Clinical effects and treatment of imipramine and amitriptyline poisoning in children

Overdoses with Tricyclic Antidepressants

The authors present a 46-year-old female and a 14-month-old female following ingestion of an overdose of tricyclic antidepressants, amitriptyline and imipramine, respectively. The discussion, following the cases, reviews the toxic manifestations of the antidepressive agents, i.e., CNS depression, agitation, delirium, coma, cardiac manifestations and anticholinergic effects. Review of appropriate treatment, particularly the use of physostigmine, is also presented.

Amitriptyline overdose in emergency department of university hospital: evaluation of 250 patients

OBJECTIVE

The purpose of this study was to evaluate the patients with acute amitriptyline poisoning and investigate predictive factors for the development of life-threatening complications.

METHODS

Demographics, clinical, laboratory, and electrocardiographic (ECG) findings of 250 patients were evaluated retrospectively. Predictive parameters for the development of serious complications were studied.

RESULTS

Median age of patients was 14.6 years, of which, 70% of patients were female and 66% were in pediatric age group. The most common pathological clinical finding and laboratory abnormality were alteration of consciousness and hyponatremia. The rate of convulsive seizure, arrhythmia, and respiratory depression were 17 (6.8%), 16 (6.4%), and 11 (4.4%), respectively. These complications were more seen in pediatric patients than adults (15.8% and 1.2%). The incidence of hyponatremia was more in pediatric patients and severe poisoning groups (38.8 and 53.4%, respectively). The levels of amitriptyline and nortriptyline were significantly higher in the group with complications than the group without complications (p < 0.05). All adult patients were discharged with good prognosis. In pediatric age group, one patient was discharged with severe neurological sequelae and one patient died. QRS duration >100 ms, long corrected QT duration interval, and low Glasgow Coma Score (GCS) at admission were identified as independent risk factors for the development of life-threatening complications (odds ratio: 69.4, 1.9, and 1383, respectively; p < 0.05).

CONCLUSION

Amitriptyline poisoning may be associated with life-threatening complications, especially in pediatric age group and in patients with hyponatremia. Low GCS, presence of hyponatremia, high serum drug levels, and pathological ECG findings on admission may be helpful in predicting the development of complications and poor prognosis.

Hemoperfusion with Amberlite resin in the treatment of self-poisoning

Ten patients with various intoxications were treated with resin hemoperfusion. Three of four patients with grade IV coma due to tricyclic antidepressant (TCA) poisoning could be extubated during or on termination of hemoperfusion. Clearance values of 135--185 and 190--200 ml/min were obtained for amitriptyline and nortriptyline, respectively. One patient with severe chloral hydrate poisoning could be extubated after less than one hour's hemoperfusion. A clearance of 140 ml/min was obtained in a uremic patient with AV block II due to digitoxin intoxication. Four patients with mushroom poisoning were treated with combined hemoperfusion-hemodialysis. A transient fall in platelet count was seen in all patients. Resin hemoperfusion is of definite value in selected, severe cases of self-poisoning with psychotropic drugs such as TCA and possibly in cases of mushroom poisoning where the prognosis with hemodialysis and supportive therapy is doubtful.

Clinical, electrocardiographic, and laboratory findings in children with amitriptyline intoxication

BACKGROUND

Amitriptyline is one of the major tricyclic antidepressants, and the data on amitriptyline poisoning in children are limited.

OBJECTIVES

To present our experiences with amitriptyline poisoning in children, particularly with regard to its effects on electrocardiogram (ECG) and relation with clinical status.

METHODS

Clinical, laboratory, and electrocardiographic findings in 52 children admitted with amitriptyline poisoning were reviewed. Patients were divided into 2 groups according to age, as 6 years or younger (group A) and older than 6 years (group B).

RESULTS

Mean age was 4.6 +/- 3.0 years. Thirty-one patients were male, and 41 were 6 years or younger. Ingested amitriptyline dose was known in 23 patients (range, 2.3 mg/kg-27 mg/kg). The most frequent findings were lethargy (76.9%), sinus tachycardia (57.7%), and coma (48.1%). Four patients had a history of convulsion. The most common laboratory abnormalities were hyponatremia (26.9%) and leukocytosis (25%). Elevated transaminase levels were observed in 4 patients. In ECG, 11 (22.4%) patients had QTc prolongation and in 4 (8.2%) of them, it was significant. In 4 patients (8.2%), the QRS duration was 100 ms or longer and in 15 patients, the R wave in aVR was 3 mm or longer. The frequencies of clinical, laboratory, and electrocardiographic findings were similar between the 2 age groups (P > 0.05). No clinically apparent arrhythmias were observed. The positive predictive value of a widened QRS was 100% in terms of coma. None of the patients with an R wave in aVR of less than 3 mm developed convulsion; thus, the negative predictive value of an R wave in aVR of 3 mm or longer was 100% in terms of convulsion.

CONCLUSIONS

Amitriptyline poisoning may result in severe toxicity. Frequencies of clinical, laboratory, and ECG findings were similar in the 2 age groups. Amitriptyline overdose results in some ECG changes that can possibly help to predict the results of poisoning. Absence of an R wave in aVR of 3 mm or longer predicts seizures with a high negative predictive value, and a QRS duration of 100 or longer ms predicts coma with a high positive predictive value.

Tricyclic antidepressant poisoning: an evidence-based consensus guideline for out-of-hospital management

A review of U.S. poison center data for 2004 showed over 12,000 exposures to tricyclic antidepressants (TCAs). A guideline that determines the conditions for emergency department referral and prehospital care could potentially optimize patient outcome, avoid unnecessary emergency department visits, reduce healthcare costs, and reduce life disruption for patients and caregivers. An evidence-based expert consensus process was used to create the guideline. Relevant articles were abstracted by a trained physician researcher. The first draft of the guideline was created by the lead author. The entire panel discussed and refined the guideline before distribution to secondary reviewers for comment. The panel then made changes based on the secondary review comments. The objective of this guideline is to assist poison center personnel in the appropriate prehospital triage and management of patients with suspected ingestions of TCAs by 1) describing the manner in which an ingestion of a TCA might be managed, 2) identifying the key decision elements in managing cases of TCA ingestion, 3) providing clear and practical recommendations that reflect the current state of knowledge, and 4) identifying needs for research. This guideline applies to ingestion of TCAs alone. Co-ingestion of additional substances could require different referral and management recommendations depending on their combined toxicities. This guideline is based on the assessment of current scientific and clinical information. The panel recognizes that specific patient care decisions may be at variance with this guideline and are the prerogative of the patient and the health professionals providing care, considering all the circumstances involved. This guideline does not substitute for clinical judgment. Recommendations are in chronological order of likely clinical use. The grade of recommendation is in parentheses. 1) Patients with suspected self-harm or who are the victims of malicious administration of a TCA should be referred to an emergency department immediately (Grade D). 2) Patients with acute TCA ingestions who are less than 6 years of age and other patients without evidence of self-harm should have further evaluation including standard history taking and determination of the presence of co-ingestants (especially other psychopharmaceutical agents) and underlying exacerbating conditions, such as convulsions or cardiac arrhythmias. Ingestion of a TCA in combination with other drugs might warrant referral to an emergency department. The ingestion of a TCA by a patient with significant underlying cardiovascular or neurological disease should cause referral to an emergency department at a lower dose than for other individuals. Because of the potential severity of TCA poisoning, transportation by EMS, with close monitoring of clinical status and vital signs en route, should be considered (Grade D). 3) Patients who are symptomatic (e.g., weak, drowsy, dizzy, tremulous, palpitations) after a TCA ingestion should be referred to an emergency department (Grade B). 4) Ingestion of either of the following amounts (whichever is lower) would warrant consideration of referral to an emergency department: an amount that exceeds the usual maximum single therapeutic dose or an amount equal to or greater than the lowest reported toxic dose. For all TCAs except desipramine, nortriptyline, trimipramine, and protriptyline, this dose is >5 mg/kg. For despiramine it is >2.5 mg/kg; for nortriptyline it is >2.5 mg/kg; for trimipramine it is >2.5 mg/kg; and for protriptyline it is >1 mg/kg. This recommendation applies to both patients who are naïve to the specific TCA and to patients currently taking cyclic antidepressants who take extra doses, in which case the extra doses should be added to the daily dose taken and then compared to the threshold dose for referral to an emergency department (Grades B/C). 5) Do not induce emesis (Grade D). 6) The risk-to-benefit ratio of prehospital activated charcoal for gastrointestinal decontamination in TCA poisoning is unknown. Prehospital activated charcoal administration, if available, should only be carried out by health professionals and only if no contraindications are present. Do not delay transportation in order to administer activated charcoal (Grades B/D). 7) For unintentional poisonings, asymptomatic patients are unlikely to develop symptoms if the interval between the ingestion and the initial call to a poison center is greater than 6 hours. These patients do not need referral to an emergency department facility (Grade C). 8) Follow-up calls to determine the outcome for a TCA ingestions ideally should be made within 4 hours of the initial call to a poison center and then at appropriate intervals thereafter based on the clinical judgment of the poison center staff (Grade D). 9) An ECG or rhythm strip, if available, should be checked during the prehospital assessment of a TCA overdose patient. A wide-complex arrhythmia with a QRS duration longer than 100 msec is an indicator that the patient should be immediately stabilized, given sodium bicarbonate if there is a protocol for its use, and transported to an emergency department (Grade B). 10) Symptomatic patients with TCA poisoning might require prehospital interventions, such as intravenous fluids, cardiovascular agents, and respiratory support, in accordance with standard ACLS guidelines (Grade D). 11) Administration of sodium bicarbonate might be beneficial for patients with severe or life-threatening TCA toxicity if there is a prehospital protocol for its use (Grades B/D). 12) For TCA-associated convulsions, benzodiazepines are recommended (Grade D). 13) Flumazenil is not recommended for patients with TCA poisoning (Grade D).

Carbamazepine interference with an immune assay for tricyclic antidepressants in plasma

BACKGROUND

Drug toxicological screening is commonly used as a diagnostic tool in patients with suspected toxic ingestion. False positive results due to cross-reactive compounds in drug assays may lead to misdiagnosis and mismanagement, especially when child abuse is suspected.

CASE REPORT

Two of our patients with history of ingestion of carbamazepine were tested positive on screening with the tricyclic antidepressant immunoassay. The immunoassay's known cross-reactivity for carbamazepine is reportedly as low as 0.3%. Plasma samples of our patients were initially considered positive for tricyclic antidepressants because the cross-reaction of carbamazepine gave tricyclic antidepressant concentrations as imipramine equivalent sufficiently above the assay cut-off point (20 ng/mL). Later, confirmatory urine testing of both patients using high-performance liquid chromatography was negative for tricyclic antidepressants.

CONCLUSION

This interference has significant clinical implications, and can be avoided on urine testing using a specific chromatographic assay such as high-performance liquid chromatography.

Ocular adverse effects of neuropsychiatric agents. Incidence and management

Neuropsychiatric agents may adversely affect the eye in various ways. The more frequently encountered effects include corneal oedema and pigmentary changes in the lens and cornea which are induced by phenothiazine derivatives; thioridazine-induced retinopathy; tricyclic antidepressant-induced accommodation interference and glaucoma; and lithium carbonate-induced exophthalmos and papilloedema. Several adverse effects, such as corneal oedema, retinopathy and glaucoma, are vision-threatening, and patients often fail to describe their symptoms properly. A more precise understanding of these conditions is essential for prompt diagnosis and appropriate treatment.

Tricyclic antidepressant overdose: conservative management in a community hospital with cost-saving implications

Reports of late-onset cardiovascular complications following tricyclic antidepressant (TCA) overdose have led to a very conservative approach to these patients. Many patients have been hospitalized for continuous cardiac monitoring, regardless of the clinical presentation. Management algorithms based on clinical predictors of outcome have recently been proposed. We used the algorithm developed by Tokarski and Young to retrospectively evaluate the care of 33 TCA overdose patients admitted to our hospital over a 3-year period. We then identified 11 patients who could have been treated on an outpatient basis had the algorithm been employed. Ten were admitted to a monitored unit and spent a mean of 31.6 +/- 15.64 hours on the unit. None of the 11 patients developed complications during their hospital stay. Use of the algorithm would have resulted in an estimated cost savings of 13 hospital days and $14,000.

Protective effect of flavonoids on drug-induced hepatotoxicity in vitro

Primary cell cultures of neonatal hepatocytes were used to examine the protective effect of flavonoids in the presence of hepatotoxins. Catechin (CAT) and silybin (SIL) protected the hepatocytes against cell injury produced by erythromycin estolate (EE), amitriptyline (AT), nortriptyline (NT), and tert-butylhydroperoxide (TBOOH). Leakage of lactate dehydrogenase (LDH), aspartate aminotransferase (AST) and alanine aminotransferase (ALT), as well as morphological parameters, were used as indices of hepatotoxicity. Hepatocytes were exposed to EE (1 X 10(-4) M and 2 X 10(-4) M), AT, NT, and TBOOH (1 X 10(-4) M and 1 X 10(-3) M) for a 2-h period. These hepatotoxins caused significant LDH, AST, and ALT leakage (P less than 0.05) when compared to untreated control groups. NT was less toxic than its parent compound, AT. Changes in morphology were evident after 1 h of treatment with the toxicants, including: vacuole formation, size deformation and cell necrosis. As the concentration of hepatotoxins was increased, the changes were more pronounced. Pretreatment of the cultures with either CAT or SIL resulted in less enzyme leakage and morphological alterations by the hepatotoxins. The results of this study suggest that CAT and SIL may act by stabilizing the plasma membrane against toxic insult.

The cardiovascular effects of antidepressants

This monograph comprises a review of the cardiovascular effects of the various types of antidepressant drugs in clinical use. The frequency, severity and clinical importance of these effects are placed in perspective. Most antidepressants can cause changes in blood pressure. Both the tricyclic type (TCA) and the monoamine oxidase inhibitors (MAOIs) can produce postural hypotension which may be dose-limiting. In addition, the MAOIs may be associated with severe hypertension when amine-containing foods or medicines are ingested. It is unlikely that therapeutic doses of any available antidepressant drug could impair cardiac contractility. Typical TCAs can cause abnormalities of cardiac conduction and arrhythmias, but this affects less than 5% of patients, mostly to a clinically insignificant extent. Newer compounds such as lofepramine, mianserin, trazodone and viloxazine seem safer in this respect. Reports of an association between therapeutic use of TCAs and sudden death are far from convincing. Overdosage with the MAOIs, lithium and carbamazepine is dangerous but not common; overdose with a TCA is a major source of morbidity and mortality. Lofepramine, mianserin and trazodone are relatively safe in overdose. The use of various antidepressants in patients with hypertension, cardiac failure, angina pectoris, myocardial infarction, or cardiac arrhythmias is discussed and guidelines suggested for the selection and use of antidepressant medication.

Psychoactive agents, seizure production, and sudden death in epilepsy

Major tranquilizers as well as antidepressant agents have been associated with clinical seizures in patients administered these agents. The incidence of such seizures is generally low when these drugs are administered in therapeutic doses. However, administration of large doses of these agents has been associated with many cases of convulsion production. The effects that these drugs have on animal models of epilepsy have been examined. It appears that the phenothiazines act as convulsant agents at lower doses, whereas, at higher doses, they act as anticonvulsant drugs. Antidepressants, on the other hand, appear to exert an anticonvulsant effect at low doses and convulsant effects at high doses. The mechanism by which these agents alter the seizure threshold is not yet known. Clinically, drugs of lower seizure production potential should be substituted for those drugs with greater potential in treating epileptic patients for psychiatric ailments. The problem of sudden death in epileptic patients is one that must be confronted. Sudden death has most frequently been attributed to autonomic dysfunction and cardiac arrhythmia in these patients. The contribution of stress in sudden death production also must be taken into account. In addition, some psychoactive agents have been associated with sudden death as well as cardiac arrhythmia and seizure production. Thus, in light of the possible additivity of the factors involved in the production of sudden death, the administration of a psychoactive agent to an epileptic patient should be approached with caution. Those agents that do not alter cardiac rhythm or seizure threshold should be administered if a psychoactive agent is deemed necessary for the management of psychiatric illness in the epileptic patient.

Epidemiology of fatal tricyclic antidepressant ingestion: implications for management

Although there is a large body of literature documenting the lethal cardiotoxic complications of tricyclic antidepressant (TCA) overdose, the absence of reliable predictive signs has led to a policy of admitting even trivial-appearing overdoses for inpatient observation. A study of 18 fatal cases revealed that with the exception of two that received clearly inadequate medical care, all fatal ingestions developed major signs of toxicity mandating admission within two hours of arrival at the hospital, and the mean time from arrival to death was only 5.43 hours. All patients who died of direct TCA toxicity did so within 24 hours of arrival. In addition, half the fatal cases presented with only trivial signs of poisoning, but deteriorated catastrophically within one hour. These data lead to an algorithm to guide admission of serious cases.

A collection of therapeutic, toxic and fatal blood drug concentrations in man

In order to assess the significance of drug concentrations measured in clinical and toxicological investigations, it is essential that good collections of data are readily available. As a guide to interpreting findings, the present work provides a compilation of therapeutic, toxic and fatal blood concentration ranges of 298 drugs of interest to clinical pharmacologists, clinical toxicologists, and forensic toxicologists. Wherever possible, ranges are expressed concisely in terms of the maximum blood concentrations which account for 10, 50 and 90% of the data collected. They provide easy access to the most reliable information which relates the blood drug concentration to the biological response it produces. Where appropriate, the different toxic effects of a drug and/or the different degrees of severity of toxic symptoms associated with different drug levels are clearly defined. The original sources of all data used are provided to allow the analyst to obtain further analytical, pharmacokinetic and toxicological information should this be necessary. Those factors (e.g. age, capacity for drug metabolism, drug interactions, etc) which can modify the relationship between a drug concentration and the response it produces are briefly discussed.

Antidepressant drugs, convulsions and epilepsy

1 Evidence concerning the convulsant effects of non-monoamine oxidase inhibitor antidepressant drugs has been reviewed. 2 Mianserin is convulsant in therapeutic doses but seizures have not been reported following overdose. 3 The convulsant effects of mianserin are probably no greater than for other non-monoamine oxidase inhibitor antidepressant drugs. 4 Enzyme-inducing anti-epileptic drugs can reduce the peak plasma concentration of mianserin and shorten its elimination half-life, probably by inducing its metabolism.

Anticonvulsant and proconvulsant properties of viloxazine hydrochloride: pharmacological and pharmacokinetic studies in rodents and the epileptic baboon

Viloxazine HCl is evaluated as an anticonvulsant in a wide range of rodent seizure models and in the epileptic baboon (Papio papio). In the maximal electroshock test, the oral ED50 for abolition of tonic extension was 9 mg/kg-1 after 30-min pretreatment (mouse) rising to 30 mg/kg-1 after 60 min (mouse and rat). Comparable ED50 values were also found for protection against tonic extension in the mouse induced by the administration of the chemical convulsants metrazole or 3-mercaptopropionic acid. In DBA/2 mice the ED50 for abolition of tonic extension during sound-induced seizures was 6.8 mg/kg-1 IP (30-min pretreatment). Pharmacokinetic studies in the mouse showed peak plasma levels to occur 30 min following oral doses, with a mean half-life of 58 min. The anticonvulsant plasma concentration was within 0.5 -- 1 microgram/ml-1. In the baboon, significant protection against photomyoclonic responses is observed 1 -- 2h after viloxazine (2.6 mg/kg-1 IV), during which period the plasma concentration was again 0.5-1 microgram/ml-1. After administration of approximately ten-times this latter dose level, i.e. 24 mg/kg-1 IV, a syndrome characterised by an abnormal EEG and, in some instances, seizure activity was observed.

Cardiac arrhythmias and ECG abnormalities in tricyclic antidepressant overdose

Tricyclic antidepressant overdose is widely felt to be associated with cardiac arrhythmias which may occur without warning, sometimes late in the clinical course. For this reason, many institutions routinely monitor cardiac rhythm in such patients for up to 72 h. A retrospective study was carried out to analyze the clinical course of such patients with emphasis on cardiac complications. Thirty-eight cases of TCA overdose were reviewed. Fourteen patients (36.9%) were classified as lethargic or stuporous on admission while 23 (60.5%) were either comatose or semicomatose, nine requiring endotracheal intubation. Patients were continuously monitored an average of 60 h after admission. Admission ECG's were abnormal in a high number of cases, most common abnormalities being sinus tachycardia (43%) and intraventricular conduction defects (24%). Ventricular ectopy was less common (7.8%). ECG abnormalities, with the exception of sinus tachycardia and infrequent PVC's were associated with a severely depressed sensorium and disappeared with neurological improvement, usually in 24 h. No arrhythmias were noted after the patient had become alert. Overall mortality was 2.6%, with no deaths in the adult populations. After a search of the literature, we conclude that intensive care unit monitoring is not indicated for prolonged periods once the patient has otherwise recovered from his acute complications of drug overdose.

Changes in body temperature after administration of adrenergic and serotonergic agents and related drugs including antidepressants

This survey, the third in a series, presents extensive tabulations of literature, primarily since 1965, on thermoregulatory effects of adrenergic and serotonergic agonists and their antagonists including ergot alkaloids, amphetamines, tryptamines, monoamine oxidase inhibitors, tricyclic and other antidepressants, a variety of other agents which alter presynaptic aminergic mechanisms including reserpine, 6-hydroxydopamine, p-chlorophenylalanine, alpha-methyltyrosines, cocaine, guanethidine and bretylium. The information listed includes the species used, route of administration and dose of drug, the environmental temperature at which the experiments were performed, the number of tests, the direction and magnitude of body temperature change and remarks on the presence of special conditions, such as age or lesions, or on the influence of other drugs, such as antagonists, on the response to the primary drug.

Psychological effects caused by drugs in overdose

Drug overdose is a common occurrence which accounts for up to 25% of medical inpatient admissions. Intentional overdose or attempted suicide is the most common cause of overdose, but there are other types of overdose which are often unrecognised as are the effects caused by these overdoses. Iatrogenic overdose occurs frequently and is often unavoidable. Many patients will make mistakes with their treatment and unwittingly suffer from the toxic effects of the drugs they are taking. About 7% of intentional overdose patients who are admitted to hospital have taken the drug for some psychological effect they have been seeking and have taken too much. This group is described as those who take 'drugs for kicks'. As many of the drugs taken cross the blood-brain barrier and exert some toxic effect on the cerebral cortex, secondary psychological disturbances frequently occur in all of these groups of patients, and can sometimes be the only sign of dangerous toxicity. It is important to recognise the patient's gross disturbances of behaviour, thinking and perception as a manifestation of drug toxicity which can be life threatening and often requires intense medical treatment. The range of the psychological response is somewhat limited and there is not a specific psychological disturbance characteristic of the toxicity of each group of drugs. However, there are some reactions which, coupled with the physical symptoms shown by the patient, can help to identify the patient as suffering from the toxic effects of drugs and even give some indication as to the type of drugs taken. This article describes the various psychiatric syndromes caused by drugs in overdose and attempts to identify these with most of the commonly encountered groups of drugs.

[Poisoning due to tricyclic antidepressants in children and adolescents]

During the last decade there has been a substantial increase in the number of poisonings due to tricyclic antidepressants in both children and adults. The main toxic manifestations are of anticholinergic origin, and the most frequent constitute the so-called central anticholinergic syndrome. Most of the deaths result from the cardiac complications. Three cases are presented that illustrate chiefly the toxic manifestations related to the central nervous system. The therapeutic management is reviewed in the light of the metabolism of the tricyclic antidepressants, their pharmacologic action and the mechanism of their toxic effects.

Non-monoamine oxidase inhibitor antidepressants and epilepsy: a review

The literature dealing with the convulsant effects of the antidepressant drugs of the non-monoamine oxidase inhibitor variety is reviews. It is concluded that most of these drugs do lower the seizure threshold and may precipitate seizures even at normal therapeutic doses. The pathophysiology of antidepressant-induced seizures is discussed, and attention is drawn to biochemical differences in those antideprssants that have the least epileptogenic potential or may even be anticonvulsant. The clinical difficulties regarding administration of antidepressant drugs to epileptic patients are mentioned, and some practical advice is offered.

Combined thin-layer and gas-liquid chromatographic identification of tricyclic antidepressants in urine

A combined thin-layer and gas-liquid chromatographic (TLC-GLC) procedure for determination of tricyclic antidepressant drugs in urine is described. GLC on 1.5% OV-17 was utilized to analyzed basic urine extracts directly for the tricyclics and to confirm the identity of spots extracted from thin-layer chromatograms, and TLC was used to confirm the results of these GLC screens. Lower limits of sensitivity for the thin-layer spot extraction procedure were found to range from 2 mug/ml for amitriptyline and imipramine to 10 mug/ml for desipramine and nortriptyline. Turn-around-times for the GLC tricyclic screens were usually less than 1 h. The finding that nortriptyline and desipramine were chemically altered under various extraction conditions was used as a means of confirming the identity of these drugs, and the identity of these chemically altered derivatives was discussed with reference to their low resolution mass spectra.

Seizure activity in photosensitive baboons following antidepressant drugs and the role of serotoninergic mechanisms

Laboratroy and clinical evidence indicates that tricyclic antidepressants lower seizure threshold and in high doses may induce generalised seizures. In baboons with photosensitive epilepsy (Papio papio) the effects of 2 tricyclic antidepressants (imipramine and chlorimipramine) and of maprotiline and Nomi fensine have been studied (i.v. dose range 1-20 mg/kg. Imipramine, chlorimipramine and maprotiline (10 mg/kg i.v.) lowered seizure threshold to a comparable extent, whereas Nomifensine (10 mg/kg i.v-) did not enhance myoclinic responses to photic stimulation. Generalised seizures were seen 15-30 min after imipramine or chlorimipramine (20 mg/kg), and these two drugs showed no difference in their epileptogenicity. Administration of 5-hydroxytryptophan (25 mg/kg i.v.) 90 min before chlorimipramine or imipramine (10 mg/kg) completely blocked the usual augmentation of photically-induced epileptic responses. It is concluded that enhancement of serotoninergic activity following blockade of 5-HT re-uptake within the brain is unlikely to be responsible for enhanced myoclonic responses and epileptogenic seizures seen after tricyclic antidepressants. Nomifensine is significantly less epileptogenic than imipramine or chlorimipramine.

Effect of nomifensine on brain amines and epilepsy in photosensitive baboons

1. The literature, both clinical and experimental, suggests that tricyclic antidepressants are potentially epileptogenic. Using the experimental model of epilepsy provided by the photosensitive baboon, Papio papio, the epileptic potential of four antidepressant drugs, two of which are tricyclic, has been assessed. The drugs used were imipramine 1, 10 and 20 mg/kg, chlorimipramine 1, 10 and 20 mg/kg, maprotiline 1 and 10 mg/kg and nomifensine 10 and 20 mg/kg. In a second series of experiments the 5-hydroxytryptamine (5-HT) precursor 5-hydroxytryptophan (5-HTP) 10 and 25 mg/kg has been administered before administration of imipramine 10 mg/kg and chlorimipramine 10 mg/kg. 2. The results of the experiments indicate that at 10 mg/kg imipramine, chlorimipramine and maprotiline all induce seizures and lower the seizure threshold. In contrast nomifensine at this dose did not alter the seizure threshold. 5-HTP 25 mg/kg administered before the antidepressants, abolished seizures. These results are discussed in the light of other experiments which have attempted to explain the pathophysiology of epileptic seizures following antidepressants, and it is concluded that dopaminergic mechanisms are probably responsible for the differing effect noted with nomifensine.

Sodium bicarbonate treatment for tricyclic antidepressant arrhythmias in children

Sodium bicarbonate has modified or reversed arrhythmias due to tricyclic antidepressants in 11 children. It has proved to be the most clinically effective method of treatment of these arrhythmias in children, and reference is made to experimental studies which support this view.

Treatment of experimental imipramine and desipramine poisoning in the rat

The influence of orally administered activated charcoal on organ concentrations of parenteral imipramine and desipramine was investigated. Ancillary distribution experiments indicated that the gastroenteral cycle of these substances might be more important than the enterohepatic cycle. Nevertheless the effectiveness of repeated activated charcoal dosage in lowering antidepressant concentrations of visceral organs is unpredictable. This is interpreted as a consequence of predominant binding of these drugs in the tissues, in contrast to drugs like acetosal and the barbiturates, which are distributed more evenly in the body water. The conclusion is, that activated charcoal has only limited value as an anitdotal adsorbent in imipramine or desipramine poisoning.

Haemodialysis in imipramine poisoning? An experimental study

In the last several years an increasing number of severe imipramine intoxications have been observed. Though standard principles for the treatment of acute tricyclic poisoning have been established, nonetheless there still exists doubt on the most effective method of tricyclic removal in cases of massive overdose. Haemodialysis was successfully employed until now but has not found general acceptance as only insignificant amounts of imipramine could be recovered from the dialysate. An experimental clearance study was undertaken using radiolabelled imipramine (14C-I) to obtain insight into the usefullness of haemodialysis in imipramine poisoning. 14C-I clearances which were calculated in a closed circuit dialysis system ranged between 18 ml/min and 48 ml/min depending on the constitution of the dialysate, i.e. aqueous or lipid solution. Surprisingly a rapid and significant uptake of imipramine by the plastic material (polyvinylchloride) of the extracorporeal blood line system was detected. This escape of imipramine from the blood into the tubings explains the poor recovery of tricyclics from the dialysate, which discredited haemodialysis as a therapeutical method in imipramine poisoning. The results of our experiments may offer a new method of rapid tricyclic elimination in severe imipramine intoxications.

Tricyclic antidepressant overdosage: experimental studies on the management of circulatory complications

Tricyclic antidepressant overdosage may be complicated by cardiac arrhythmias, which were sometimes difficult to treat prior to the use of sodium bicarbonate. Experiments have been done with several antiarrhythmics in an attempt to define the optimum treatment. Sodium bicarbonate proved the most effective experimentally and this supports our clinical experience. Physostigmine is a useful second drug, having beneficial effects against arrhythmias and central nervous system manifestations of toxicity. Practolol, although reversing the arrhythmias, tends to cause hypotension. Other drugs tried were less effective.

Tricyclic antidepressive poisoning with special reference to cardiac complications

Sixty-eight cases of tricyclic antidepressive (TCA) poisoning are discussed. Cardiac arrest occurred in 8 patients, preceded by minor ECG-abnormalities. Five patients died. All cardiac arrests arose within the first 24 h after TCA ingestion. Fifty-seven patients developed ECG-abnormalities, of which 84% began within the first 6 h after TCA ingestion. ECG-abnormalities and other symptoms (respiratory arrest, coma, convulsion and hypotension) often occurred in the same patients. Treatment is described, and cardiac monitoring for at least the first 24 h is recommended. In cases of severe cardiac (ECG) abnormalities, monitoring is recommended until no ECG abnormalities are observed for at least 12 h. In conclusion, the unrestricted use of TCA is cautioned against, since TCA must be regarded as potentially cardiotoxic.

Amitriptyline and imipramine poisoning in children

The increasing number of children admitted to this hospital with poisoning by tricyclic antidepressants is causing concern. Of 60 children admitted between January 1966 and July 1973, half were admitted in the last 18 months. In 60% of these patients the tricyclic compounds had been prescribed for nocturnal enuresis. One child aged 2 years and 4 months died of imipramine poisoning. It is imperative that all children with poisoning by tricyclic compounds, irrespective of the dosage, are admitted to hospital for continuous cardiac monitoring. Cardiac arrhythmias induced in children by amitriptyline and imipramine are prominent and dangerous.In the earlier years of this survey the antidepressants taken by children had usually been prescribed for adults, but recently they have been increasingly prescribed as a treatment for enuresis in children themselves. Medicine for a trivial complaint is unlikely to be regarded by parents as potentially dangerous and practitioners should therefore warn them accordingly; if, indeed, the transient effect of these potentially dangerous drugs upon the average case of bed-wetting in childhood can be justified.

Epidemiology of acute drug intoxications: patient characteristics, drugs, and medical complications

Of 415 adult patients treated for acute drug intoxications in a university hospital emergency room, 64 (15.4%) required admission to the medical service for intensive care. A significantly larger proportion of patients over 40 years of age required hospitalization. Forty-eight of the episodes requiring hospitalization were identified as intentional drug intoxication. Women were admitted in 41 (64.0%) instances while men were admitted on 23 (36.0%) occasions. Non-barbiturate depressants, barbiturates, tranquilizers, and antidepressants were the drug classes most commonly incriminated. Almost one-half of all patients, however, had taken multiple drugs. Medical complications in these 64 patients included coma in 43 (67.2%), acute hypertension or hypotension in 21 (32.8%), and pneumonia in 16 (25%). Complications occurring less frequently were cardiac arrest in three (4.7%), anemia in two (3.2%), neuropathies, soft tissue necrosis, quadraplegia, renal failure, bullous dermatitis, and fetal death in one patient each. Two (3.2%) patients died as a result of drug ingestions. Forty per cent of patients had experienced previous episodes of acute drug intoxication.