Cardiac complications of tricyclic antidepressant therapy

The assessment of potential drug interactions with a new tricyclic antidepressant drug

1 Methods for the investigation of possible interactions with tricyclic antidepressant drugs are described. These methods have been applied to a new compound, Ciba 34276-Ba, which has been shown to have antidepressant activity. 2 In five normal volunteers tested before and during treatment with Ciba 34276-Ba, no abnormalities of resting or post-exercise electrocardiographs occurred. A three-fold reduction in tyramine-responsiveness was seen in three normal subjects studied, but no potentiation of the noradrenaline pressor effect occurred. One of six patients given Ciba 34276-Ba whilst on long-term treatment with bethanidine showed loss of blood pressure control. 3 The metabolic clearance of antipyrine was unaltered in two subjects studied, showing no evidence of induction or inhibition of hepatic microsomal oxidizing enzymes by Ciba 34276-Ba.

Quantification of tricyclic antidepressants using UPLC-MS/MS

Depression is a psychiatric condition that affects about 120 million people worldwide and can interfere with independence and productivity in essentially all aspects of daily life. Depression is also associated with risk of self-harm, and ultimately suicide. Antidepressant medications are widely used to treat symptoms of depression. While there are several classes of antidepressants, therapeutic drug management (TDM) is most common for the tricyclic antidepressants (TCAs). TDM of TCAs is important due to wide inter-individual variability in pharmacokinetics, production of active metabolites, and a high risk of drug-drug interactions. In addition, TDM of some TCAs can be used to optimize dose, wherein concentration relationships are recognized for both therapeutic response and potentially life-threatening toxicity. In many clinical scenarios, TDM of TCAs is accomplished by currently available point of care or automated immunoassays that provide a "total" TCA concentration. However, these assays may not be adequately specific to meet the needs of all clinical scenarios, and hence, chromatographic separation and quantification of individual TCA parent drugs and active metabolites that may contribute to the "total" TCA concentration is sometimes required. This chapter describes an analytical method designed to detect and/or quantify clinically significant concentrations of nine TCAs (amitriptyline, nortriptyline, imipramine, desipramine, doxepin, nordoxepin, protriptyline, clomipramine, and norclomipramine) in serum or plasma, using ultra pressure liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The sample preparation employs a rapid protein precipitation with 50:50 MeOH:acetonitrile, high speed centrifugation, and injection of 5 μL of supernatant onto the instrument, with a 5 min run-time.

Clinical features in poisonings by tricyclic antidepressants with special reference to the ECG

Clinical variables, and especially their relation to the ECG, have been studied in 153 cases of poisonings by tricyclic antidepressants (TCA). The mean age of the patients was 34 years. Amitriptyline poisoning accounted for 112 (73%) of the cases and the mean dose ingested was about 1 000 mg. Coma was present in 87 patients (57%) and on admission 40 (26%) had a systolic blood pressure (BP) below 100 mmHg. The systolic BP on admission was significantly lower (p less than 0.001) and the heart rate (HR) higher (p less than 0.001) than when the patients left the ward. Apart from an increased HR (greater than or equal to 90 beats/min), which was present in 73% of the cases, the most characteristic ECG change was a QRS prolongation (greater than or equal to 0.11 sec), this being found in 42% of the cases. About the same proportion displayed a QT prolongation and 28% had a prolonged PQ time. The mean of the QRS times was 0.11 sec. Unlike the QT time, the QRS time was not correlated to HR. Statistical analysis of the material with regard to clinical variables (dose of TCA, BP, coma duration, etc.) showed that the QRS time was closely related to the severity of poisoning. Five patients (3) died, all of whom already on admission demonstrated advanced ECG changes with arrhythmias and a mean QRS time of 0.19 sec. Excluding dibenzepine poisonings (4 cases, all fatal), the mortality rate was 0.7%. The importance of high initial preparedness for cardiac complications is pointed out, as is the value of the QRS time as a guide to the severity of poisoning.

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).

Prevalence of autonomic signs and symptoms in antimuscarinic drug poisonings

Classically described antimuscarinic poisoning signs and symptoms include mydriasis, decreased secretions, ileus, urinary retention, hyperthermia, tachycardia, and altered mental status. These features may be used clinically to assist in the diagnosis of patients with unknown poisonings. We sought to analyze the prevalence of antimuscarinic physical examination findings in evaluating patients presenting with acute poisoning from antimuscarinic agents. We conducted a retrospective, medical record review at two urban tertiary care teaching hospitals. The study population consisted of patients presenting to the Emergency Department with a diagnosis of acute poisoning secondary to medications with known antimuscarinic side effects during a 78-month period between January 1994 and July 2001. Cases were excluded for incomplete medical records or unreliable histories of ingestion, and when concomitant ethanol intoxication was present on laboratory analysis. Clinical information obtained from each patient included vital signs, pupillary size, electrocardiogram abnormalities, the presence of mucous membrane and axillary secretions, initial urine output after bladder catheterization, quality of bowel sounds, mental status changes, the occurrence of seizures and coma, need for orotracheal intubation, and time required for clinical resolution. Diagnostic and therapeutic information including laboratory tests, administration of sodium bicarbonate, and usage of physostigmine was also collected. We identified a total of 345 cases, 213 of which met inclusion criteria. Of these cases, the most common documented findings included decreased secretions in 75.1%, tachycardia in 68.1%, confusion in 49.3%, drowsiness in 48.2%, and hypoactive or absent bowel sounds in 44.6%. Combining signs and symptoms to predict this toxic syndrome was not very reliable. Tachycardia, decreased oral or axillary secretions, and mydriasis proved to be the most predictive trio of clinical signs, but were found in only 28.2% of cases. At least one of these three signs was documented in 94% of our patients. The combination of tachycardia and decreased secretions was the most common pair of findings, recorded in 55.4% of cases. We conclude that the clinical presentation of antimuscarinic syndrome is variable.

Interactions between psychotropics, anaesthetics and electroconvulsive therapy: implications for drug choice and patient management

Despite many predictions that electroconvulsive therapy (ECT) would be replaced by pharmacotherapy, ECT has remained an invaluable adjunct in the management of severe psychiatric disease. Both pharmacotherapy and ECT continue to be used extensively, and will frequently be administered concurrently. The majority of patients requiring ECT will need anaesthesia; therefore, interactions could conceivably occur between the psychotropic drugs, ECT and the anaesthetic agents utilised. In managing an anaesthetic for ECT the effects of the anaesthetic agents and other medications on seizure intensity are important determinants influencing outcome. With regard to the antidepressants, tricyclic antidepressants (TCAs) and ECT can be combined safely and beneficially. More care is required when ECT is administered in the setting of a monoamine oxidase inhibitor (MAOI), especially the older irreversible varieties and in patients recently placed on MAOI therapy. Of the anticonvulsants and mood stabilisers, lithium and ECT given concurrently add significant risk of delirium and/or organic syndromes developing. Possible concerns with valproate, carbamazepine, lamotrigine, gabapentin and topiramate are that they may inhibit seizure activity. Additionally, carbamazepine may prolong the action of suxamethonium (succinylcholine). The combination of antipsychotics and ECT is well tolerated, and may in fact be beneficial. As regards the anxiolytics, benzodiazepines have anticonvulsant properties that might interfere with the therapeutic efficacy of ECT. CNS stimulants on the other hand may prolong seizures as well as produce dysrhythmias and elevate blood pressure. Calcium channel antagonists should be used with great care to avoid significant cardiovascular depression. The anaesthesiologist should therefore remain vigilant at all times, as untoward responses during ECT might occur suddenly due to interactions between psychotropics, anaesthetic agents and/or ECT.

Management of Depression in Patients with Comorbid Cardiovascular Disease

Evidence suggests that depression commonly occurs in patients with cardiovascular disease and is associated with a poor prognosis including increased risk of cardiac mortality. Proposed pathophysiologic mechanisms include decreased heart rate variability, altered sympathetic and parasympathetic activity, increased ventricular instability, and abnormal platelet reactivity. Other proposed mechanisms involve the interference of depression with medication adherence and cardiac risk factor reduction. Despite this evidence, depression during cardiovascular disease is commonly unrecognized and inadequately treated. Tricyclic antidepressants (TCA) are efficacious for treating depression in this population but cause serious cardiac side effects and should be avoided in patients with significant cardiovascular disease. More recent studies with bupropion and the selective serotonin reuptake inhibitors (fluoxetine, paroxetine, sertraline) indicate that they are acceptable alternatives to TCAs with regard to cardiac risk in depressed patients with heart disease, although larger studies are needed to validate their safety and efficacy in this special population. There are 3 studies currently being conducted to investigate the effect of antidepressant therapy and/or psychotherapy on cardiac morbidity and mortality in post–myocardial infarction patients with depression and/or low social support. These studies will hopefully answer the long-posed question of whether appropriate treatment of depression can improve cardiac prognosis.

Efficacy of intravenous citalopram compared with oral citalopram for severe depression. Safety and efficacy data from a double-blind, double-dummy trial

BACKGROUND

Intravenous administration is often beneficial in the treatment of severely depressed patients. It is mainly the tri- and tetracyclic antidepressant drugs that can be administered intravenously. However, these drugs have a less favourable safety profile than newer antidepressants, such as the selective serotonin reuptake inhibitors (SSRIs). Citalopram is the only SSRI that is available in a formulation for infusion. This double-blind, randomised, multicentre trial was designed to compare the efficacy and tolerability of citalopram infusion (40 mg per day) and citalopram tablet (40 mg per day).

METHODS

Patients were randomised to receive either placebo tablet plus citalopram infusion (the infusion group; n=135) or citalopram tablet plus placebo infusion (the tablet group; n=119). After receiving randomised treatment for eight days, all patients entered an open treatment phase, during which they received oral citalopram 40 mg per day for five weeks.

RESULTS

Although there was no difference in Montgomery-Asberg Depression Rating Scale (MADRS) scores at the end of the randomised treatment period, by the end of the open treatment phase the reduction in MADRS scores was significantly greater in the infusion group than in the tablet group (p=0.015). The infusion group also showed superior efficacy in Clinical Global Impressions assessments. Citalopram was equally well tolerated in both treatment groups.

CONCLUSIONS

This trial confirmed the efficacy of citalopram 40 mg per day, and clearly supports the use of citalopram infusion in the treatment of severely depressed, hospitalised patients.

Cardiac disorders and antidepressant medications

Tricyclic antidepressants (TCAs) and monoamine oxidase inhibitors (MAOIs) have been associated with an increase in cardiovascular disorders, especially in depressed patients who have pre-existing cardiac disease. These disorders are less likely to occur when a therapeutic dosage is administered. Injuries because of falls are more likely in elderly depressed patients, and orthostatic hypotension occurs with the use of TCAs. Selective serotonin reuptake inhibitor (SSRI) antidepressants differ structurally and in side effects from TCAs and MAOIs. They appear to be effective for treatment of depression, and their side-effect profiles appear safer than those of earlier approved antidepressants used by depressed patients with cardiovascular disorders.

Excess risk of myocardial infarction in patients treated with antidepressant medications: association with use of tricyclic agents

PURPOSE

Several studies have found that depression and the use of antidepressant medications are associated with an increased risk of cardiovascular disease. We assessed the association between the use of antidepressant drugs and myocardial infarction, and whether that association differs between the tricyclic and selective serotonin reuptake inhibitor (SSRI) classes of medication.

PARTICIPANTS AND METHODS

We compared the experience of a cohort of 2,247 working, union health plan members who received at least one prescription for an antidepressant in an accrual period of 1991-1992 with that of 52,750 members who did not. Patients were followed for up to 4.5 years (minimum 6 months). Three antidepressant medication classes were defined: tricyclics, SSRIs, and others. The primary outcome was hospitalization or death due to myocardial infarction.

RESULTS

Adjusted for age and sex, antidepressant users had a relative risk of myocardial infarction of 2.2 (95% confidence interval [CI] 1.3 to 3.7) compared with nonusers of antidepressants. There were 16 myocardial infarctions among 1,650 users of tricyclic antidepressants, 2 among 655 SSRI users, and none among 279 users of other antidepressants. Adjusting for age, gender, baseline heart disease, diabetes, hypertension, hyperlipidemia, anxiety, and cancer, the relative risk of myocardial infarction was 2.2 (95% CI 1.2 to 3.8) in users of tricyclic agents and 0.8 (95% CI 0.2 to 3.5) in users of SSRIs, as compared with subjects who did not use antidepressants.

CONCLUSION

The association between use of tricyclic antidepressants, but not SSRIs, with an increased risk of myocardial infarction in our patients suggests that an earlier report that there is no difference in risk between the antidepressant classes, based on short-term studies, may not apply to long-term adverse cardiovascular outcomes.

Cardiac safety of citalopram: prospective trials and retrospective analyses

The selective serotonin reuptake inhibitors (SSRIs) are believed to have a more benign cardiovascular safety profile than do the tricyclic antidepressants. The effects of the SSRI citalopram on cardiac conduction and repolarization have been extensively evaluated, both in prospective studies in volunteers and patients and in retrospective evaluations of all electrocardiographic (ECG) data from all clinical trials conducted from 1978 through 1996 (a total of 40 studies). A randomized, double-blind, placebo-controlled study was conducted in healthy volunteers (N = 23) to assess intraindividual variability of the QTc interval, as well as possible changes during treatment with placebo or citalopram, and its correlation to plasma drug levels. To document any dose-related changes, ECGs were performed at baseline and at the end of study in three randomized, double-blind, placebo- or active-controlled, fixed-dose trials in adult and elderly patients (N = 1,460) with major depression and/or dementia. Finally, more than 6,000 ECGs (N = 1,789 citalopram-treated patients) collected from all clinical trials conducted from 1978 through 1996 were reassessed in a standardized manner to identify any effects of citalopram on ECG parameters. Results of both prospective and retrospective analyses showed that the only effect of citalopram on ECG findings is a small reduction in heart rate (< or = 8 beats per minute). There were no significant effects on PQ, QRS, or QTc intervals, indicating that citalopram has no effect on cardiac conduction and repolarization during short- or long-term treatment.

The role of lysosomes in the cellular distribution of thioridazine and potential drug interactions

The purpose of the present study was to investigate the contribution of lysosomal trapping to the total tissue uptake of thioridazine and to potential drug distribution interactions between thioridazine and tricyclic antidepressants (imipramine, amitriptyline) or selective serotonin reuptake inhibitors (SSRIs; fluoxetine, sertraline). The experiment was carried out on slices of various rat tissues as a system with intact lysosomes. Thioridazine and antidepressants (5 microM) were incubated separately or jointly with the tissue slices in the absence or presence of "lysosomal inhibitors," i.e., ammonium chloride or monensin. The results show that the contribution of lysosomal trapping to the total tissue uptake of thioridazine is as important as phospholipid binding. A high degree of dependence of thioridazine tissue uptake on the lysosomal trapping is the cause of substantial distributive interactions between thioridazine and the investigated antidepressants at the level of cellular distribution. Thioridazine and the antidepressants, both tricyclic and SSRIs, mutually decreased their tissue uptake. The potency of antidepressants to decrease thioridazine uptake was similar to that of lysosomal inhibitors. In general, the observed interactions between thioridazine and antidepressants occurred only in those tissues in which thioridazine showed lysosomotropism (the lungs, liver, kidneys, brain, and muscles) but were not observed in the presence of ammonium chloride. The above finding provides evidence that the interactions proceeded at the level of lysosomal trapping. In the adipose tissue and heart no lysosomal trapping of thioridazine was detected and those tissues were not the site of such an interaction. Since the organs and tissues involved in the distributive interactions constitute a major part of the organism and take up most of the total drug in the body, the interactions occurring in them may cause a substantial shift of the drugs to organs and tissues poor in lysosomes, e.g. the heart and muscles. An in vivo study into the thioridazine-imipramine interaction showed that joint administration of the drugs under study (10 mg/kg ip) increased drug concentration ratios of lysosome-poor tissue/plasma and lysosome-poor/lysosome-rich tissue. Considering serious side effects of thioridazine and tricyclic antidepressants (cardiotoxicity, anticholinergic activity), the thioridazine-antidepressant combinations studied should be approached with respect to the appropriate dose adjustment.

Issues in the perioperative care of the patient with psychiatric illness

Several topics have been reviewed pertaining to psychiatric patients requiring either surgery or ECT. Most of the morbidity unique to this group of patients in the perioperative period results from drug side effects or interactions. Complications can be minimized by familiarity with the side effects of psychotropic medication and by the discontinuation of these medications when indicated.

Effects of epinephrine and norepinephrine on hemodynamic parameters and arrhythmias during a continuous infusion of amitriptyline in rats

Epinephrine and norepinephrine were evaluated in treatment of hemodynamic compromise in amitriptyline intoxication. One hundred and one male Wistar rats were monitored hemodynamically during amitriptyline intoxication and given one of three infusion rates (0.1, 0.5 or 5.0 mg/kg/min) of either epinephrine or norepinephrine. Sixteen rats served as controls and received only glucose after intoxication. Amitriptyline intoxication lowered mean arterial pressure, heart rate, left ventricular max dP/dt, and increased left ventricular end-diastolic pressure. All doses of norepinephrine and the two higher doses of epinephrine increased mean arterial blood pressure and left ventricular max dP/dt. Heart rate increased with both drugs, more with epinephrine, but not beyond pre-intoxicated levels at any dose. Left ventricular end-diastolic pressure was unaltered by both drugs. Malignant arrhythmias appeared in 7% of all animals, whereas a progressive decline of cardiac contractility caused cardiac arrest in 36% of all animals. This suggests that myocardial depression is the aspect most likely to cause death. At intermediate doses epinephrine resulted in significantly fewer arrhythmias and lower mortality compared to norepinephrine. We conclude that epinephrine and norepinephrine each appeared effective in reversing amitriptyline-induced hemodynamic alterations. Epinephrine had fewer arrhythmogenic properties than norepinephrine and may be preferable to norepinephrine.

Drug Treatment of Depression

The major advantage of the new generation of antidepressants lies in their enhanced ability to avoid unwanted side effects, such as anticholinergic or cardiovascular toxicities, and in many cases, to reduce fatalities after overdose. Second-generation antidepressants are as effective as the first generation agents, but are more selective, enabling precise targeting of symptoms. Caution in recommending the newer antidepressants must be applied, however, because these agents possess differing side effects, and unforeseen toxicities may not appear until after several years of use. Conventional tricyclics should not be overlooked in managing the depressed patient. This article discusses the symptoms of major depression, followed by the latest information on second-generation antidepressants. It concludes by providing the pharmacist with guidelines for when to select a newer over an older agent.

The effects of imipramine, mianserin and trazodone on the chronotropic, inotropic and coronary vascular responses in the isolated perfused rat heart

1. The cardiovascular effects of the tricyclic antidepressant imipramine and two second generation antidepressants mianserin, a tetracyclic, and trazodone, a triazolopyridine derivative, were investigated in the isolated perfused rat heart. 2. Imipramine caused cardiac slowing and a negative inotropic effect at 2.5 microM after 30 min of perfusion. Conversely mianserin and trazodone had no effect on heart rate at 5 microM with inotropic state remaining above control values after 30 min of perfusion. 3. Varying effects on coronary flow, which appear to correlate well with the documented receptor actions of each drug, were demonstrated. Imipramine caused a decrease in coronary flow at 1.25 and 2.5 microM, followed by an increase at 10 microM. Mianserin decreased coronary flow at all concentrations between 1 and 20 microM. Trazodone elicited a marked elevation in coronary flow over the dose range of 2.5 to 250 microM. 4. The results in this model suggest that although the second generation agents appear to cause less cardiodepression all three agents elicit quantitatively different coronary vascular responses.

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.

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)

Cimetidine interaction with amitriptyline

The interaction of cimetidine with amitriptyline was assessed by means of amitriptyline and nortriptyline plasma concentration measurements, standing blood pressure and pulse rate, digit symbol substitution, and visual analogue scales. Cimetidine increased plasma amitriptyline concentrations and decreased plasma nortriptyline concentrations, apparently by inhibiting presystemic metabolism. The changes in blood pressure, pulse rate and digit symbol substitution correlated with changes in concentrations of amitriptyline in plasma and expected changes based on a dose ranging preliminary experiment. Changes in subjective ratings of effects correlated with changes in nortriptyline concentrations in plasma.

Clinical efficacy and electrophysiology of imipramine for ventricular tachycardia

Invasive electrophysiologic studies were performed before and during treatment with imipramine in 18 patients with inducible ventricular tachycardia (VT). All received imipramine, 50 mg twice daily for 3 days, and then 100 mg twice daily for 3 days. Imipramine increased the infranodal conduction times (HV) (from 58 +/- 7.8 to 65 +/- 10 ms) and QRS duration (from 133 +/- 21 to 153 +/- 39 ms) and significantly decreased sinus cycle length (from 875 +/- 145 to 711 +/- 116 ms) and maximal corrected sinus nodal recovery time (from 457 +/- 656 to 380 +/- 603 ms). The Wenckebach cycle length tended to decrease and the QT interval to increase, but these changes were not statistically significant. Atrial and ventricular refractory periods, atrioventricular nodal conduction times and induced VT cycle length did not change significantly. Imipramine prevented induction of VT in 2 patients, and VT was more difficult to induce in 1 patient. These 3 patients received chronic imipramine therapy. The 2 patients in whom no VT could be induced while taking imipramine have had no recurrence of arrhythmia at 6 and 12 months of follow-up. The third patient died suddenly 4 months after discharge from the hospital. One patient had worsening of arrhythmias while taking imipramine and 61% had minor adverse effects. The mean combined plasma imipramine and desmethylimipramine concentration at the time of the repeat electrophysiologic study was 227 +/- 114 ng/ml. Imipramine is effective against VT in some patients; however, like other type I antiarrhythmic drugs, the rate of efficacy is low.

[Acute voluntary carpipramine poisoning with ventricular tachycardia]

A case of carpipramine overdose is reported. The patient was admitted with ventricular tachycardia 4 h after taking 2.40 g of the drug. This disappeared at the sixth hour. In overdoses with other tricyclics, ventricular tachycardia was successfully treated within 30 min of starting a sodium lactate perfusion. In the case presented, reversal of the ventricular tachycardia coincided with the half-life of the drug; the effects of perfusing 1000 ml sodium lactate over 2 h seemed doubtful. This sodium resistance may be related to a relative hypokalemia (3.4 mmol X 1(-1) ). The use of sodium lactate for the treatment of overdoses with drugs with short-half lives appeared questionable.

Cardiac effects of antidepressant drugs. A comparison of the tricyclic antidepressants and fluvoxamine

1 The cardiovascular effects of the tricyclic antidepressants (TCAs) are reviewed and compared with those of fluvoxamine, a new 5-hydroxytryptamine (5-HT) re-uptake inhibitor. 2 The TCAs have important effects on the heart, related to their anticholinergic and quinidine-like properties. The major side effects in therapeutic dosage include heart rate increase, postural hypotension and slight prolongation of the intraventricular conduction time and QT interval. In toxic dosage (or normal dosage in patients with severe heart disease) both advanced heart block and ventricular arrhythmias can occur, together with clinically important loss of myocardial contractile force. 3 Fluvoxamine has no effects on the heart except for a statistically (but not clinically) significant slowing of the heart rate.

Immediate effects of physostigmine on amitryptyline-induced QRS prolongation

Prior studies have suggested that physostigmine may be useful in reversing QRS prolongation due to amitriptyline toxicity. To investigate this question, we devised a pharmacologic model in rabbits utilizing an initial intravenous bolus of amitriptyline (4-6 mg) followed by a constant amitriptyline infusion (0.2-0.4 mg/min) empirically titered to maintain the QRS at 50% or more of control value for at least 5 min. Intravenous physostigmine (2 mg) sufficient to produce muscle fasciculations and significant (P less than 0.01) slowing of sinus rate was then administered to six animals. No significant change in QRS duration was noted at 1, 3, and 5 min intervals following physostigmine. Although no immediate antidotal effect of physostigmine on amitriptyline-induced QRS prolongation could be demonstrated, these results do not exclude a possible interaction between the membrane effects of the tricyclic antidepressants (and related agents) and the vagal branch of the autonomic nervous system.

Cardiocirculatory effects of Ro 11-2465, a selective 5-HT (serotonin) uptake inhibitor, in healthy volunteers

The imipramine derivative Ro 11-2465, a potent, selective 5-HT (serotonin) uptake inhibitor, is being developed as an antidepressant agent. The effects of Ro 11-2465 on heart rate, blood pressure, electrocardiogram and systolic time intervals were assessed in nine normotensive volunteers. Ro 11-2465 1 and 2 mg and a placebo were given in a single blind, cross over design study. The placebo did not induce any significant changes. With Ro 11-2465, the ECG-intervals (P, PQ, QRS, QTc) did not change, the blood pressure increased 3-6 h after administration of either dose, and the heart rate was increased 4-6 h after the 2 mg dose. There was also evidence of increased ventricular automaticity in one subject. the total electromechanical systole (QS2-index) was significantly shortened 4-8 h after administration of 2 mg, whereas neither 1 mg the dose nor the placebo had any such effect. This finding suggests the presence of a positive inotropic effect, which is probably due to a stimulatory effect of serotonin, and is not mediated by an adrenergic mechanism. The findings suggest that Ro 11-2465, as a potential new tricyclic antidepressant, might have favourable cardiocirulatory dose effects, particularly in patients with pre-existing heart disease.

Effects of antidepressants on cardiac function

Most antidepressants may affect the cardiovascular system adversely although their mode of action in causing these complications differs. They affect the cardiovascular system directly or through drug interactions. They may affect blood pressure, the inotropic state of the heart and cardiac conduction. The causes of these complications are discussed with relevance to the known action of these agents. Although serious cardiovascular complications do not occur frequently at therapeutic dosage, a knowledge of these abnormalities is essential for safe prescribing. After overdose many of these agents may prove lethal.

Safety data on zimelidine hydrochloride following an overdose

Zimelidine, a new antidepressant, has proved to be a potent and selective inhibitor of 5-HT uptake into central 5-HT neurons. Due to its structural differences from the tricyclic antidepressants, it has also been suggested that it may have a different pharmacological profile, and be devoid of anticholinergic and noradrenaline potentiating properties. During the treatment with zimelidine hydrochloride, as a part of an open trial, one of our patients, a 38-year-old chronically depressed woman, overdosed herself with more than 10 times the actual therapeutic dose of zimelidine with no undesirable side effects. Previous studies have indicated that zimelidine in comparison with imipramine and chlorimipramine has no, or at most, a slight effect on peripheral adrenergic neurons, and has less pronounced anticholinergic properties than imipramine. The findings of our overdose case provide some support for these findings.

Comparison of the cardiovascular effects of amitriptyline and zimelidine using thoracic impedance cardiography

Twelve depressed patients were allocated to amitriptyline (7 days 75 mg nocte, increasing to 150 mg nocte) or zimelidine (100 mg nocte increasing to 200 mg nocte) in a randomized double-blind design. Cardiovascular assessment was made at pre-drug, 7 and 14 days using thoracic impedance cardiography, a non-invasive technique for measurement of both cardiac output (CO) and systolic time intervals. Neither drug significantly changed systolic time intervals. Amitriptyline 75 mg significantly reduced stroke volume (SV) (sitting P less than 0.02, standing P less than 0.01) with a similar trend at 150 mg. Zimelidine tended to increase SV. Heart rate (HR) was increased by amitriptyline 75 mg (P less than 0.02) but zimelidine induced no consistent changes in HR. Amitriptyline 75 mg in the standing data reduced CO (P less than 0.005). In contrast zimelidine 100 mg increased sitting CO (P less than 0.05) and this trend was seen at 200 mg in both sitting and standing data. The results suggest that zimelidine has low cardiotoxicity and may have a role in the treatment of depressed patients with cardiovascular disease.

Bilateral symmetrical brain lesions in tricyclic antidepressant overdosage

The cerebral pathology in a case of tricyclic antidepressant overdose by amitriptyline is described. A review of the literature of similar cases is summarized. The relation of the cerebral lesions to the development of a hypertensive episode possibly induced by amitriptyline is discussed.

Cardiovascular side effects of phenothiazines and tricyclic antidepressants. A review with precautionary measures

A well-documented association exists between the phenothiazines and the tricyclic antidepressants and such alarming side effects as cardiac arrhythmias, ECG changes, and even sudden death. Most disturbing is the fact that major and possibly fatal arrhythmias can occur in young adults without antecedent heart disease who are receiving therapeutic dosages of these psychotropic drugs (especially thioridazine). Further study of the cardiovascular side effects of psychotropic drugs is needed to clarify the association. In the meantime, it is mandatory that physicians individualize treatment programs that include these drugs and carefully monitor patient response.

The electrocardiographic and antiarrhythmic effects of imipramine hydrochloride at therapeutic plasma concentrations

The electrocardiographic effects of imipramine hydrochloride at therapeutic plasma concentrations were determined in 44 depressed patients during a 6-week clinical outcome study of depression. During each week of the protocol, i.e., 2 weeks of control and 4 weeks of drug treatment, a standard 12-lead ECG, high-speed, high-fidelity ECG tracings, and a 24-hour continuous ECG recording were obtained. PR, QRS, and QTc intervals, T-wave amplitude, heart rate and frequency of ventricular premature depolarizations (VPDs) were measured. The plasma concentration of imipramine and desmethylimipramine was measured three times a week. Imipramine prolonged the PR (p less than 0.001), QRS (p less than 0.001) and QTc (p less than 0.001) intervals, increased the heart rate (p less than 0.001) and lowered T-wave amplitude (p less than 0.05) during the 4 weeks of treatment. No patient developed high-grade atrioventricular block or severe intraventricular conduction abnormalities. In addition, imipramine had a potent antiarrhythmic action in patients who were recovering from depression. Ten of 11 patients who had more than 10 VPDs/hour had 90% or greater arrhythmia suppression during antidepressant treatment with imipramine at plasma concentrations ranging from 100--302 ng/ml.

Anesthetic considerations in surgery for gastrointestinal disease

We have attempted to present a brief overview of current considerations in anesthesia for surgery of gastrointestinal disease as practiced at our institution. Many considerations remain unexplored owing to limitations of space. We have deliberately concentrated upon antecedent and concurrent therapy encountered in the treatment of the surgical patient. The potent drugs introduced in the past decade have produced infinite potential for drug interactions--some serious, some not so serious, and some which are desirable. We hope we have generated further reader interest in this mushrooming problem of modern medicine confronting the anesthesiologist and surgeon in the perioperative period.

Interaction studies between three antidepressant drugs (chlorimipramine, imipramine and zimelidine) and noradrenaline, tyramine and vagal stimulation on the heart rate and blood pressure in dogs

Anaesthetized Beagle dogs were given increasing intravenous doses of imipramine, chlorimipramine or zimelidine. At each dose interval the interference of the drug administered with the effects on blood pressure and heart rate of vagal stimulation, NA injection and tyramine injection was investigated. Also, the in vitro uptake of 5-HT into platelets after in vivo administration to unanaesthetized dogs of 5 mg chlorimipramine or 5 mg zimelidine was studied. Chlorimipramine and zimelidine were found to be about equipotent as regards 5 HT-uptake into platelets after in vivo administration. Imipramine and chlorimipramine potentiated the effects of NA after the 2 mg/kg dose. Imipramine but not chlorimipramine interfered with the effects of tyramine after the 4 mg/kg dose. Zimelidine did not interfere with either NA or tyramine at any dose level studied (maximal cumulative dose 62 mg/kg). The effect of vagal stimulation was significantly inhibited after 8 mg/kg (cumulative dose 14 mg/kg) of imipramine and 16 mg/kg (cumulative dose 30 mg/kg) of chlorimipramine and zimelidine, respectively. It is concluded that zimelidine in comparison with imipramine and chlorimipramine has no or at most a slight effect on peripheral adrenergic neurones. It has less pronounced anticholinergic properties than imipramine but is about equipotent to chlorimipramine in this respect.

Trazodone and imipramine: comparative effects on canine cardiac conduction

Lead II EKG and His bundle electrograms were recorded in closed-chest pentobarbital-anesthetized dogs. Trazodone, a structurally distinct, new antidepressant agent, had no effect on His--Purkinje (HV interval) or intraventricular (HS interval) conduction following intravenous injection at graded doses between 1 and 30 mg/kg. In contrast, the tricyclic psychotropic agent imipramine (0.5--5 mg/kg) significantly slowed impulse conduction as indicated by increases in both the HV and HS intervals. Imipramine (5 mg/kg) also slowed impulse transmission across the atrium (PA interval). These responses to imipramine were associated with a concurrent prolongation of both the PR interval and QRS duration. In the anesthetized dog, trazodone administration promoted no evidence of heart block or sign of rhythm disturbances other than slowing in normal sinus rhythm.

Electrophysiological actions of chlorimipramine on guinea-pig ventricular fibres

Chlorimipramine (CMI, 1 x 10(-5)M to 7 X 10(-5)M) decreased the amplitude, overshoot and rate of rise of ventricular action potentials and abolished the Ca-mediated action potentials elicited in guinea-pig papillary muscles. These results indicates that CMI inhibits the rise in sodium and calcium conductances during the cardiac action potential.