Treatment of antidepressant poisoning with resin hemoperfusion

Extracorporeal treatment for tricyclic antidepressant poisoning: recommendations from the EXTRIP Workgroup

The Extracorporeal Treatments In Poisoning (EXTRIP) workgroup was formed to provide recommendations on the use of extracorporeal treatments (ECTR) in poisoning. Here, the workgroup presents its results for tricyclic antidepressants (TCAs). After an extensive literature search, using a predefined methodology, the subgroup responsible for this poison reviewed the articles, extracted the data, summarized findings, and proposed structured voting statements following a predetermined format. A two-round modified Delphi method was chosen to reach a consensus on voting statements and RAND/UCLA Appropriateness Method to quantify disagreement. Blinded votes were compiled, returned, and discussed in person at a meeting. A second vote determined the final recommendations. Seventy-seven articles met inclusion criteria. Only case reports, case series, and one poor-quality observational study were identified yielding a very low quality of evidence for all recommendations. Data on 108 patients, including 12 fatalities, were abstracted. The workgroup concluded that TCAs are not dialyzable and made the following recommendation: ECTR is not recommended in severe TCA poisoning (1D). The workgroup considers that poisoned patients with TCAs are not likely to have a clinical benefit from extracorporeal removal and recommends it NOT to be used in TCA poisoning.

Temporary cardiac pacemaker in the treatment of junctional rhythm and hypotension due to imipramine intoxication

Tricyclic antidepressants (TCAs) account for approximately 3% of all pediatric hospitalizations due to poisoning. TCAs remain a common cause of fatal drug poisoning because of their cardiovascular toxicity as manifested by electrocardiogram (ECG) abnormalities, arrhythmias, and hypotension. We report a 15-year-old girl with junctional escape rhythm and resistant hypotension caused by severe imipramine intoxication. Initial ECG showed junctional escape rhythm (46 bpm) with no atrial activity, low QRS voltage, widening of the QRS complex (160 ms) with a right bundle branch-like pattern, R wave > 3 mm in aVR (6 mm), and prolongation of the QT interval (QTc 550 ms). Despite intravenous fluids and inotropic support, she had resistant hypotension and acute renal failure. Junctional rhythm was successfully terminated by using temporary cardiac pacemaker. Hemodialysis and hemoperfusion were also performed. She was discharged on the day 5 without any complications. During follow-up, no ECG abnormalities were noted. We reported successful use of temporary cardiac pacemaker for treatment of junctional rhythm and resistant hypotension in imipramine intoxication. The conventional methods of activated charcoal, alkalinization, and symptomatic treatment of complications are usually enough for nonlethal doses of TCA intoxication. However, in imipramine intoxication with serious arrythmias and hypotension, using temporary cardiac pacemaker, hemodialysis, and hemoperfusion can be a life-saving therapeutic approach.

The Management of Tricyclic Antidepressant Poisoning

Although there have been descriptive, uncontrolled clinical reports of removal of tablet debris by gastric lavage, there have been no clinical studies that have demonstrated that this has any impact on outcome in patients with tricyclic antidepressant (TCA) poisoning. There is also the possibility that lavage may increase drug absorption by pushing tablets into the small intestine. Furthermore, gastric lavage in patients with TCA poisoning may induce hypoxia and a tachycardia potentially increasing the risk of severe complications such as arrhythmias and convulsions. In view of the paucity of evidence that gastric lavage removes a significant amount of drug and the risk of complications associated with the procedure, the routine use of gastric lavage in the management of patients with TCA poisoning is not appropriate. Volunteer studies have shown generally that activated charcoal is more likely to reduce drug absorption if it is administered within 1 hour of drug ingestion. In the one volunteer study that looked at later administration of activated charcoal, there was a 37% decrease in plasma concentration associated with administration of activated charcoal at 2 hours post-ingestion. There have been no clinical studies that enable an estimate of the effect of activated charcoal administration on outcome in the management of patients with TCA poisoning. Volunteer studies have shown that multiple-dose activated charcoal increases the elimination of therapeutic doses of amitriptyline and nortriptyline, but not of doxepin or imipramine; however, these studies cannot be directly extrapolated to the management of patients with TCA poisoning. There have been no well designed controlled studies that have assessed the impact of multiple-dose activated charcoal in the management of patients with TCA poisoning. Because of the large volume of distribution of TCAs, it would not be expected that their elimination would be significantly increased by multiple-dose activated charcoal.Haemoperfusion, haemodialysis and the combination of these procedures do not result in significant removal of TCAs and are not recommended in the management of patients with TCA poisoning.

Hemoperfusion in a child with amitriptyline intoxication

Tricyclic antidepressant overdose is one of the most common causes of serious drug poisoning in children and adults. We report a 17-month-old girl with severe amitriptyline intoxication. She was admitted to hospital because of lethargy and seizures. It was estimated that she took approximately 75 mg/kg of amitriptyline 2 h before admission. On examination she was comatose, had ventricular tachycardia and multifocal clonic seizures. Intravenous fluid, per oral activated charcoal, diazepam, lidocaine, and sodium bicarbonate infusion were given. However, there was no response to this therapy, and the patient remained in a deep coma with cardiac arrhythmias and seizures. Hemoperfusion (HP) was performed for 2 h. During this procedure, cardioversion was used six times due to ventricular fibrillation. She had a very good clinical response to HP and no complication was observed. We suggest that HP may be an effective treatment in children with severe amitriptyline intoxication.

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.

Modelling of non-linear pharmacokinetics in sheep after short-term infusion of cardiotoxic doses of imipramine

Imipramine was administered to sheep (n = 10) by intravenous infusion in high doses (450 mg-900 mg) to elicit cardiovascular shock. A cardiac assist device was then employed to manage the acute overdose situation. The concentration-time course of imipramine and its metabolite desmethylimipramine in plasma was measured by HPLC. As an indicator of imipramine's cardiotoxic effect, cardiac output was monitored. The aim of the study was to evaluate the pharmacokinetics under these conditions and to assess the efficiency of a cardiac assist device with (n = 5) and without (n = 5) an integrated haemoperfusion unit in removing drug from the circulation. The kinetics of imipramine could be described by a three compartment body model with concentration-dependent clearance resulting in non-linear kinetics. The changes in cardiac output with time could be linked to the pharmacokinetic model by a linear relationship. The cardiac assist device was found to contribute to the overall elimination of imipramine whereas the haemoperfusion unit had no clinically relevant impact.

Cyclic antidepressant overdose: a review of current management strategies

Cyclic antidepressant (CA) overdose can produce life-threatening seizures, hypotension, and dysrhythmias. It accounts for up to half of all overdose-related adult intensive care unit admissions and is the leading cause of death from drug overdose in patients arriving at the emergency department alive. Several factors contribute to the significant morbidity and mortality associated with CA overdose. First, CAs are widely prescribed and are dispensed to patients at increased risk for attempting suicide. Second, drugs of this class generally have a low therapeutic toxic ratio. Third, in the majority of fatal cases, the patient dies before reaching a hospital. Finally, and of greatest significance for the clinician, the presenting signs and symptoms of CA overdose may be missed by the physician, even in cases of severe toxicity. Therefore, CAs must be considered early in any case of suspected overdose, and all such cases should be managed as potentially fatal ones. The following case demonstrates the current approach to the patient with significant CA toxicity.

Pretreatment with drug-specific antibody reduces desipramine cardiotoxicity in rats

The effect of a drug-specific antibody on desipramine (DMI) cardiotoxicity was studied in rats. Animals were pretreated i.v. with 4.2 g/kg of a monoclonal antibody (anti-TCA) followed by DMI HCl 30 mg/kg i.p. (molar ratio of anti-TCA binding sites to DMI = 0.56). Peak QRS complex prolongation was substantially lower after pretreatment with anti-TCA than after control antibody (70 +/- 14 v. 21 +/- 4%, p less than 0.001). Time to peak toxicity was the same in both groups. Binding of DMI by anti-TCA was demonstrated by a higher serum total DMI concentration and increased DMI binding in serum after anti-TCA compared to controls. The DMI concentration in anti-TCA treated animals was lower in some organs (brain, lung, liver, spleen), but not in others (heart, muscle, kidney, fat). The calculated fraction of the DMI dose bound by anti-TCA was 19.9%. The steepness of the DMI dose-response curve was examined by administering DMI alone (without antibody) at various doses to rats. Compared to 30 mg/kg DMI, a dose reduction of 30-50% was needed to reduce QRS duration to the same extent as anti-TCA pretreatment. We conclude that DMI cardiotoxicity was markedly reduced by the binding of a relative small fraction of the DMI body burden to anti-TCA. This disproportionate effect of DMI binding was not due to the steepness of the DMI dose-response curve, nor to slowing of the rate of DMI distribution to tissues.

The effect of a lipid suspension on amitriptyline disposition

A 5-h infusion of a lipid suspension or saline was given on separate occasions to four healthy volunteers taking amitriptyline. Mean plasma levels of amitriptyline plus nortriptyline were 14% higher at the end of the lipid infusion but the difference was not statistically significant. Infusion of a lipid suspension is unlikely to materially affect the severity of amitriptyline intoxication.

Poisoning due to tricyclic antidepressant overdosage. Clinical presentation and treatment

Tricyclic antidepressants are among the commonest causes of both non-fatal and fatal drug poisoning in the world. Their toxicity is due to effects on the brain, the heart, the respiratory system and the parasympathetic nervous system. Symptoms usually appear within 4 hours of an overdose and all but the most seriously poisoned patients recover within 24 hours. The most common clinical features are dry mouth, blurred vision, dilated pupils, sinus tachycardia, pyramidal neurological signs, and drowsiness. In severe poisoning, there may be coma, convulsions, respiratory depression, hypotension and a wide range of electrocardiographic (ECG) abnormalities. The most frequent findings on the ECG are prolongation of the PR and QT intervals; the tracing may resemble bundle branch block or supraventricular or ventricular tachycardias. Treatment of poisoning due to the tricyclic antidepressants is essentially supportive, there being insufficient evidence at present to recommend the use of methods to increase elimination of the drug from the body. Gastric aspiration and lavage should be performed if more than 750 mg of drug have been taken. There must be regular monitoring for hypoxia, acidosis and hypokalaemia and these complications should be corrected enthusiastically. Convulsions should be treated with diazepam or chlormethiazole. Muscular paralysis and artificial ventilation should be employed if anticonvulsants are ineffective. Hypotension should be treated firstly by fluid replacement and then with sympathomimetic agents (dopamine or dobutamine). Antiarrhythmic drugs should only be employed if there is evidence of circulatory failure which fails to respond to correction of hypotension. Sodium bicarbonate infusions should be given to cardiotoxic patients who are acidotic and are worth trying even if the patient is not acidotic. Although physostigmine salicylate will reverse most of the features of tricyclic antidepressant poisoning, its effects are short-lived in serious toxicity and it can produce dangerous side effects; physostigmine should therefore be reserved for those patients who have complications of coma or who have resistant cardiotoxicity or convulsions. Drug screening and quantitative determination of tricyclic antidepressant serum concentrations are useful in a minority of patients who have severe, unusual or prolonged symptoms.

Tricyclic antidepressant poisoning. Management of arrhythmias

Deaths from tricyclic antidepressant (TCA) overdose are usually due to arrhythmias and/or hypotension. Tricyclic antidepressant toxicity is due mainly to the quinidine-like actions of these drugs on cardiac tissues. Slowing of phase 0 depolarisation of the action potential results in slowing of conduction through the His-Purkinje system and myocardium. Slowed impulse conduction is responsible for QRS prolongation and atrioventricular block, and contributes to ventricular arrhythmias and hypotension. Therapies that improve conduction, e.g. hypertonic sodium bicarbonate, are useful in treating these toxic effects. Other mechanisms contributing to arrhythmias include abnormal repolarisation, impaired automaticity, cholinergic blockade and inhibition of neuronal catecholamine uptake. Toxicity may be worsened by acidaemia, hypotension or hyperthermia. Sinus tachycardia is due to the anticholinergic effects of the tricyclic antidepressants as well as blockade of neuronal catecholamine reuptake. Sinus tachycardia is generally well-tolerated and requires no therapy. Sinus tachycardia with QRS prolongation may be difficult to distinguish from ventricular tachycardia. Electrocardiograms obtained using oesophageal or atrial electrodes may be useful in determining the relationship of atrial and ventricular activity. Although QRS prolongation alone is not compromising, it is a marker for patients at highest risk of developing seizures, arrhythmias or hypotension. Ventricular tachycardia (monomorphic) is a consequence of impaired myocardial depolarisation and impulse conduction. Hypertonic sodium bicarbonate may partially correct impaired conduction and be of benefit in treating ventricular tachycardia. Since hypertonic sodium bicarbonate appears to act by increasing the extracellular sodium concentration as well as by increasing extracellular pH, hyperventilation may be less effective. Hypertonic sodium bicarbonate is of particular benefit in patients who are acidotic, since acidosis aggravates cardiac toxicity. However, administration of hypertonic sodium bicarbonate is beneficial even when blood pH is normal. Lignocaine (lidocaine) may be useful in treating ventricular tachycardia but should be administered cautiously to avoid precipitating seizures. Ventricular bradyarrhythmias are due to impaired automaticity or depressed atrioventricular conduction and can be treated by placement of a temporary pacemaker, or with a chronotropic agent, e.g. isoprenaline (isoproterenol), with or without concomitant vasoconstrictors.(ABSTRACT TRUNCATED AT 400 WORDS)

Haemoperfusion: a useful therapy for a severely poisoned patient?

Although it is many years since a haemodialysis and haemoperfusion over uncoated and later coated charcoal columns have been used for the treatment of intoxicated patients, the clinical efficacy of these extracorporeal techniques in the treatment of severely poisoned patients remains a matter of debate. Some of the reasons for this controversy may be the indiscriminate use of haemoperfusion in any form of intoxication, the lack of well-controlled studies and the wrong interpretation of the high haemoperfusion clearance values sometimes obtained. Simple pharmacokinetic principles are applied to this type of treatment and some practical guidelines as to how and when haemoperfusion should be applied or presented are reviewed. The limited place of haemoperfusion in the treatment of severe poisoning, its further declining use in the future, at least in its present design, and some promising new treatments are emphasized.

Predicative calculation of the efficiency of hemodialysis or hemoperfusion for the removal of drugs from the body

Formula are derived for the calculation of the amounts of drug which, during a defined time interval, are eliminated from the body with and without the help of hemodialysis or hemoperfusion (HD/HP). A programmable pocket calculator like the TI-59 suffices to perform all calculations. The pharmacokinetic system constants of the drug, the effective plasma flow, and the HD/HP plasma extraction rate are entered into the program. Additional information can be obtained if the plasma concentration of the drug at the onset of HD/HP is known. Worked examples are presented.

Resin haemoperfusion in levomepromazine poisoning: evaluation of effect on plasma drug and metabolite levels

Plasma levels of levomepromazine and two of its major metabolites N-desmethyl-levomepromazine and levomepromazine sulphoxide were studied in two poisoned patients treated with resin haemoperfusion at a constant blood flow of 200 ml/min. The mean haemoperfusion clearance of levomepromazine, N-desmethyl-levomepromazine and levomepromazine sulphoxide was 114, 123 and 151 ml/min, respectively, in patient no. 1, and 153, 148 and 184 ml/min, respectively, in patient no. 2. Patient no. 2 had also ingested amitriptyline, and the mean haemoperfusion clearance of amitriptyline and its metabolite nortriptyline was 183 and 183 ml/min respectively. Haemoperfusion did not seem to alter the elimination profile of levomepromazine or the two metabolites in either patient. We conclude that haemoperfusion is of little value in removing levomepromazine, N-desmethyl-levomepromazine or levomepromazine sulphoxide from the body. This is probably due to the large apparent volume of distribution and the high intrinsic hepatic metabolic clearance of these compounds.

Inotropic effect of prenalterol in amitriptyline poisoning

A case of severe amitriptyline poisoning with grade IV coma, seizures, bradycardia and hypotension who did not respond to dopamine was successfully treated with prenalterol, a new cardioselective beta-agonist. The case is discussed with respect to plasma concentrations of dopamine, prenalterol and amitriptyline. Prenalterol, hydrocortisone and insulin may be useful as inotropic agents in tricyclic poisoning where dopamine fails to provide an adequate response.

Lidocaine and amitriptyline interaction during experimental haemoperfusion

Displacement of amitriptyline by lidocaine was studied during haemoperfusion (HP) in five beagle dogs. Clearance of amitriptyline during HP was 0.93, although the amount of amitriptyline removed was only 2% of the given dose. Lidocaine does therefore not improve amitriptyline yield during HP. Clearance of lidocaine during HP was 0.99. Almost 13% of the lidocaine given intravenously was removed by HP. Lidocaine did not improve myocardial performance during HP in amitriptyline-intoxicated dogs. At necropsy the highest concentrations of amitriptyline in this model were found in the brain and the lung. The amitriptyline/nortriptyline ratio was lowest in the liver and lung, suggesting that these two organs are major sites of metabolism.

Clinical course in acute self-poisonings: a prospective study of 1125 consecutively hospitalised adults

The clinical course in an unselected group of 1125 consecutively hospitalised self-poisonings was studied during 1 year in Oslo. Mortality was 0.5%, but only 0.3% in those admitted without cardiac and respiratory arrest. Mortality among those in grade IV coma was 4.2%. The deepest comas (grade III or IV) occurred in 25.1% of the admissions with a mean duration of the coma of 5.8 h (range 1-80). Complications occurred in 21.7% of the admissions and 6.9% suffered more than one complication of which the most frequent were respiratory depression (13.5%), hypotension (5.3%), pneumonia (4.4%), and hypothermia (1.6%). The complication rate was highest in poisonings with opiates (60.7%), meprobamate (37.5%) and antihistamines (30.0%). Arrhythmias and respiratory depression were closely associated with poisonings with antidepressants and opiates, respectively. Owing to frequent polydrug overdoses it was difficult to associate other complications with other main toxic agents. Administration of antidotes (20.6%), cuffed intubation (4.4%) and forced alkaline diuresis (3.4%) were the most frequent special therapeutic measures taken. The change in pattern of self-poisonings in Oslo focuses on antidote therapy and intensive care, especially outside hospital, but limits the need for haemodialysis and haemoperfusion which were performed in only 1.0% of the admissions.

Effects of self poisoning with maprotiline

Self poisoning with maprotiline was studied in 41 patients (43 episodes) consecutively admitted to an intensive care unit. Thirty five patients had taken more than one drug or alcohol. Fifteen patients were in coma grade III or IV; 17 patients were still not conscious after 24 hours in the intensive care unit. Among six patients given ventilation the mean duration of ventilation in the five who recovered was 36 hours. Three patients had a cardiorespiratory arrest, and one patient died. Twenty eight patients had a QRS interval of 100 ms or more, and 15 patients had seizures. In six patients seizures were precipitated by physostigmine. Cardiotoxicity after overdosage of maprotiline is equal to if not greater than that found after overdosage of conventional tricyclic antidepressants. Overdosage of maprotiline is more often associated with seizures than overdosage with tricyclic antidepressants. Physostigmine further increases the risk of seizures and should not be used in cases of overdosage of maprotiline.

Resin hemoperfusion in chloroquine poisoning

A 46-year-old woman was admitted after ingestion of 10 g chloroquine phosphate. The patient's clinical condition deteriorated with characteristic ECG changes, low blood pressure, and respiratory depression. Resin hemoperfusion (HP) was started 4.5 h after admission at a flow of 250 mL/min for 4 h. Clearance over the resin column was 136 mL/min. Although the patient rapidly improved, a total of no more than 200 mg (2%) was removed. Total body clearance of chloroquine was increased by only 5% during HP. Treatment should therefore be directed toward aggressive supportive therapy rather than techniques to increase elimination.