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.

Combining single patient (N-of-1) trials to estimate population treatment effects and to evaluate individual patient responses to treatment

When treating individual patients, physicians may face difficulties using the evidence from center-based randomized control trials (RCTs) due to limitations in these studies generalizability. Therefore, they often perform their own "informal" tests of treatment effectiveness. Single patient ("N-of-1") trials provide a structured design for more rigorous assessment of medical treatments of chronic diseases, but are applied only to the index patient. We present a hierarchical Bayesian random effects model to combine N-of-1 studies to obtain an estimate of treatment effectiveness for the population and to use this population information to aid in the evaluation of an individual patient's trial results. The model's treatment effect estimates are adjustments between the population estimate and the individual's observed results. This adjustment is based upon the within-patient and between-patient heterogeneity. We demonstrate this patient-focused method using published data from 23 N-of-1 trial results comparing amitriptyline and placebo for the treatment of fibromyalgia.

The role of alcohol and drugs in triggering criminal violence: a case-crossover study*

AIMS

To investigate the triggering effects of alcohol, illegal substances and major classes of prescribed psychotropic drugs on criminal violence.

DESIGN

A case-crossover design, using each subject as its own control.

SETTING AND PARTICIPANTS

A consecutive sample of 133 violent offenders was recruited from a forensic psychiatric evaluation unit and a national prison evaluation unit in Sweden during 2002-03. Measurements Offenders were assessed with structured interviews. Risk estimates were based on hazard periods of 24 hours. We used standard Mantel-Haenszel methods for statistical analyses.

FINDINGS

A 13.2-fold increase of risk of violence [95% confidence interval (CI): 8.2-21.2] was found within 24 hours of alcohol consumption. This increase in violence risk was similar among individuals combining alcohol with benzodiazepines [Relative risk (RR) = 13.2, 95% CI: 4.9-35.3]. Use of benzodiazepines alone in regular doses (RR = 0.4, 95% CI: 0.2-0.5) or antidepressants [selective serotonin reuptake inhibitors (SSRIs) or tricyclics] (RR = 0.4, 95% CI: 0.3-0.8) was associated with a lowered risk for violence.

CONCLUSIONS

This study confirmed that alcohol is a strong trigger of criminal violence. Benzodiazepines in combination with alcohol caused no further increase of violence risk. Benzodiazepines in regular doses and antidepressants may inhibit violence, but further studies are needed to verify causality. The case-crossover method can contribute to research on the proximal causes of criminal violence.

Hypothalamus-pituitary-adrenal modifications consequent to chronic stress exposure in an experimental model of depression in rats

The modifications in the hypothalamus-pituitary-adrenal (HPA) axis function induced by repeated unavoidable stress exposure, according to a standardized procedure used for inducing an experimental model of depression, were studied. Rats exposed to this procedure show hyporeactivity to both pleasurable and aversive stimuli and this condition is antagonized by the repeated administration of classical antidepressant drugs. We also studied whether imipramine administration during stress exposure would interfere with the possible modifications in the HPA axis. Rats were exposed to a 4-week stress procedure with and without imipramine treatment and then tested for escape, as compared with non-stressed control animals. Twenty-four hours later all rats were bled through a tail nick for plasma corticosterone measurement before and after dexamethasone (10 microg/kg) or corticotropin-releasing hormone (CRH, 1 microg/kg) administration. Rats were then killed, adrenals and thymus weighed, brain areas dissected out and frozen for glucocorticoid receptors (GRs) and corticotropin-releasing hormone receptor 1 (CRHR1) immunoblotting and for the assessment of hypothalamic corticotropin-releasing hormone levels.

RESULTS

Rats exposed to a 4-week unavoidable stress showed escape deficit and their basal plasma corticosterone levels were higher than those of control animals. Moreover, they had decreased response to dexamethasone administration, adrenal hypertrophy, and decreased GR expression in the hippocampus, hypothalamus, medial prefrontal cortex and pituitary. No significant modifications in CRHR1 expression were observed in the pituitary nor in different discrete brain areas. CRH levels in the hypothalamus and the plasma corticosterone response to CRH administration were found to be higher in stressed rats than in controls. Imipramine treatment offset all the behavioral and neurochemical stress-induced modifications. In conclusion, the present results strengthen the assumption that the escape/avoidance behavioral deficit induced by inescapable stress exposure is accompanied by steadily increased HPA activity, and that imipramine effect is strongly related to a normalization of HPA axis activity.

Antidepressant effects of nicotine and fluoxetine in an animal model of depression induced by neonatal treatment with clomipramine

The association between smoking and depression has been widely investigated. Most of these reports suggest that nicotine (NIC) may act as an antidepressant. To examine the suggested antidepressant effect of nicotine and its possible interaction with the serotonergic system, we assessed the effect of nicotine and fluoxetine (FLX) in an animal model of depression induced by neonatal treatment with clomipramine (CLI) and submitted to the forced swim test (FST). Results corroborated that CLI-treated rats displayed higher levels of immobility. After the administration of nicotine (0.4 mg/kg sc) acutely (1 day), subchonically (7 days), and chronically (14 days), CLI-treated rats significantly reduced the immobility and increased swimming without affecting climbing. These effects were similar to the effects induced for subchronic and chronic administration of the antidepressant fluoxetine (5 mg/kg sc), a selective serotonin re-uptake inhibitor. However, fluoxetine failed to affect immobility when it was administered acutely. No synergism was observed when both drugs were administered simultaneously. The present results further corroborate the antidepressant action of nicotine and fluoxetine. The increase of swimming during the FST has been linked to an increase of serotonergic activity. Thus, it could be possible that the antidepressant action of nicotine is mediated by the serotonergic system.

Evaluating the Validity of an Instrumental Variable Study of Neuroleptics

BACKGROUND

Postmarketing studies of prescription drugs are challenging because prognostic variables that determine treatment choices are often unmeasured. In this setting, instrumental variable (IV) methods that exploit differences in prescribing patterns between physicians may be used to estimate treatment effects; however, IV methods require strong assumptions to yield consistent estimates. We sought to explore the validity of physician-level IV in a comparative study of short-term mortality risk among elderly users of conventional versus atypical antipsychotic medications (APM).

METHODS

We studied a cohort of patients initiating APMs in Pennsylvania who were eligible for Medicare and a state-funded pharmaceutical benefit plan. The IV was defined as the type of the APM prescription written by each physician before the index prescription. To evaluate whether the IV was related to other therapeutic decisions that could affect mortality, we explored the association between the instrument and 2 types of potentially hazardous coprescriptions: a tricyclic antidepressant (TCA) not recommended for use in the elderly or a long-acting benzodiazepine. To insure that the IV analysis was not biased by case-mix differences between physicians, we examined the associations between the observed patient characteristics and the IV.

RESULTS

The cohort consisted of 15,389 new users of APMs. Our multivariable model indicated that physicians who had most recently prescribed a conventional APM were not significantly more or less likely to coprescribe a potentially hazardous TCA [odds ratio (OR), 0.78; 95% confidence interval (CI), 0.58-1.02] but were less likely to prescribe a long-acting benzodiazepine (OR, 0.57; 95% CI, 0.45-0.72) with their current APM prescription. The association between long-acting benzodiazepine prescribing and APM preference was no longer significant when the analysis was restricted to primary care physicians (OR, 0.84; 95% CI, 0.62-1.15). Multivariable regression indicated that important medical comorbidities (eg, cancer, hypertension, stroke) were unrelated to the IV.

CONCLUSIONS

The previous APM prescription written by the physician was unassociated with major medical comorbidities in the current patient, suggesting that the IV estimates were not biased by case-mix differences between physicians. However, we did find that the IV was associated with the use of long-acting benzodiazepines. This association disappeared when the study was restricted to the patients treated by primary care physicians. Our study illustrates how internal validation approaches may be used to improve the design of quasi-experimental studies.

Level of consciousness as a predictor of complications following tricyclic overdose

In order to determine whether patients at low risk for complications following tricyclic antidepressant (TCA) overdose can be identified, we analyzed the records of all admissions for TCA overdose from 1975 to 1985. Of the 92 patients reviewed, 37 had serious complications including hypoventilation, loss of protective airway reflexes, seizures, hypotension, hemodynamically significant arrhythmias, or death. Patients with complications had increased heart rate, depressed level of consciousness, depressed Glasgow Coma Scale, and prolonged QRS interval, as compared to patients without complications. All 37 patients with serious complications required intubation in the emergency department. A Glasgow Coma Scale of less than 8 was the most sensitive predictor of serious complications (sensitivity = .86; specificity = .89). This was significantly better than the QRS interval (QRS greater than or equal to 100 msec; sensitivity = 59; specificity = .76). We conclude that level of consciousness is a better predictor of risk of complications and need for ICU admission than the QRS interval. Patients who are responsive to verbal stimuli on leaving the ED are at very low risk of developing complications.

A lipid nanoparticle platform for mRNA delivery through repurposing of cationic amphiphilic drugs

Since the recent clinical approval of siRNA-based drugs and COVID-19 mRNA vaccines, the potential of RNA therapeutics for patient healthcare has become widely accepted. Lipid nanoparticles (LNPs) are currently the most advanced nanocarriers for RNA packaging and delivery. Nevertheless, the intracellular delivery efficiency of state-of-the-art LNPs remains relatively low and safety and immunogenicity concerns with synthetic lipid components persist, altogether rationalizing the exploration of alternative LNP compositions. In addition, there is an interest in exploiting LNP technology for simultaneous encapsulation of small molecule drugs and RNA in a single nanocarrier. Here, we describe how well-known tricyclic cationic amphiphilic drugs (CADs) can be repurposed as both structural and functional components of lipid-based NPs for mRNA formulation, further referred to as CADosomes. We demonstrate that selected CADs, such as tricyclic antidepressants and antihistamines, self-assemble with the widely-used helper lipid DOPE to form cationic lipid vesicles for subsequent mRNA complexation and delivery, without the need for prior lipophilic derivatization. Selected CADosomes enabled efficient mRNA delivery in various in vitro cell models, including easy-to-transfect cancer cells (e.g. human cervical carcinoma HeLa cell line) as well as hard-to-transfect primary cells (e.g. primary bovine corneal epithelial cells), outperforming commercially available cationic liposomes and state-of-the-art LNPs. In addition, using the antidepressant nortriptyline as a model compound, we show that CADs can maintain their pharmacological activity upon CADosome incorporation. Furthermore, in vivo proof-of-concept was obtained, demonstrating CADosome-mediated mRNA delivery in the corneal epithelial cells of rabbit eyes, which could pave the way for future applications in ophthalmology. Based on our results, the co-formulation of CADs, helper lipids and mRNA into lipid-based nanocarriers is proposed as a versatile and straightforward approach for the rational development of drug combination therapies.

Drug abuse patterns of patients on methadone treatment in New York City

Urine specimens from methadone treatment clinics were screened for various abused drugs between 1974-1979 by thin-layer chromatography (TLC) and immunoassay techniques (IAT). A comparison of the relative incidence of drugs abused reveals that IAT are more sensitive and detect far greater number of subjects abusing drugs than TLC. The results also show a significant abuse of heroin and cocaine during the period studied and a variation of the incidence of other drugs used during the same period. While these patients did not receive benzodiazepenes and tricyclic antidepressants by prescription, their abuse alone and in combination with each other was also found to be widespread. Low levels of PCP and/or its analogs were found in 1978 and 1979. The frequent finding of low levels of PCP in combination with other drugs indicates the availability of this hallucinogen and point to its use in combination with other illicit drugs such as cocaine, amphetamine, and heroin. The suggestion is made that more sensitive analytical methods for drugs screening be utilized in methadone monitoring programs, and that other classes of drugs be added than are currently required.

QRS interval in tricyclic antidepressant overdosage: inaccuracy as a toxicity indicator in emergency settings

Emergency department treatment and disposition of tricyclic antidepressant (TCA)-overdose patients remains a common and difficult problem. Various clinical findings have been proposed as toxicity indicators. To study the performance of QRS duration as a predictor of toxicity in our patient population, we retrospectively reviewed the cases of all patients presenting to our ED with TCA overdosage. The charts of 102 patients with quantitative or qualitative laboratory confirmation of TCA ingestion were reviewed for ED findings and hospital course with specific attention to the occurrence of ventricular arrhythmias (VAs) or seizures. The ED ECG revealed that 57 patients had a maximal 12-lead ECG QRS interval duration (QRS) of less than .10 seconds (Group 1). The remaining 45 patients had QRS greater than or equal to .10 seconds (Group 2). Three patients (5%) in Group 1 and three (6%) in Group 2 experienced VAs. Four patients (7%) in Group 1 and five (11%) in Group 2 experienced seizures. There was no significant difference in the rate of occurrence of VAs or seizures between the two groups. Of note was the fact that five of eight VAs and nine of 11 seizures occurred in the ED setting. We conclude that determination of QRS duration is not an accurate indicator of VA or seizure risk for all TCA-overdose populations. In particular, risk of toxic events during the emergency phase of TCA overdose does not appear to be indicated by evaluation of the QRS duration in the ED.

Complications after overdose with tricyclic antidepressants

We reviewed 72 consecutive cases of tricyclic antidepressant (TCA) overdose (OD) admitted from the emergency ward (EW) to the ICU between 1977 and 1982. Most patients were seriously ill before ICU admission: 70% were comatose; 68% were intubated, including 61% in need of mechanical ventilation; and 30% were hypothermic. One patient died after ICU admission. ECG abnormalities were present in 37 (51%) patients in the EW. These abnormalities were associated with higher TCA plasma levels, but not with either acidosis or hypoxemia. Of 14 patients without ECG abnormalities or the need for intubation in the EW, none developed new ECG abnormalities or required ventilatory support. No patient had a late complication after transfer from the ICU, after a mean stay of 2.1 days. Late, unexpected complications in TCA OD are very rare. Our study suggests that TCA OD patients who do not have an abnormal ECG and do not require ventilatory support at the time of initial evaluation may not need ICU admission simply for intensive observation.

Chronic amitriptyline treatment induces hippocampal NGFI-A, glucocorticoid receptor and mineralocorticoid receptor mRNA expression in rats

Adult male rats were treated with the antidepressant drug amitriptyline for 21 days and the expression of specific transcription factors was examined. NGFI-A mRNA expression was increased in the hippocampus and in the cerebral cortex. MR mRNA was increased in the hippocampus while GR mRNA was increased in selective hippocampal regions. There was no change in the NGFI-B mRNA expression. Thus, NGFI-A may be a mediator of plasticity-related phenomena induced by antidepressant drugs.

A population-based assessment of the potential interaction between serotonin-specific reuptake inhibitors and digoxin

AIM

In vitro evidence suggests that some serotonin-specific reuptake inhibitors (SSRIs) inhibit P-glycoprotein, a multidrug efflux pump responsible for the elimination of several drugs including digoxin. We sought to determine if some SSRIs cause digoxin toxicity in the clinical setting.

METHODS

Population-based nested case-control study set in Ontario, Canada from 1994 to 2001. We studied all patients 66 years or older treated with digoxin. Prescription and hospital admission records were analysed to determine the relationship between the initiation of SSRI therapy and hospital admission for digoxin toxicity in the subsequent 30 days.

RESULTS

Among 245 305 older patients treated with digoxin, we identified 3144 cases of digoxin toxicity. After adjusting for potential confounders, we observed an increased risk of digoxin toxicity following initiation of paroxetine [odds ratio (OR) 2.8; 95% confidence interval (CI) 1.6, 4.7], fluoxetine (OR 2.9; 95% CI 1.5, 5.4), sertraline (OR 3.0; 95% CI 1.9, 4.7), and fluvoxamine (OR 3.0; 95% CI 1.5, 5.7). However, an elevated risk was also seen with tricyclic antidepressants (OR 1.5; 95% CI 1.0, 2.4) and benzodiazepines (OR 2.1; 95% CI 1.7, 2.5), drugs classes having no known pharmacokinetic interaction with digoxin. There was no statistical difference in the risk of digoxin toxicity among any of the agents tested.

CONCLUSIONS

We found no major discrepancy in the risk of digoxin toxicity after initiation of various SSRI antidepressants, suggesting that the inhibition of P-glycoprotein by sertraline and paroxetine observed in vitro is unlikely to be of major clinical significance.

Skeletal muscle necrosis following membrane-active drugs plus serotonin

Administration of imipramine plus serotonin (5-HT) to rats has been proposed as an animal model of Duchenne muscular dystrophy. We studied the skeletal muscle necrosis produced in male rats given 5-HT after pretreatment with imipramine, other tricyclic antidepressants, or antihistamines, which like the tricyclic antidepressants, can block neuronal reuptake of 5-HT. Following one of these agents plus 5-HT, 20 mg/kg subcutaneously (s.c.), necrosis was more severe in the soleus muscle than the quadriceps. There was no significant difference in the incidence of necrosis in the soleus and quadriceps muscles following one of these agents plus 5-HT, 100 mg/kg, intraperitoneally (i.p.). After one of these agents plus 5-HT i.p., but not 5-HT s.c., extensive necrosis was significantly more frequent and severe in the quadriceps muscle than after 5-HT s.c. Chlorpheniramine (CP) plus 5-HT, 2.5 mg/kg intravenously, produced less muscle necrosis than CP plus 5-HT s.c. or i.p. The necrosis produced by CP plus 5-HT s.c. was comparable ipsilateral and contralateral to the injection site. The necrosis following CP plus 5-HT i.p. was maximal at 24 hr and remained fairly constant until 5 days. Regeneration was prominent by 7 days. The muscle necrosis produced by CP plus 5-HT is blocked by some 5-HT blockers, e.g., methiotepin and methysergide. It is also partially blocked by denervation. The capacity of tricyclic antidepressants and antihistamines to block neuronal 5-HT reuptake tended to be negatively correlated with the capacity to potentiate the muscle necrosis they produced with 5-HT, which suggests that blockade of 5-HT uptake is not the mechanism of the pathology produced by the combined treatment. The tricyclic antidepressants and the antihistamines are "membrane stabilizers-labilizers". Other drugs which are "membrane stabilizers-labilizers" such as trihexyphenidyl and procaine also promoted skeletal muscle necrosis when given prior to 5-HT. It is proposed that the effects of imipramine plus 5-HT on skeletal muscle are not due to the blockade of neuronal uptake of 5-HT and subsequent vascular-induced ischemia, but reflect direct toxic effects of these agents on skeletal muscle.

Comparison of the pharmacological actions of desmethylclomipramine and clomipramine

This research compares the effects, in mice and rats, of desmethylclomipramine (DCLOM) and clomipramine (CLOM). DCLOM antagonized the hypothermia induced in mice by reserpine or apomorphine to a much greater extent than CLOM. Reserpine ptosis in mice was depressed by DCLOM only. Similarly, only DCLOM was effective in the behavioral despair test in rats. DCLOM increased the 5-hydroxytryptamine (5-HT) pressor effect in pithed rats, but to a lesser extent than CLOM by several factors. Only DCLOM increased the noradrenaline (NA) pressor effect. The depletion of NA induced by 6-hydroxydopamine was depressed by DCLOM only. The 5-HT depletion induced by p-chloromethamphetamine was antagonized only by CLOM. The results obtained show that the noradrenergic mechanism is of prime importance in the action of DCLOM and of much more importance than in the action of CLOM.

Pharmacotherapy of post-traumatic stress disorder

Post-traumatic stress disorder (PTSD) is a prevalent psychiatric disorder that may result in significant social and occupational debilitation unless symptoms are recognized and treated appropriately. Considerable research effort has been devoted over the last 20 years to developing effective pharmacological treatments for this illness. At this time, the bulk of the agents investigated include antidepressants, anticonvulsants, atypical antipsychotics, benzodiazepines, and antiadrenergic agents. Herein, we review the existing evidence base for these different classes of psychotropics in PTSD. Emphasis is placed on discussion of evidence stemming from randomized placebo-controlled clinical trials wherever possible. A brief description of novel agents that have shown initial promise for PTSD treatment is also provided.

Tricyclic antidepressant drugs as antagonists of muscarinic receptors in sympathetic ganglia

Close arterial injection of McN-A-343 into the superior cervical ganglion of the cat resulted in contractions of the nictitating membrane. The ganglionic effects of McN-A-343 but not those of DMPP were antagonized in a dose-related manner by 2-10 mug of desipramine, imipramine, chlorimpramine, iprindole and viloxazine. No correlation was found between the dose of each drug which blocked the effects of McN-A-343 and that required to potentiate the responses of the nictitating membrane to intra-arterial administration of noradrenaline. It is concluded that clinically effective antidepressant agents can block muscarinic receptors in neural tissue, even if they do not do so in smooth muscle and gland cells.

Mirtazapine-induced hyponatremia in an elderly hospice patient

BACKGROUND

Mirtazapine, which enhances central noradrenergic and serotonergic activity, is a commonly prescribed drug for mood disorders in elderly patients due to the low incidence of adverse effects. A heterocyclic antidepressant, mirtazapine has pharmacodynamics similar to selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants. Nevertheless, geriatric patients in general are more prone to experience adverse drug effects.

OBJECTIVE

To report a case of hyponatremia in an elderly hospice patient associated with mirtazapine use.

CASE SUMMARY

A 72-year-old Latino male with stage IV colon cancer entered into hospice care and was treated for major depressive disorder with mirtazapine. On day 6 of treatment, he was somnolent and confused. He was found to have severe hyponatremia (serum sodium of 116 mmol/L) without any immediately identifiable physiologic cause. His previous sodium levels were within normal limits over a 6-month period including when mirtazapine was started. Upon discontinuation of mirtazapine, the patient's mental status improved, and his sodium level returned to normal.

DISCUSSION

Hyponatremia resulting from antidepressant use, particularly SSRIs, is rare in the general population, but in the elderly population the incidence increases because of multiple factors. There are few reports in the literature regarding hyponatremia induced by mirtazapine.

CONCLUSIONS

The benefit of treating mood disorders at the end of life outweighs the risks of untreated depression. Hyponatremia, although an uncommon adverse effect of mirtazapine therapy, should be considered in the elderly patient with altered mental status or delirium who has recently initiated mirtazapine therapy.

Feasibility and effectiveness of treatments for depression in elderly medical inpatients: a systematic review

To determine the feasibility and effectiveness of treatments for depressed elderly medical inpatients, MEDLINE was searched for potentially relevant articles published from January 1987 to August 1997, using the keywords "depression or depressive disorder" (exploded) and "aged." The bibliographies of relevant articles were searched for additional references. Fifteen reports met the following inclusion criteria: (a) published in English or French; (b) minimum age criterion of 55 and over or mean age 65 and over; (c) subjects admitted to the medical service of an acute care hospital; (d) used accepted criteria for depression; (e) examined treatment(s) for depression; and (f) reported outcomes as a depression diagnosis and/or symptom level. Information was abstracted independently from each article by two reviewers, tabulated, and compared. The limited evidence suggests contraindications to treatment in 38% to 87% of subjects who received a heterocyclic antidepressant compared to 4% of subjects who received the selective serotonin reuptake inhibitor (SSRI) fluoxetine; rates of discontinuation and study completion were similar for heterocyclics, the SSRIs, and psychostimulants. All of the treatments (including social support/psychotherapy) appeared to be at least modestly effective in the short term.

In vitro interaction of neuroleptics and tricylic antidepressants with coffee, tea, and gallotannic acid

The in vitro interaction of selected drugs with coffee, tea, gallic acid, and gallotannic acid was examined by mixing solutions of drug with each of these four preparations. Results of these experiments indicate that significant precipitation occurs for a variety of agents, including several phenothiazines, amitriptyline, haloperidol, imipramine, and loxapine. The strong complex which is formed between these drugs and tannins is probably the basis of the interaction of these drugs with coffee and tea. Although precipitates did occur with a number of neuroleptics, two members of this drug class, thiothixene and molindone, failed to interact with the solutions used.