A Meta‐Analysis of Prognostic Indicators to Predict Seizures, Arrhythmias or Death After Tricyclic Antidepressant Overdose

OBJECTIVES

To systematically review and summarize studies on the accuracy of ECG and tricyclic antidepressant (TCA) concentration as prognostic indicators of the risk of seizures, ventricular arrhythmia (VA) or death in patients with TCA overdose.

METHODS

Articles were identified with MedLine and Cochrane register of controlled clinical trials searches and review of medical toxicology textbooks. Quality of the included studies was assessed. Pooled estimates of sensitivity, specificity, likelihood ratios and Summary Receiver Operating Characteristics (SROC) curves were generated.

RESULTS

A total of 18 studies were included in the analysis. The pooled sensitivity (Se) and specificity (Sp) of the QRS for predicting seizures were 0.69 [95% CI 0.57-0.78] and 0.69 [95% CI 0.58-0.78] as compared to 0.75 [95% CI 0.61-0.85] and 0.72 [95% CI 0.61-0.81] for the TCA concentration. The Se and Sp of the QRS to predict VA were 0.79 [95% CI 0.58-0.91] and 0.46 [95% CI 0.35-0.59] compared to 0.78 [95% CI 0.56-0.90] and 0.57 [95% CI 0.46-0.67] for the TCA concentration. The Se and Sp of the QRS to predict death were 0.81 [95% CI 0.54-0.94] and 0.62 [95% CI 0.55-0.68] compared to 0.76 [95% CI 0.49-0.91] and 0.60 [95% CI 0.47-0.72] for the TCA concentration. Very few studies evaluated the accuracy of QTc, T 40 ms axis and the R/S ratio.

CONCLUSIONS

Overall, the studies suggested that the ECG and TCA concentration have similar but relatively poor performance for predicting complications, such as seizures, VA or death, associated with TCA overdose.

Two Cases Involving Clomipramine Intoxication

Clomipramine and its active metabolite norclomipramine were identified and quantitated in multiple tissues recovered from two postmortem cases using liquid chromatography-mass spectrometry. In both cases clomipramine toxicity was assessed primarily upon levels determined from brain samples. This communication supplements the database on clomipramine and norclomipramine by providing quantitative determinations of both parent drug and metabolite in multiple tissues. A literature search revealed a paucity of data on clomipramine and norclomipramine levels in general and a total absence of documented brain levels. In patients who have undergone long-term tricyclic antidepressant (TCA) therapy, blood and liver analysis alone may not be sufficient to establish toxicity. Such patients can sequester substantial amounts in liver, a concern because the TCAs are subject to significant postmortem redistribution. When conducting postmortem investigations, the inclusion of brain determination provides valuable information in assessing the magnitude of toxicity in cases involving clomipramine and its active metabolite norclomipramine.

Medications that can be fatal for a toddler with one tablet or teaspoonful: a 2004 update

OBJECTIVE

To provide an updated list of the highly toxic medications in North America that can kill a 10 kg toddler upon ingestion of 1-2 dose units.

METHODS

All drugs available in North America were reviewed and their reported lethal doses in children or adults (where no pediatric data existed) were identified. The dose units of drugs available in North America were subsequently identified, followed by those dose units that could kill a toddler upon ingestion of 1-2 dose units or teaspoonfuls.

RESULTS

Tricyclic antidepressants, antipsychotics, quinine derivatives, calcium channel blockers, opioids, and oral hypoglycemics can kill a toddler with 1-2 dose units. This list of drugs was responsible for 40% of toddler fatalities reported to the American Association of Poison Control Center Toxic Exposure Surveillance System between 1990-2000.

CONCLUSION

Drugs that can kill a toddler with 1-2 dose units should be known to clinicians as such exposures warrant immediate and intensive management. A new system of special labeling of these drugs should be considered.

Comparison of Patient Questionnaires and Plasma Assays in Intentional Drug Overdoses

Our aim was to explore the agreement between clinically collected information on purported drug intake and plasma data in intentional drug overdose. We included all subjects with intentional drug overdose above 15 years of age consecutively admitted to the Emergency Department of the University Hospital during 4 months. Information about drugs used and sources of this information was collected and compared to presence of drug in plasma, concerning four drugs with high toxic potential (tricyclic antidepressants, meprobamate, paracetamol and ethanol). Sensitivity, specificity, predictive positive and negative values of all sources of information pooled were assessed for each drug. 413 intentional drug overdoses were included, 66% with more than one drug. According to clinical information, 8% took tricyclic antidepressants, 11% meprobamate, 9% paracetamol and 41% ethanol. Systematic plasma assays confirmed this in 59% of cases for tricyclic antidepressants, 76% for meprobamate and ethanol, and 77% for paracetamol. Plasma concentrations were considered toxic in 28% of cases for tricyclic antidepressants, 65% for meprobamate, 43% for ethanol and never for paracetamol. Tricyclic antidepressants and meprobamate were found unexpectedly in 3%, paracetamol in 7% and ethanol in 6%. Toxic concentrations were found only with meprobamate. The risk of erroneous, clinically collected information was greater by excess (25 to 40% false positives) than by lack (3 to 7% false negatives). Thus, the consequences of erroneous, clinically collected information were probably more excess cost for the institution than medical risk for the patients. However these results found at the population level may not be true at an individual level.

Antidepressant-related deaths and antidepressant prescriptions in England and Wales, 1998-2000

BACKGROUND

Deaths from antidepressants continue to account for a substantial proportion of drug-related deaths.

AIMS

To investigate the relative toxicity of the major classes of antidepressant drugs, with the specific objective of assessing this in relation to the cause of death; and to analyse the deaths where there were multiple mentions of antidepressant drugs or other psychoactive drugs with antidepressants.

METHOD

Mortality data were collected from the National Programme of Substance Abuse Deaths, and antidepressant prescription data were collected.

RESULTS

Most deaths from antidepressant drugs were suicides (80%). Tricyclic antidepressants (TCAs) accounted for more drug mentions than did other antidepressant drugs (12 per million prescriptions). Selective serotonin reuptake inhibitors (SSRIs) were associated with a significantly lower risk of toxicity, but 93% of deaths from SSRIs occurred in combination with other drugs, especially TCAs (24.5%). In 'combination' deaths patients were significantly more likely to have had a history of drug misuse.

CONCLUSIONS

The efficacy and safety of augmentation therapy with TCAs in SSRI-resistant patients should be monitored carefully, and patients prescribed antidepressants should be screened for drug use/misuse.

Antidepressant poisoning deaths in New Zealand for 2001

AIM

To compare the rates of death per volume of drug dispensed for antidepressants in New Zealand.

METHODS

Deaths from antidepressant poisonings were identified from the reports of coronial inquiries for New Zealand in 2001. Prescriptions for antidepressant medications were identified from the PharmHouse database from 1 January 2001 to 31 December 2001. The rates of deaths (95% CI) per prescription, tablet/capsule or defined daily dose were calculated for individual antidepressants and classes of antidepressant.

RESULTS

There were 200 poisoning deaths recorded in the database for New Zealand in 2001. Antidepressants were involved in 41 deaths, and death was attributed to an antidepressant in 23 cases. There were 5.52 (95% CI 3.85-7.68) deaths per 100 000 prescriptions for tricyclic antidepressants (TCAs) and 2.51 (1.57-3.79) deaths per 100 000 prescriptions for selective serotonin reuptake inhibitors (SSRIs). There was marked variability in rates of death per volume of drug dispensed between individual antidepressants.

CONCLUSIONS

SSRIs have lower rates of death per volume of drug dispensed than TCAs and there is also variation in these rates within these classes of drugs. Toxicity in overdose should be considered when prescribing antidepressants.

Use of dosage as a triage guideline for unintentional cyclic antidepressant (UCA) ingestions in children

Triage guidelines for unintentional cyclic antidepressant (UCA) ingestions vary widely, with limited supportive evidence. All records of UCA ingestion reported to 4 certified regional poison centers were evaluated for the years 1998 through 2000. Inclusion criteria included age </=6 years patients with a known outcome and known ingested dose by history. Exclusion criterion was polydrug ingestion. Two hundred forty-six cases were evaluated. The mean age was 2.4 years (standard deviation, +/-1.2 y). One hundred thirty-six patients (55%) were managed in a hospital. One hundred ten patients were managed at home with observation and telephone follow up. Symptoms reported were drowsiness (n = 59), tachycardia (n = 4), agitation (n = 2), coma (n = 2), respiratory depression (n = 1), and ataxia (n = 1). Medical outcome was reported as no effect (n = 185; 75%), minor effect (n = 57; 23%), moderate effect (n = 2; 1%); and major effect (n = 2; 1%). Mean dosage of patients with and without symptoms was 6.3 mg/kg (+/- 9.3) and 2.9 mg/kg (+/- 3.1), respectively. Forty-three of 57 patients (75%) with minor symptoms reported a dosage of <5 mg/kg. All patients with a moderate or major outcome (n = 4) reported a dosage of >5 mg/kg. The majority of UCA ingestions produced limited or no symptomatology. In this series, all children with ingestions of <5 mg/kg developed no or minor effects. Home monitoring might be appropriate in such cases.

Delayed poisoning emergencies

The American Association of Poison Control Centers (PCCs) has a nationwide toll-free number for contacting regional poison centers. To be automatically connected to a local poison center, call 800/222-1222. EMS providers should follow local protocols to determine how to contact PCCs, either directly or through on-line medical control. Most experts agree that PCCs are a reliable and current source of information on the assessment and treatment of poisoning emergencies.

Reversal of severe tricyclic antidepressant-induced cardiotoxicity with intravenous hypertonic saline solution

A 29-year-old woman ingested 8 g of nortriptyline and presented to the emergency department with coma, hypotension, and widened QRS interval. After intubation, gastric lavage, hyperventilation, and therapy with intravenous normal saline solution, sodium bicarbonate boluses (rapid intravenous push), and high doses of norepinephrine and dopamine, she transiently improved, only to deteriorate on arrival to the ICU. Because her arterial pH was alkalemic at 7.5 at this point, she was given additional sodium in the form of 200 mL of 7.5% NaCl by means of rapid intravenous infusion (intravenous push) to treat hypotension and widening QRS interval with ventricular ectopy. A continuous 12-lead ECG documented narrowing of her QRS interval with concomitant improvement of hypotension within 3 minutes of hypertonic saline solution infusion. Hypertonic saline solution should be considered for wide complex QRS and hypotension caused by tricyclic antidepressant-induced cardiotoxicity that is unresponsive to standard therapies.

Evaluation of tricyclic antidepressant false positivity in a pediatric case of cyproheptadine (periactin) overdose

CASE REPORT

The authors report a case of pediatric cyproheptadine toxicity, initially misdiagnosed as tricyclic toxicity based on the results of a preliminary rapid toxicological serum screen. Although such cross-reactivity has been reported, the chemical basis of this observation has not yet been evaluated. By GC/MS methods and HPLC assays adapted for the detection of tricyclic compounds, the authors confirmed that cyproheptadine was indeed responsible for this patient's toxicity. In addition, the authors identified the presence of a cyproheptadine metabolite in the patient's serum. Further testing in an immunoassay-based toxicologic screen demonstrated some cross-reactivity exhibited by the patient's serum, but not the parent compound. These findings showed that the cross-reactivity correlated with the presence of the cyproheptadine metabolite, highlighting the value of confirmatory toxicologic testing of routine rapid toxicologic screens.

Co-proxamol and suicide: a study of national mortality statistics and local non-fatal self poisonings

OBJECTIVES

To examine the incidence of suicides due to co-proxamol compared with tricyclic antidepressants and paracetamol, and to compare fatality rates for self poisonings with these drugs.

DESIGN

Analysis of routinely collected national and local data on suicides and self poisonings.

SETTING

Records of suicides in England and Wales 1997-9; non-fatal self poisonings in Oxford District 1997-9.

DATA SOURCES

Office for National Statistics and Oxford monitoring system for attempted suicide.

MAIN OUTCOME MEASURES

Incidence of suicides with co-proxamol or tricyclic antidepressants or paracetamol. Ratios of fatal to non-fatal self poisonings.

RESULTS

Co-proxamol alone accounted for 5% of all suicides. Of 4162 drug related suicides, 18% (766) involved co-proxamol alone, 22% (927) tricyclic antidepressants alone, and 9% (368) paracetamol alone. A higher proportion of suicides in the 10-24 year age group were due to co-proxamol than in the other age groups. The odds of dying after overdose with co-proxamol was 2.3 times (95% confidence interval 2.1 to 2.5) that for tricyclic antidepressants and 28.1 times (24.9 to 32.9) that for paracetamol.

CONCLUSIONS

Self poisoning with co-proxamol is particularly dangerous and contributes substantially to drug related suicides. Restricting availability of co-proxamol could have an important role in suicide prevention.

Relative toxicity of venlafaxine and selective serotonin reuptake inhibitors in overdose compared to tricyclic antidepressants

BACKGROUND

Selective serotonin reuptake inhibitors (SSRIs) and venlafaxine have been regarded as less toxic in overdose than tricyclic antidepressants (TCAs). Within the TCAs, dothiepin has greater toxicity. Venlafaxine may be more toxic than SSRIs.

AIM

To assess the toxicity in overdose of venlafaxine and SSRIs compared to TCAs, and of dothiepin compared to other TCAs.

DESIGN

Cohort study of prospectively collected data from the Hunter area, NSW, Australia.

METHODS

First admissions with antidepressant deliberate self-poisoning (DSP) (November 1994 to April 2000) were identified; the presence of seizures, life-threatening arrhythmias, coma, serotonin toxicity or ICU admission, and QRS duration were noted.

RESULTS

There were 538 admissions, with no deaths. The odds ratio (OR) for seizures with dothiepin vs. other TCAs was 3.4 (95%CI 1.2-9.9). Seizures occurred in 7/51 (14%) venlafaxine overdoses; all patients with seizures consumed > or =900 mg. The OR for seizures vs. TCAs was 4.4 (95%CI 1.4-13.8). Coma was less likely with venlafaxine and SSRIs. SSRIs, but not venlafaxine, were less likely to prolong the QRS to > or =100 ms. ICU admission was less likely for SSRIs. Serotonin toxicity was much more common with venlafaxine and SSRIs.

DISCUSSION

Venlafaxine and dothiepin are pro-convulsant in overdose. Venlafaxine is more likely to cause serotonin toxicity, but less likely to cause coma than TCAs. SSRIs are less likely to cause coma, require ICU admission, or prolong the QRS, but are more likely to cause serotonin toxicity. Antidepressants other than TCAs or venlafaxine should be considered in patients at risk of seizure or suicide.

Towards evidence based emergency medicine: best BETs from the Manchester Royal Infirmary. Glucagon in tricyclic overdose

A short cut review was carried out to establish whether the addition of glucagon to standard treatments improves clinical outcome in patients who have taken an overdose of tricyclic antidepressants. Altogether 31 papers were found using the reported search, of which three presented the best evidence to answer the clinical question. The author, date and country of publication, patient group studied, study type, relevant outcomes, results, and study weaknesses of these best papers are tabulated. A clinical bottom line is stated.

Toxicokinetics of nortriptyline and amitriptyline: two case reports

Two cases are presented of intentional intoxications with the tricyclic antidepressants (TCAs) nortriptyline (NT) and amitriptyline (AT). The peak plasma concentrations were 2290 microg/L and 2900 microg/L, respectively. The active metabolites E-10-hydroxynortriptyline (EHNT) and Z-10-hydroxynortriptyline (ZHNT) profiles were quite different as monitored for 5 to 10 days after presumed drug intake. In conclusion, these cases illustrate that (1) metabolite formation and elimination after intake of an overdose dose of NT and AT are stereoselective, and (2) NT and EHNT toxicokinetics and toxicodynamics are quite different. It also shows that a patient with a severe TCA overdose can still survive if he or she receives appropriate and quick supportive care, even if the prognostic markers QRS time, coma grade, and serum TCA levels predict poor outcome.

National academy of clinical biochemistry laboratory medicine practice guidelines: recommendations for the use of laboratory tests to support poisoned patients who present to the emergency department

BACKGROUND

Exposure to drugs and toxins is a major cause for patients' visits to the emergency department (ED).

METHODS

Recommendations for the use of clinical laboratory tests were prepared by an expert panel of analytical toxicologists and ED physicians specializing in clinical toxicology. These recommendations were posted on the world wide web and presented in open forum at several clinical chemistry and clinical toxicology meetings.

RESULTS

A menu of important stat serum and urine toxicology tests was prepared for clinical laboratories who provide clinical toxicology services. For drugs-of-abuse intoxication, most ED physicians do not rely on results of urine drug testing for emergent management decisions. This is in part because immunoassays, although rapid, have limitations in sensitivity and specificity and chromatographic assays, which are more definitive, are more labor-intensive. Ethyl alcohol is widely tested in the ED, and breath testing is a convenient procedure. Determinations made within the ED, however, require oversight by the clinical laboratory. Testing for toxic alcohols is needed, but rapid commercial assays are not available. The laboratory must provide stat assays for acetaminophen, salicylates, co-oximetry, cholinesterase, iron, and some therapeutic drugs, such as lithium and digoxin. Exposure to other heavy metals requires laboratory support for specimen collection but not for emergent testing.

CONCLUSIONS

Improvements are needed for immunoassays, particularly for amphetamines, benzodiazepines, opioids, and tricyclic antidepressants. Assays for new drugs of abuse must also be developed to meet changing abuse patterns. As no clinical laboratory can provide services to meet all needs, the National Academy of Clinical Biochemistry Committee recommends establishment of regional centers for specialized toxicology testing.

[Identification of the drugs in the mixture using thin-layer chromatography in sudden poisoning cases]

The problem of acute intoxication has become very urgent now due to a great number of various chemical preparations accumulated during the last decades in the environment. Intoxications with psychotropic drugs and their mixtures form the significant part of the intoxications; there is an increasing tendency of intoxication with several preparations at a time. Amitriptyline and codeine are the preparations, which more frequently can cause intoxication. Fluoxetine is one of the newest and often used antidepressants. Under certain circumstances, like overdose, using all preparations together, long term using or using for suicide, these preparations can be even a cause of death. In such cases amitriptyline, fluoxetine and codeine become the objects of chemical-toxicological analysis. The possibility of the separation and identification of amitriptyline, fluoxetine and codeine in the mixture using thin-layer chromatography was established. Dragendorf reagent, modified by Munje, is most suitable for the spray-distinct of the chromatographic plates for all three substances. Amitriptyline research limit, using this developer, is 0.4 microg, fluoxetine--1.6 microg, codeine--0.8 microg. Most acceptable for separation the components of the mixture are 5 mobile phases: 1. Diethyl acetate-methanol-ammonium hydroxide (concentrated solution) (85:10:5). Amitriptyline, fluoxetine and codeine R(f) medium values respectively are 0.94; 0.63; 0.51. 2. Buthylacetate-methanol-ammonium hydroxide (concentrated solution) (85:10:5). Amitriptyline, fluoxetine and codeine R(f) medium values respectively are 0.65; 0.24; 0.15. 3. Cyclohexane-diethyl acetate-diethyl amine (70:15:15). Amitriptyline, fluoxetine and codeine R(f) medium values respectively are 0.93; 0.75; 0.37. 4. Cyclohexane-buthylacetate-diethyl amine (70:15:15). Amitriptyline, fluoxetine and codeine R(f) medium values respectively are 0.92; 0.51; 0.25. 5. Acetone-1,4-dioxane-ammonium hydroxide (concentrated solution) (30:68:2). Amitriptyline, fluoxetine and codeine R(f) medium values respectively are 0.82; 0.62; 0.42. Recommended methodology for the separation and identification of amitriptyline, fluoxetine and codeine in the mixture using thin-layer chromatography is statistically reliable: when confidence level is 0.95, relative error is less than 0.05; standard deviation is from 0.007 to 0.03. Recommended methodology suits for mixture, extracted from biological liquids, components separation and identification.

[Intoxication with tricyclic antidepressants in 2000: regional toxicological poison data from the center in Lublin]

The thirty eight tricyclic antidepressants (TCA) intoxicated patients were hospitalised during 2002 year in the Regional Toxicological Center in Lublin. The attempted suicides were the reason of administrating TCA drugs. All hospitalised patients did not suffer from cardio-vascular diseases. Analyzing the cases of patients intoxicated with TCA we took into account: heart rate, blood pressure, ECG record--QRS, QT, PQ, ST abnormalities, blood gases ((pH, pCO2, pO2, saturation), and serum drug concentration. The 50% of our TCA intoxicated patients demonstrated cardio-vascular symptoms confirming our expectations.

[Clinical evaluation of triage as drug-of-abuse test kit]

There are about 60,000 chemical substances which may cause poisoning. Identifying the cause substances is, therefore, very important for patient at emergency department. Triage is an immunoassay kit for the qualitative test for the metabolites of 8 major abuse drugs in urine. We assessed the usefullness of Triage on two patient groups. The first Group consists of the patients considered having not taken substances at initial diagnosis; the second Group consists of the patients considered having taken substances. The result are as follows. 1) The rate of Triage positive patients in the first Group were: attempt-suicide 23%, coma 24%, shock 10%, trauma 7%, respectively. Except for the habitually used medicine, narcotic and stimulant drugs were detected. In the first Group, negative result of Triage was effective in diagnosing the patients as not poisoned, excluding the possitivity of 8 major drugs usage. 2) The rate of Triage positive patients in the second Group were very high: attempt-suicide 77%, coma 51%, shock 57%, trauma 30%, respectively, showing mostly any of 8 major drugs were the cause of poisoning. In the second Group, positive result of Triage was effective in diagnosing the patient as poisoning or as coexisting poisoning with other diseases. 3) The specificity of Triage diagnosis in the first Group was 80% (113/142). The specificity and the sensitivity in the second Group were 64% (50/78) and 97% (74/76), respectively. These results means that Triage is very useful for diagnosis on 8 major drugs poisoning. 4) Triage is efficient for identifying the cause substances in drug poisoning and, therefore, can save medical expense. Triage is a very useful test kit at emergency department.

Gastric lavage in tricyclic antidepressant overdose

A short cut review was carried out to establish whether gastric lavage is indicated after tricyclic antidepressant overdose. Altogether 82 papers were found using the reported search, of which one presented the best evidence to answer the clinical question. The author, date and country of publication, patient group studied, study type, relevant outcomes, results and study weaknesses of this best paper are tabulated. A clinical bottom line is stated.

The toxicity of antidepressant poisoning: is it changing? A comparative study of cyclic and newer serotonin-specific antidepressants

AIM

To compare the clinical features of cyclic antidepressant and newer, non-cyclic, serotonin-specific antidepressant poisoning.

METHODS

Comparitive, descriptive study of all antidepressant overdose patients admitted to a hospital toxicology service from February 1997 to April 2001. Patient data were entered prospectively into a dedicated toxicology database for subsequent analysis.

RESULTS

There were 256 admissions for antidepressant poisoning (17.5% of all poisoning admissions). Cyclic antidepressant poisoning comprised 43% of antidepressant admissions. Statistically significant differences between the two groups included: cyclic antidepressant group had longer median length of stay (23.1 vs 15.9 h, P = 0.0008), greater need for endotracheal intubation (31%vs 4%, OR = 11.5, P < 0.0001) and higher incidence of seizures (7.2%vs 0.7%, OR = 10.4, P = 0.01), faster median pulse rate, longer QRS-interval on admission, and longer intensive care unit stays. However, non-cyclic, serotonin-specific antidepressant poisonings involved larger doses of antidepressants and were more likely to ingest other medications along with these. Serotonin syndrome was only seen in non-cyclic, serotonin-specific poisoning (10.3%, OR = 26.6, P = 0.0002). Patients with serotonin syndrome had a longer median hospital stay (46 vs 16 h, P < 0.0002) compared to other non-cyclic, serotonin-specific patients. There were no deaths during the study period.

CONCLUSIONS

Cyclic antidepressants still comprise a significant proportion of antidepressant poisoning and result in more significant morbidity than non-cyclic, serotonin-specific poisoning. Clinicians should also be aware that non-cyclic, serotonin-specific poisoning may result in the development of serotonin syndrome. This was the most significant toxic effect noted following non-cyclic, serotonin-specific poisoning in this study.

Role of lead aVR in evaluation of 12-lead electrocardiogram

Diagnostic information obtained from the evaluation of the unipolar lead aVR in electrocardiography (ECG) is not fully appreciated, and therefore, the lead aVR is often overlooked in the routine evaluation of the 12-lead ECG. Lead aVR may supplement clinical information, aiding in the management of several cardiovascular conditions. The role of the lead aVR in evaluation of various clinical conditions is reviewed.

[Increasing significance of antidepressants in deliberate self-poisoning]

BACKGROUND AND OBJECTIVE

Antidepressant drugs are frequently used in deliberate self-poisoning resulting in a major risk for the patients due to their cardiac and central-nervous toxicity. In the present study the cases of intoxications consulting our Poison Center should be analysed illustrating recent results and trends about self-poisoning with antidepressants.

PATIENTS AND METHODS

During the study period from 1995 to 2001 35 394 inquiries concerning deliberate self-poisoning were registered in our Poison Center. The substance used, age and gender of the patient as well as the degree of the observed symptoms were documented. Thereby, antidepressant drugs were grouped in tricyclic antidepressants (TCA), selective serotonin reuptake inhibitors (SSRI) and other antidepressants.

RESULTS

The use of antidepressants in deliberate self-poisoning continuously increased during the study period from 17.3 % to 22.9 % with SSRI and other antidepressants being observed more frequently as compared to TCA. Antidepressant drugs were mainly used from female patients and in the age group between 35 and 54 years. Antidepressant drugs caused severe intoxications and deaths more frequently as the remainder substances with TCA showing higher rates of complications as compared to SSRI and other antidepressants.

CONCLUSIONS

In recent years, an increasing importance of antidepressant drugs in deliberate self-poisoning was determined particularly concerning female and middle-aged patients. Due to the changing prescribing patterns larger numbers of intoxications with SSRI and other antidepressants were observed representing an advantage with respect to the reduced rate of complications known for these substances as compared to TCA. Nevertheless, the averagely more severe symptoms present in the three groups of antidepressants in comparison to the remainder drug overdoses demonstrated the need for hospitalization and monitoring of intoxications with antidepressants.

Coma blisters, peripheral neuropathy, and amitriptyline overdose: a brief report

BACKGROUND

Coma blisters are most commonly associated with barbiturate and benzodiazepine overdose; however, they have also been described in association with many other substances, including amitriptyline.

OBJECTIVE

To review the literature on the clinical manifestations of coma blisters in the setting of amitriptyline overdose.

METHODS

Case report and literature review.

RESULTS

Coma blisters in association with amitriptyline overdose have rarely been documented in the literature. Of the few reported cases, peripheral neuropathy has been present two (including our case report) out of four times.

CONCLUSION

Amitriptyline is known to impair endothelial cell tight junction integrity. Thus, individuals with amitriptyline overdose may be predisposed to microvascular damage during the compression imposed from a comatose state. This may help to explain the tendency for patients to present with the interesting triad of coma, blisters, and neuropathy.

Diagnostic data in clinical toxicology--should we use a Bayesian approach?

A number of toxidromes (toxicology syndromes) have been described for various poisonings and are promoted as a means of reaching a diagnosis in patients presenting with unknown poisonings. Many are based entirely on deductive reasoning from the known pharmacological effects of these drugs rather than on documented clinical experience. In this paper, we used our database, where we have recorded clinical signs on presentation in unselected poisonings to explore how clinical signs actually alter the odds of ingestion of different poisons. Many signs substantially altered the list of drugs likely to have been ingested. We found that the most important factor determining whether an unconscious patient had ingested a particular drug was how frequently that drug was taken generally (i.e., the a priori probability), rather than the presence of any particular physical sign. It also follows that our (or anyone else's) intuitive or deductive approach to diagnosis, derived from experience, will not necessarily be very useful at another place where predominantly different drugs are involved in poisoning. Our data were used to derive odds ratios as a measure of the strength of association of physical signs or investigations with ingested poisons. These can be used to develop simple diagnostic algorithms orflow charts to identify the most likely drugs ingested, or using more complicated programming, could also be used to calculate the precise probability of different drug-ingestion using Bayes' Theorem. The usefulness (i.e., external validity) of clinical research from other centers can also be determined.

[Role of abnormalities of the lung surfactant system in the development of respiratory failure in critical states caused by acute neurotoxic poisoning]

Clinical data on the surfactant system of the lungs during poisoning with neurotoxic toxins are presented and approaches to drug correction of lung system disorders in severe intoxication with neurotoxic agents are offered.

Efficacy of long duration resuscitation and magnesium sulphate treatment in amitriptyline poisoning

A single dose of cyclic antidepressants leads to death in childhood. Myocardial depression and ventricular arrhythmia are the severe side effects in cyclic antidepressant overdose. A 23-month-old boy was brought to hospital because 36 mg/kg of amitriptyline had been taken. Cardiopulmonary resuscitation was applied for 70 minutes due to cardiac and respiratory arrest. Circulation was restored after resuscitative efforts. However, ventricular tachycardia was detected which did not respond to lidocaine, bicarbonate and cardioversion treatment. Magnesium sulphate treatment was started and cardiac rhythm normalized. No side effects were observed. The duration of resuscitation should be extended in cases of cardiopulmonary arrest secondary to tricyclic antidepressants intoxication. It should be continued at least for 1 hour. Magnesium sulphate was found to be extremely effective in a case of amitriptyline intoxication refractory to treatment.

[External ophthalmoplegia caused by amitriptyline poisoning]

Drug-induced ocular motor disorders occurring during coma may be difficult to distinguish from structural cerebral lesions. We recently encountered a case of reversible amitriptyline-induced external ophthalmoplegia, which was first described by Mladinich and Carlow in 1977. We suggest that the mechanism for gaze paresis and loss of vestibulo-ocular reflex due to amitriptyline overdose involves the modulation of neurons of the pontine paramedian reticular formation, the rostral fasciculus longitudinalis medialis, and the vestibulo-ocular reflex. Clinical features that might be useful when distinguishing amitriptyline-induced ophthalmoplegia from structural brain lesions--such as basilar thrombosis--include the preservation of corneal response, purposeful withdrawal from noxious stimuli, rapid recovery within 24 hours, and the reversal of symptoms by physostigmine.

Serial electrocardiographic changes as a predictor of cardiovascular toxicity in acute tricyclic antidepressant overdose

Tricyclic antidepressant agents continue to be a leading cause of significant morbidity and mortality in reported poisonings involving pharmaceutical agents. Although the history and physical examination play an important role in the assessment of patients with tricyclic antidepressant overdose, the presence of anticholinergic features on examination cannot predict the severity of the overdose. Several clinical variables, in particular electrocardiographic (ECG) changes, have been proposed as a guide to determine the severity of the tricyclic antidepressant poisoning. The authors describe a patient with tricyclic antidepressant overdose who presented with altered mental status and whose serial ECG changes played a significant role in diagnosing and predicting the impending cardiovascular toxicity. The role of ECG changes in making the diagnosis and assessing the severity of the tricyclic antidepressant overdose is reviewed.

Treatment of severe tricyclic antidepressant overdose with extracorporeal sorbent detoxification

Tricyclic overdose can be a medical emergency, and therapy with intravenous bicarbonate is not always successful in preventing cardiac toxicity or coma. Mortality in patients developing these complications is from 1% to 15%. Extracorporeal detoxification with sorbents has been used in treatment of patients with very high drug levels and declining clinical condition. Ten patients with serious drug overdose caused by tricyclics failed to respond quickly to standard therapy and were in stage 3-4 encephalopathy. Nine of these patients were on respirator support, 5 had hypotension, and 6 had QRS widening. Average level was 1,423 microg/L at presentation. Enteral activated charcoal and intravenous (IV) bicarbonate were initiated in the emergency room. The patients were treated for 3 to 4 hours with the Liver Dialysis Unit, a hemodiabsorption device using a cellulosic plate dialyzer and sorbent suspension as dialysate. Inflow and outflow blood levels indicated that the hemodetoxifier removed modest amounts of the tricyclics, metabolites, and other consumed drugs. The clinical improvement of the patients was dramatic, with patients reaching stage 0 or 1 encephalopathy during the treatment. Ventilator support was removed at the end of treatment for 3 patients who had not already developed pneumonia, and for others was prolonged up to 48 hours because of pneumonia, rather than mental status. Average length of stay in the intensive care unit (ICU) was 4.8 days (range 1 to 7 days). None of the patients died despite their high risk for ventricular arrhythmias, seizures, and death. Clinical improvement may have been attributable to removal of free drug from the blood or to removal of drug metabolites.