdose

AIMS

A QT-heart rate nomogram has recently been proposed as a means of identifying patients at risk of torsades de pointes after antidepressant overdose, based on published cases of drug-induced torsades de pointes. The present study sought to examine the performance of the nomogram in patients who ingest an antidepressant overdose but do not develop arrhythmia.

METHODS

A retrospective case control study of patients presenting to hospital after overdose of citalopram, mirtazapine and venlafaxine was carried out. The primary outcome variable was QT higher than the nomogram, and was compared with occurrence of QT_c (QT corrected by Bazett''s formula) greater than ≥440 ms and QT_c≥500 ms, with comparison between drugs. Data are expressed as proportions in each group with 95% confidence intervals.

RESULTS

There were 858 electrocardiograms from 541 patients. QT was higher than the nomogram in 2.4% (1.4, 4.1%), whereas QT_c was ≥440 ms in 23.1% (95% CI 19.8, 26.8%), and QT_c was ≥500 ms in 1.1% (0.5, 2.5%). Citalopram overdose was more likely to be associated with QT higher than the nomogram compared with the other agents (difference 7.0%, 95% CI 2.9, 11.9%, P = 0.001) and more likely to be associated with QT_c≥440 ms (difference = 11.0%, 95% CI 2.6, 19.0%, P = 0.013).

CONCLUSIONS

The QT nomogram was associated with a lower false positive rate than widely accepted QT_c criteria, and allowed detection of different effects of individual drugs. The nomogram offers potential advantages over QT_c criteria and merits further investigation in a clinical setting.     

The electro-mechanical window in anaesthetized guinea pigs: a new marker in screening for Torsade de Pointes risk

BACKGROUND AND PURPOSE

QT prolongation is commonly used as a surrogate marker for Torsade de Pointes (TdP) risk of non-cardiovascular drugs. However, use of this indirect marker often leads to misinterpretation of the realistic TdP risk, as tested compounds may cause QT prolongation without evoking TdP in humans. A negative electro-mechanical (E-M) window has recently been proposed as an alternative risk marker for TdP in a canine LQT1 model. Here, we evaluated the E-M window in anaesthetized guinea pigs as a screening marker for TdP in humans.

EXPERIMENTAL APPROACH

The effects of various reference drugs and changes in body temperature on the E-M window were assessed in instrumented guinea pigs. The E-M window was defined as the delay between the duration of the electrical (QT interval) and mechanical (QLVP_end) systole.

KEY RESULTS

Drugs with known TdP liability (quinidine, haloperidol, domperidone, terfenadine, thioridazine and dofetilide), but not those with no TdP risk in humans (salbutamol and diltiazem) consistently decreased the E-M window. Interestingly, drugs with known clinical QT prolongation, but with low risk for TdP (amiodarone, moxifloxacin and ciprofloxacin) did not decrease the E-M window. Furthermore, the E-M window was minimally affected by changes in heart rate or body temperature.

CONCLUSIONS AND IMPLICATIONS

A decreased E-M window was consistently observed with drugs already known to have high TdP risk, but not with drugs with low or no TdP risk. These results suggest that the E-M window in anaesthetized guinea pigs is a risk marker for TdP in humans.     

Delayed immunosuppressive treatment in life-threatening paraquat ingestion: A case report

Introduction

Combined glucocorticoids and cyclophosphamide pulse therapy showed promising results in moderate-to-severe paraquat poisonings to reduce life-threatening respiratory complications. Its benefit has been observed when given early in the course of poisoning; however, whether its delayed administration remains beneficial is unknown.

Case Report

We describe a 23-year-old male who ingested 70 mL of a commercialized concentrate formulation with 20% weight/volume paraquat in a suicide attempt. Within 24 hours from paraquat ingestion, he presented most of the indicators of poor outcome, including gastritis, early renal dysfunction, dark blue urine colorimetric dithionite test, and marked plasma paraquat concentrations (0.56 μg/mL at 13 hours, and 0.41 μg/mL at 24 hours after ingestion). The patient received early gastrointestinal decontamination and aggressive supportive treatments. However, due to a rapidly progressive severe pulmonary infection, glucocorticoids and cyclophosphamide were delayed until day 14. Interestingly, our patient survived with mild respiratory sequelae despite poor initial prognosis.

Discussion

This observation suggests the potential benefit of immunosuppressive pulse therapy, even if administered 14 days after paraquat ingestion, and highlights the role of paraquat-induced alveolitis in the development of fibrosis.

Conclusion

Combined glucocorticoids and cyclophosphamide should be considered in moderate-to-severe paraquat poisonings, even if delayed.