Hypotension in severe tricyclic antidepressant overdose

Dual effect of amitriptyline in the control of vascular tone: Direct blockade of calcium channel in smooth muscle cells and reduction of TLR4-dependent NO production in endothelial cells

BACKGROUND AND PURPOSE

Amitriptyline (AM) is a classical and typical tricyclic antidepressant drug. Despite its well-known effects on the nervous system, it has been described to work as a TLR4 antagonist and several clinical works suggested some unexpected cardiovascular effects. The role of amitriptyline on vascular tone is not clear, thus we hypothesized that amitriptyline has a double effect on vascular tone by both endothelial TLR4-dependent nitric oxide down-regulation and calcium channel blockade in smooth muscle cells.

EXPERIMENTAL APPROACH

Changes in isometric tension were recorded on a wire myograph. NO production was evaluated by fluorescence microscopy and flow cytometry in the mouse aorta and EAhy926 cells using DAF fluorescence intensity. Calcium influx was evaluated in A7r5 cells by flow cytometry. Western blot was used to analyze eNOS and nNOS phosphorylation.

KEY RESULTS

AM reduced PE-induced contraction by calcium influx diminution in smooth muscle cells (F/F₀ = 225.6 ± 15.9 and 118.6 ± 17.6 to CT and AM, respectively). AM impaired Ach-dependent vasodilation (Emax = 95.8 ± 1.4; 78.1 ± 1.8; 60.4 ± 2.9 and -7.4 ± 1.0 for CT, 0.01, 0,1 and 1 μmol/L AM, respectively) through reduction of calcium influx and NO availability and TLR4 antagonism in a concentration-dependent manner. AM or TLR4 gene deletion significantly reduced NO production (Fluorescence = 9503 ± 871.7, 2561 ± 282, 4771 ± 728 and 1029 ± 103 to CT, AM, TLR4^-/- and AM + TLR4^-/-, respectively) by an increase in nNOS^ser852 and reduction in eNOS^ser1177 phosphorylation in endothelial cells.

CONCLUSIONS AND IMPLICATIONS

Our data show that amitriptyline impaired vascular function through two different mechanisms: blockade of TLR4 in endothelial cells and consequent decrease in NO production and calcium influx reduction in smooth muscle and endothelial cells. We also suggest, for the first time, nNOS activity reduction by AM in non-neuronal cells.

Antidepressant Drugs Effects on Blood Pressure

Individuals suffering from depressive disorders display a greater incidence of hypertension compared with the general population, despite reports of the association between depression and hypotension. This phenomenon may depend, at least in part, on the use of antidepressant drugs, which may influence blood pressure through different effects on adrenergic and serotoninergic pathways, as well as on histaminergic, dopaminergic, and cholinergic systems. This review summarizes extant literature on the effect of antidepressant drugs on blood pressure. Selective serotonin reuptake inhibitors are characterized by limited effects on autonomic system activity and a lower impact on blood pressure. Thus, they represent the safest class—particularly among elderly and cardiovascular patients. Serotonin–norepinephrine reuptake inhibitors, particularly venlafaxine, carry a greater risk of hypertension, possibly related to greater effects on the sympathetic nervous system. The norepinephrine reuptake inhibitor reboxetine is considered a safe option because of its neutral effects on blood pressure in long-term studies, even if both hypotensive and hypertensive effects are reported. The dopamine–norepinephrine reuptake inhibitor bupropion can lead to blood pressure increases, usually at high doses, but may also cause orthostatic hypotension, especially in patients with cardiovascular diseases. The norepinephrine–serotonin modulators, mirtazapine and mianserin, have minimal effects on blood pressure but may rarely lead to orthostatic hypotension and falls. These adverse effects are also observed with the serotonin-reuptake modulators, nefazodone and trazodone, but seldomly with vortioxetine and vilazodone. Agomelatine, the only melatonergic antidepressant drug, may also have limited effects on blood pressure. Tricyclic antidepressants have been associated with increases in blood pressure, as well as orthostatic hypotension, particularly imipramine. Oral monoamine–oxidase inhibitors, less frequently skin patch formulations, have been associated with orthostatic hypotension or, conversely, with hypertensive crisis due to ingestion of tyramine-containing food (i.e., cheese reaction). Lastly, a hypertensive crisis may complicate antidepressant treatment as a part of the serotonin syndrome, also including neuromuscular, cognitive, and autonomic dysfunctions. Clinicians treating depressive patients should carefully consider their blood pressure status and cardiovascular comorbidities because of the effects of antidepressant drugs on blood pressure profiles and potential interactions with antihypertensive treatments.

Iatrogenic hypertension: a bioinformatic analysis

It is well known that a myriad of medications and substances can induce side effects that are related to blood pressure (BP) regulation. This study aims to investigate why certain drugs tend to cause iatrogenic hypertension (HTN) and focus on drug targets that are implicated in these conditions.Databases and resources such as SIDER, DrugBank, and Genomatix were utilized in order to bioinformatically investigate HTN-associated drug target-genes for which HTN is a side effect. A tree-like map was created, representing interactions between 198 human genes that relate to the blood pressure system. 72 HTN indicated drugs and 160 HTN-inducing drugs were investigated. HTN-associated genes affected by these drugs were identified. HTN indicated drugs, which target nearly all branches of the interaction tree, were shown to exert an effect on most functional sub-systems of the BP regulatory system; and specifically, for the adrenergic and dopaminergic receptor pathways. High prevalence (25 genes) of shared targets between the HTN indicated and HTN-inducing drug categories was demonstrated. We focus on six drug families which are not indicated for HTN treatment, yet are reported as a major cause for blood pressure side effects. We show the molecular mechanisms that may lead to this iatrogenic effect. Such an analysis may have clinical implications that could allow for the development of tailored medicine with fewer side effects.

Amitriptyline-induced ventricular tachycardia: a case report

Background

In Bangladesh, each emergency physician faces amitriptyline overdose nearly a day. An acute cardiovascular complication, one of the worst complications is mainly responsible for the mortality in tricyclic overdose. Recently, we managed ventricular tachycardia in a young female presented with an impaired consciousness 10 h after intentionally ingesting 2500 mg amitriptyline. Here, we report it, discuss how the electrocardiography is vital to acknowledge and predict it and its’ complications and also the recent update of the management of it.

Case presentation

A young married Bangladeshi-Bengali girl, 25-year-old, having a history of disharmony with her husband, came with an impaired consciousness after intentionally ingesting 2500 mg amitriptyline about 10 h before arrival. There was blood pressure 140/80 mmHg, heart rate 140 beats-per-min, temperature 103 °F, Glasgow coma scale 10/15, wide complex tachycardia with QRS duration of 178 ms in electrocardiography, blood pH 7.36. Initially, treated with 100 ml 8.4% sodium bicarbonate. After that, QRS duration came to 100 ms in electrocardiography within 10 min of infusion. To maintain the pH 7.50–7.55 over the next 24 h, the infusion of 8.4% sodium bicarbonate consisting of 125 ml dissolved in 375 ml normal saline was started and titrated according to the arterial blood gas analysis. Hence, a total dose of 600 mmol sodium bicarbonate was given over next 24 h. In addition to this, gave a 500 ml intravenous lipid emulsion over 2 h after 24 h of admission as she did not regain her consciousness completely. Afterward, she became conscious, though, in electrocardiography, ST/T wave abnormality persisted. So that, we tapered sodium bicarbonate infusion slowly and stopped it later. At the time of discharge, she was by heart rate 124/min, QRS duration 90 ms in electrocardiogram along with other normal vital signs.

Conclusion

Diagnosis of amitriptyline-induced ventricular tachycardia is difficult when there is no history of an overdose obtained. Nevertheless, it should be performed in the clinical background and classic electrocardiographic changes and wise utilization of sodium bicarbonate, intravenous lipid emulsion, and anti-arrhythmic drugs may save a life.

Cyclic Antidepressant Poisoning: A Review and Case Report

Although newer cyclic antidepressants have been introduced over the past several years, the tricyclic antidepressants (TCAs) continue to be the leading cause of morbidity from drug overdose in the United States. Overdose features depend on the particular cyclic antidepressant ingested and its pharmacological properties, and can include CNS depression, cardiac arrhythmias, hypotension, seizures, and anticholinergic symptomatology. Life-threatening symptomatology almost always begins within 2 hours, and certainly within 6 hours, after arrival to the emergency department. Plasma TCA levels are unreliable predictors of TCA toxicity and are not recommended. An ECG with a prolonged QRS complex more than 100 msec seems to be the best indicator of serious sequelae with TCAs. Management consists of stabilization of vital signs, gastrointestinal decontamination, intravenous sodium bicarbonate, and supportive care. Agents once thought to be useful for the treatment of cardiac dysrhythmias and seizures such as phenytoin and physostigmine should be avoided. The future of TCA antibody fragments in the treatment of TCA overdose seems promising. Newer and, to some degree, safer antidepressants in overdose have recently been introduced, and they include fluoxetine, trazodone, and sertraline. Amoxapine, bupropion, and maprotiline seem to be as toxic as the TCAs. A significant interaction between cyclic antidepressants and monoamine-oxidase inhibitors exists. Management includes supportive care and basic poison management. Prevention of poisoning seems to be the most logical and effective method of maintaining patient safety. TCAs should be avoided in children younger than 6 years old. All adults with suicidal ideations should receive no more than a 1-week supply (about 1 g) of drug. Finally consideration should be given to using one of the newer, safer antidepressants in all patients with suicidal ideations.

Intravenous lipid emulsion therapy does not improve hypotension compared to sodium bicarbonate for tricyclic antidepressant toxicity: a randomized, controlled pilot study in a swine model

OBJECTIVES

Tricyclic antidepressants (TCAs) are highly lipophilic medications used to treat posttraumatic stress disorder and chronic pain. Intravenous lipid emulsion (ILE) is a recent antidote for lipophilic drug overdose with unclear effectiveness. ILE has been studied in TCA overdose in small animals, and cases are reported in humans, but controlled studies in a larger animal model are lacking. Given the high lipophilicity of amitriptyline, a TCA, the hypothesis was that ILE would be more effective than the standard antidote sodium bicarbonate in improving amitriptyline-induced hypotension. The objective was to determine if ILE improved hypotension (defined by a mean arterial pressure [MAP] < 60% baseline) compared to sodium bicarbonate for amitriptyline overdose in a critically ill porcine model.

METHODS

In this prospective, randomized, controlled trial, 24 female Sus scrofa swine weighing 45 to 55 kg were infused with amitriptyline at 0.5 mg/kg/min until the MAP reached 60% of baseline values. Animals were randomized to the experimental treatment group (ILE 7 mL/kg bolus, then 0.25 mL/kg/min) or the standard treatment group (sodium bicarbonate 2 mEq/kg plus an equal volume of saline). The primary outcome was a 50% improvement in MAP after ILE administration. We continuously monitored heart rate (HR), systolic blood pressure (sBP), MAP, and cardiac output. Electrocardiograms were recorded every 15 minutes. Serum pH, pCO2 , bicarbonate, lactate, and electrolytes were measured. Amitriptyline levels were measured by liquid chromatography/tandem mass spectrometry. Statistical methods used to detect a difference in MAP between the two treatment groups included repeated-measures analysis of variance, adjusted for treatment, time, and the interaction of treatment by time. A sample size of 12 animals per group provided a power of 0.8 and an alpha of 0.05 to detect a 50% difference in MAP.

RESULTS

There was no difference at baseline between ILE and sodium bicarbonate groups in mean HR, sBP, MAP, or cardiac output. Mean amounts of amitriptyline to reach hypotension and time to hypotension were similar between groups. After hypotension there was no difference between groups for mean HR, sBP, MAP, or cardiac output. The median time from hypotension to death was greater for the sodium bicarbonate group (10 minutes [IQR = 6 to 61 minutes] vs. 5 minutes [IQR = 4.5 to 6 minutes] for the ILE group; p = 0.003), but overall survival was not different. One ILE and four sodium bicarbonate pigs survived. Additionally, no difference was detected in QRS intervals between the two groups. The mean (±SD) amitriptyline level in the lipid layer was 3.34 (±2.12) μg/mL, and in the aqueous layer, 4.69 (±2.44) μg/mL. The ILE fatty layer contained 38.2% of total measurable amitriptyline, while the aqueous layer contained 53.6%.

CONCLUSIONS

Intravenous lipid emulsion treatment failed to improve amitriptyline-induced hypotension when compared to the standard treatment of sodium bicarbonate in a large animal model of severe TCA overdose. Larger groups with better survival may yield different results from the high mortality observed in this pilot study. Similar amounts of amitriptyline were found in the aqueous and lipid layers. These conclusions are limited to a single ILE regimen.

Terlipressin as an adjunct vasopressor in refractory hypotension after tricyclic antidepressant intoxication

AIM OF STUDY

To report the management of cardiovascular failure refractory to standard catecholamine therapy with terlipressin in a patient with tricyclic antidepressant (TCA) intoxication.

CASE REPORT

A 41-year-old woman, with suicidal ingestion of 11.25 g amitriptyline and 1500 mg diclofenac, was admitted to the emergency department. After 30 min in ventricular fibrillation, with ongoing CPR, she regained a potentially perfusing rhythm, but with hypotension refractory to standard catecholamine therapy with adrenaline, 2 microg/kg/min (norepinephrine); adrenaline, 1 microg/kg/min (epinephrine) until 55 min after admission. An injection of 1 mg terlipressin restored mean arterial blood pressure >65 mmHg within 10 min. Ten hours after admission to the intensive care unit, catecholamine support could be withdrawn because of a stable haemodynamic state. Within 7 days, all organ function recovered, and the patient regained full neurological function.

CONCLUSIONS

Successful management of cardiovascular failure with terlipressin after TCA intoxication refractory to catecholamines suggests a potential role for terlipressin as an adjunct vasopressor in severely hypotensive patients.

Acute Myocardial Infarction Associated with Amitriptyline Overdose

Tricyclic antidepressant overdose is known to cause cardiopulmonary and central nervous system complications. As with other cardiovascular complications, amitriptyline toxicity may cause acute myocardial infarction. This paper reports the case of a young female with acute myocardial infarction as a novel consequence of tricyclic antidepressant overdose.

Tricyclic antidepressant poisoning : cardiovascular toxicity

Tricyclic antidepressants remain a common cause of fatal drug poisoning as a result of their cardiovascular toxicity manifested by ECG abnormalities, arrhythmias and hypotension. Dosulepin and amitriptyline appear to be particularly toxic in overdose. The principal mechanism of toxicity is cardiac sodium channel blockade, which increases the duration of the cardiac action potential and refractory period and delays atrioventricular conduction. Electrocardiographic changes include prolongation of the PR, QRS and QT intervals, nonspecific ST segment and T wave changes, atrioventricular block, right axis deviation of the terminal 40 ms vector of the QRS complex in the frontal plane (T 40 ms axis) and the Brugada pattern (downsloping ST segment elevation in leads V1-V3 in association with right bundle branch block). Maximal changes in the QRS duration and the T 40 ms axis are usually present within 12 hours of ingestion but may take up to a week to resolve. Sinus tachycardia is the most common arrhythmia due to anticholinergic activity and inhibition of norepinephrine uptake by tricyclic antidepressants but bradyarrhythmias (due to atrioventricular block) and tachyarrhythmias (supraventricular and ventricular) may occur. Torsade de pointes occurs uncommonly. Hypotension results from a combination of reduced myocardial contractility and reduced systemic vascular resistance due to alpha-adrenergic blockade. Life-threatening arrhythmias and death due to tricyclic antidepressant poisoning usually occurs within 24 hours of ingestion. Rapid deterioration is common. Level of consciousness at presentation is the most sensitive clinical predictor of serious complications. Although a QRS duration >100 ms and a rightward T 40 ms axis appear to be better predictors of cardiovascular toxicity than the plasma tricyclic drug concentration, they have at best moderate sensitivity and specificity for predicting complications.

Acute poisoning: understanding 90% of cases in a nutshell

The acutely poisoned patient remains a common problem facing doctors working in acute medicine in the United Kingdom and worldwide. This review examines the initial management of the acutely poisoned patient. Aspects of general management are reviewed including immediate interventions, investigations, gastrointestinal decontamination techniques, use of antidotes, methods to increase poison elimination, and psychological assessment. More common and serious poisonings caused by paracetamol, salicylates, opioids, tricyclic antidepressants, selective serotonin reuptake inhibitors, benzodiazepines, non-steroidal anti-inflammatory drugs, and cocaine are discussed in detail. Specific aspects of common paediatric poisonings are reviewed.

[Hypotensive cardio-circulatory failure and metabolic acidosis after suicidal intoxication with trimipramine and quetiapine. Case report and background]

The case of a 44-year-old female patient is reported, who ingested trimipramine and quetiapine in a suicide attempt. Initially sinus tachycardia and hypotension were seen, which resulted in a hypotensive cardio-circulatory failure despite fluid therapy and administration of catecholamines. Because of the life-threatening situation and the fact that the ingestion was 2 h prior to admission, a rapid transport to the next hospital was preferred to treatment with active charcoal. Intoxication with tricyclic antidepressants are very common in Europe and have a mortality of up to 15% in severe cases. The specific therapy consists of airway management, hemodynamic stabilization and primary elimination of the poison. Secondary detoxication is less important. The administration of the antidote physostigmine is controversial but carbo medicinalis should be given orally or via a gastric tube.

Tricyclic antidepressant overdose: a review

Overdoses of tricyclic antidepressants are among the commonest causes of drug poisoning seen in accident and emergency departments. This review discusses the pharmacokinetics, clinical presentation and treatment of tricyclic overdose.

Plasma alkalinization for tricyclic antidepressant toxicity: a systematic review

OBJECTIVE

To review the evidence that plasma alkalinization improves the outcome in tricyclic antidepressant toxicity.

METHODS

Medline search from 1966 to October 2000 (articles in all languages were included) and examination of bibliographies. Published papers including animal studies, in vitro studies, human case reports, case series and retrospective studies were reviewed.

RESULTS

Our search identified 115 publications, all of which were retrieved. Human studies included eight case reports, four case series, one controlled study and two retrospective chart reviews. No randomized controlled human trials were found. Twelve animal studies were identified that investigated pH manipulation or saline load and their effects on physiological parameters in tricyclic antidepressant toxicity.

CONCLUSIONS

The practice of alkalinization for tricyclic antidepressant toxicity is based on animal studies, case reports and opinion. The mechanism of action appears to be multifaceted and may vary between different tricyclic antidepressants. Significant interspecies variation makes extrapolation from animal studies to humans difficult. Alkalinization therapy appears reasonable in patients with compromising dysrhythmias and shock when supportive interventions have been ineffective; however, the available evidence does not support prophylactic alkalinization in the absence of life-threatening cardiovascular toxicity.

Antidepressant Poisoning and Treatment: A Review and Case Illustration

Although newer antidepressants have been introduced over the past several years, the tricyclic antidepressants (TCAs) continue to be a leading cause of morbidity from drug overdose in the United States. Overdose features depend on the particular cyclic antidepressant ingested and its pharmacological properties, and can include CNS depression, cardiac dysrhythmias, hypotension, seizures, and anticholinergic symptoms. Life-threatening events almost always begin within two hours, and certainly within six hours, after arrival to the emergency department. Plasma TCA levels are unreliable predictors of TCA toxicity and are therefore not recommended. An ECG with a prolonged QRS complex more than 100 msec seems to be the best indicator of serious sequelae with TCA overdose. Management consists of stabilization of vital signs, gastrointestinal decontamination, intravenous sodium bicarbonate, and supportive care. Agents once thought to be useful for the treatment of cardiac dysrhythmias and seizures such as phenytoin and physostigmine should be avoided. The future of TCA antibody fragments in the treatment of TCA overdose seems promising. Amoxapine, bupropion, and maprotiline seems to be as toxic as the TCAs. Overdose data is limited for venlafaxine, and mirtazapine, and preclude firm conclusions. A significant interaction between cyclic antidepressants and monoamine-oxidase inhibitors exists. Management includes supportive care and basic poison management. Prevention of poisoning seems to be the most logical and effective method of maintaining patient safety. TCAs should be avoided in children younger than 6 years old. All adults with suicidal ideations should receive no more than a one-week supply (less than 1 g) of drug. Newer and, to some degree, safer antidepressants in overdose have recently been introduced, and they include fluoxetine, sertraline, paroxetine, trazodone, and nefazodone. Finally, consideration should be given to using one of these newer, safer antidepressants in all patients with suicidal ideations.

Dibenzepin overdose causing pulmonary edema

OBJECTIVE

To report a case of pulmonary edema due to dibenzepin overdose.

CASE SUMMARY

A 39-year-old woman was hospitalized 24 hours after she ingested eight tablets of dibenzepin hydrochloride delayed-release 240 mg/tablet (approximately 35 mg/kg body weight). On admission the patient was confused, and physical examination revealed sinus tachycardia (HR 130 beats/min). Forty-five hours after ingestion of the dibenzepin she developed pulmonary edema and was treated with furosemide, morphine, and mechanical ventilation through an endotracheal tube for 48 hours. Repeated echocardiography revealed left ventricular dysfunction that resolved as the medical condition of the patient improved. Appropriate studies excluded pneumonia, pneumonitis, adult respiratory distress syndrome, myocardial infarction, and pulmonary emboli as contributing factors to this patient's condition.

DISCUSSION

Tricyclic antidepressant overdose is known to cause cardiopulmonary complications, including pulmonary edema. To the best of our knowledge, this is the first reported case of pulmonary edema as a result of dibenzepin overdose. The most probable mechanism for this complication is depression of the left ventricular function.

CONCLUSIONS

As with other tricyclic antidepressants, dibenzepin toxicity may cause pulmonary edema. Close patient monitoring is essential for at least 48-72 hours after the overdose.

Identifying toxicity risk early after antidepressant overdose

Despite the risk of life-threatening toxicities, care of most patients after antidepressant overdose (ADO) does not require the use of critical care resources. The use of emergency department (ED) clinical findings to identify ADO patients who subsequently manifested toxicity was evaluated prospectively. ADO risk assessment (ADORA) criteria included development of QRS interval > 0.10 seconds, arrhythmias, altered mental status, seizures, respiratory depression, or hypotension. Sixty-seven ADO patients were identified on presentation to a single ED and classified as low risk (LR, absence of criteria) or high risk (HR, presence of one or more criteria) based on development of criteria within 6 hours of ingestion (or ED presentation if ingestion time was not established). This system demonstrated 100% sensitivity in identifying study patients who developed significant toxicity problems. None of the 28 LR patients and 13 of 39 HR patients had subsequent complications (P < .01). No single clinical finding permitted risk classification. ADORA should identify patients who do not require further monitoring or other aggressive medical management for ADO.

Diagnostic utility of flumazenil in coma with suspected poisoning: a double blind, randomised controlled study

OBJECTIVE

To assess the diagnostic value and safety of the benzodiazepine antagonist flumazenil in patients with coma of unclear origin with suspected poisoning.

DESIGN

Double blind, placebo controlled, randomised study.

SETTING

Intensive care unit at a major teaching hospital.

PATIENTS

105 Unconscious adults admitted consecutively with suspected drug overdosage during 18 months from a total of 362 cases of poisoning. Exclusion criteria were pregnancy, epilepsy, obvious poisoning with drugs identified unequivocally from information from relatives or others as other than benzodiazepines, and coma score greater than 10 on a scale graded from 4 to 20. Patients were allocated randomly to receive flumazenil (21 men and 32 women) or placebo (25 men and 27 women).

INTERVENTIONS

Intravenous injection of flumazenil (10 ml, 0.1 mg/ml) or placebo (10 ml vehicle alone) given double blind over three minutes.

MAIN OUTCOME MEASURES

Serum and urine concentrations of benzodiazepines, antidepressants, and several other agents; blood gas tensions; standardised evaluation on admission and five minutes after the injection by means of coma scale score and urgent diagnostic or therapeutic interventions indicated according to the history and clinical examination; standardised interview after the injection to try to ascertain further information; and adverse reactions.

RESULTS

Benzodiazepines were found in the serum in 36 of the 53 patients in the flumazenil group and in 37 of the 52 who received placebo. The average coma scale score increased significantly after injection in the flumazenil group (6.4 v 12.1, p less than 0.001) but not in the placebo group. In the flumazenil group several interventions were rendered unnecessary by the injection: gastric lavage and urinary catheterisation (19 patients each), intubation (21), artificial ventilation and computed tomography of the brain (three patients each), blood culture and lumbar puncture (one patient each), and electroencephalography (two). In the placebo group the indications for these procedures did not change in any patient after injection. The 95% confidence interval for the difference in reduction of the frequency of indications for gastric lavage after injection between the two groups was 21% to 51%, that for intubation 25% to 55%, and that for urinary catheterisation 21% to 51%. In the flumazenil group 21 patients gave valuable information on their drug ingestion within 10 minutes after injection compared with only one in the placebo group (p less than 0.001). Nine adverse reactions were recorded in the flumazenil group, eight of which were graded as mild and one severe. The safety of the antagonist was acceptable, even though 60% of the patients in the flumazenil group had multiple drug poisoning including benzodiazepine. No epileptic seizures or arrhythmias were recorded.

CONCLUSION

Flumazenil is a valuable and safe differential diagnostic tool in unclear cases of multiple drug poisoning.