Epidemiology, symptoms, and treatment characteristics of hyponatremic psychiatric inpatients

An Instant Relationship Between Hyponatremia, Geriatric Syndromes, and Drugs in Older Adults: A Cross-Sectional Analysis from a Single Geriatric Clinic

Background: Hyponatremia is a common electrolyte disorder in older adults that can lead to poor clinical outcomes and increased mortality. This study aims to evaluate the interrelationship between hyponatremia and geriatric syndromes and drugs in older adults. Methods: This study included 1100 elderly patients admitted to a geriatric clinic. Patient records were used to obtain demographic information, comorbidities, geriatric syndromes, medications, laboratory results, and comprehensive geriatric assessment parameters. Results: The prevalence of hyponatremia was 23.9% in this study (mean age ± SD was 75.59 ± 8.13 years). The frequency of polypharmacy, dementia, falls, malnutrition and risk of malnutrition, frailty, probable sarcopenia, hypertension, cerebrovascular disease, and congestive heart failure was higher, and patients were older in the hyponatremia group (p < 0.05) than in the normonatremia group. After the adjustment of covariates, hyponatremia was shown to be related to drugs including escitalopram (odds ratio [OR]: 1.82, 95% confidence interval [CI]: 1.20-2.76), trazodone (OR: 2.27, 95% CI: 1.26-4.10), renin angiotensin aldosterone system (RAAS) inhibitors (OR: 1.71, 95% CI: 1.18-2.47), hydrochlorothiazide (OR: 1.83, 95% CI: 1.28-2.62), and opioids (OR: 4.46, 95% CI: 1.24-16.02) (p < 0.05). Polypharmacy, falls, and malnutrition with risk of malnutrition were still significantly associated with increased hyponatremia risk even after adjustment for age, sex, and comorbidity burden (p < 0.05). Conclusions: Hyponatremia seems to be associated with certain geriatric syndromes, as well as the use of some antidepressants and cardiovascular drugs in older adults. Malnourished older adults taking RAAS inhibitors, diuretics, opioids, and antidepressants may be at a higher risk of developing hyponatremia. They should be closely monitored, especially if they are taking multiple medications.

Comment on: Hyponatremia-associated hospital visits are not reduced by early electrolyte testing in older adults starting antidepressants

See the related reply by Lane et al.

The risk of antidepressant-induced hyponatremia: A meta-analysis of antidepressant classes and compounds

BACKGROUND

Hyponatremia (hypoNa) is a potentially serious adverse event of antidepressant treatment. Previous research suggests the risk of drug-induced hyponatremia differs between antidepressants. This meta-analysis sought to determine the risk of antidepressant-induced hypoNa, stratified by different compounds and classes.

METHODS

A PRISMA-compliant systematic search of Web of Science and PubMed databases was performed from inception until Jan 5, 2023, for original studies reporting incidences or risks of hypoNa in adults using antidepressants. We modelled random-effects meta-analyses to compute overall event rates and odds ratios of any and clinically relevant hypoNa for each compound and class, and ran head-to-head comparisons based on hypoNa event rates. We conducted subgroup analyses for geriatric populations and sodium cut-off value. The study is registered with PROSPERO, CRD42021269801.

RESULTS

We included 39 studies (n = 8,175,111). Exposure to antidepressants was associated with significantly increased odds of hypoNa (k = 7 studies, OR = 3.160 (95%CI 1.911-5.225)). The highest event rates were found for SNRIs (7.44%), SSRIs (5.59%), and TCAs (2.66%); the lowest for mirtazapine (1.02%) and trazodone (0.89%). Compared to SSRIs, SNRIs were significantly more likely (k = 10, OR = 1.292 (1.120 - 1.491), p < 0.001) and mirtazapine significantly less likely (k = 9, OR = 0.607 (0.385 - 0.957), p = 0.032) to be associated with hypoNa.

CONCLUSION

Our meta-analysis demonstrated that, while no antidepressant can be considered completely risk-free, for hypoNa-prone patients mirtazapine should be considered the treatment of choice and SNRIs should be prescribed more cautiously than SSRIs and TCAs.

Electrolyte Disturbances Related to Sodium and Potassium and Electroconvulsive Therapy: A Systematic Review

INTRODUCTION

Electrolyte disturbances related to sodium and potassium affect patients with mental disorders undergoing electroconvulsive therapy (ECT). The objective of this study was to systematically summarize the data regarding ECT and electrolyte disturbances related to sodium and potassium.

MATERIALS AND METHODS

A systematic literature review in accordance with PRISMA guidelines was conducted. Clinical studies of patients receiving ECT with electrolyte disturbances reported before or after treatment were included.

RESULTS

We identified nine case reports and two retrospective studies describing electrolyte abnormalities occurring before or after ECT. ECT was effective and safe in patients with hyponatremia and hypernatremia, including the elderly patient population. This treatment was also effective in treating psychiatric symptoms that may persist after ionic equalization. Electrolyte disturbances after ECT were rare. Reports have suggested that succinylcholine used as a muscle relaxant was the main cause of hyperkalemia after ECT.

CONCLUSIONS

Electrolyte control is a crucial aspect of guiding ECT therapy. In the context of sodium-related disorders, it is critical to control patient hydration as part of therapy. In addition, succinylcholine should not be used in patients with immobilization, such as catatonia or neuroleptic malignant syndrome. It is necessary to conduct further studies to clarify whether electrolyte concentration affects ECT parameters and clinical efficacy. In addition, it is necessary to assess the influence of various anesthetics on these conditions during ECT. The result of this review should be interpreted bearing in mind the small number of studies conducted to date and the low quality of the evidence they provide.

[Antidepressant drugs-State of the art]

BACKGROUND

Due to their frequency, complications, and sequelae, depressive disorders are of great significance to patients, their environment, and society. They are considered the most frequent form of mental disturbances in old age. The use of antidepressant drugs (AD) represents a cornerstone of the treatment, which is always multidimensional.

OBJECTIVE

The classification, mechanism of action, efficacy and tolerability of AD are described. Furthermore, the practical treatment procedure as well as special aspects, such as treatment resistance and special features in old age are presented.

MATERIAL AND METHODS

Narrative review incorporating the most recent literature and the new edition of the national healthcare guidelines on unipolar depression.

RESULTS

In the past 20 years, a large number of so-called 2nd generation ADs have been approved worldwide with comparable efficacy but more favorable side effect profiles than conventional (tricyclic) substances. Almost all ADs act by enhancing monoaminergic, mostly serotonergic, neurotransmission. Other common features include a latency in the onset of action, moderate response rates, and potential efficacy on all core symptoms of depression. Side effects can include cardiovascular, metabolic, or sexual dysfunction, but these may significantly differ between drug classes. This enables individualized treatment taking age, individual risk factors, comorbidities and comedications into account.

CONCLUSION

With the correct interpretation of indications, knowledge of the risks, and consideration of the defined precautionary measures outlined here, treatment with AD is a safe and effective tool in the treatment of moderate and severe depression.

Catatonia Due to General Medical Conditions in Psychiatric Patients: Implications for Clinical Practice

Catatonic syndrome is frequently observed over the course of severe mental disorders and general medical conditions, but when catatonia occurs in psychiatric patients with co-morbid medical or neurologic conditions, diagnosis and management may be challenging. Several medical conditions may cause catatonia in psychiatric patients, but some, such as brain injury, infections, hyponatremia and critical illness, may be most relevant in this population. Alongside appropriate etiologic treatment, benzodiazepines and electroconvulsive therapy in refractory cases are effective and safe, and may resolve catatonic syndrome rapidly. When newly-onset psychotic symptoms in catatonic patients with established psychotic disorders occur, delirium should be suspected and appropriately managed. An extensive clinical and laboratory diagnostic workup to determine the underlying etiology of catatonic syndrome should be carried out. In cases of acute multi-morbidity, the exact cause of catatonic syndrome in psychiatric patients may be unclear. It is recommended to avoid antipsychotic drugs in acutely catatonic patients, because they may exacerbate the catatonic symptoms. The akinetic type of catatonia should be differentiated from hypoactive delirium, as treatments for these syndromes differ substantially. When a psychiatric patient presents with symptomatology of both catatonia and delirium, treatment is particularly challenging.

Response to sertraline and antiepileptic drugs in pentylenetetrazole kindling in rats

Anti-epileptic drugs (AEDs) are the mainstay of epilepsy treatment but these may be a potential risk factor for behavioral disturbances particularly depression which requires treatment. In this study, the effect of antidepressant sertraline (SRT) in combination with AEDs sodium valproate (SV) and levetiracetam (LEV) on seizures, cognitive impairment and oxidative stress in rats was evaluated. After administration of 24th injection of pentylenetetrazole (PTZ), 77.8% rats were kindled. Administration of SRT showed no protective effect on kindling development while SV was 100% protective. With LEV 42.9% were kindled. On combining SRT with SV or LEV 25% and 20% rats were kindled. A significant increase in latency to reach platform zone in Morris water maze(MWM), and increased transfer latencies in Elevated plus maze(EPM) was observed in PTZ kindled rats as compared to normal control on day 49 and when LEV was combined with SRT. In EPM test, however none of the drug treatments had any effect on transfer latencies except LEV pretreated kindled group. In Passive avoidance (PA) test, kindling was associated with a significant decrease in retention time(p = 0.018) while LEV and SV had no effect. The PTZ kindled rats showed significantly higher malondialdehyde(MDA) levels in brain hippocampus(p = 0.0286) while both SRT and SV were associated with significantly lower MDA levels as compared to kindled control group. In case of glutathione (GSH), kindling had no significant effect. The use of sertraline for depression in persons with epilepsy on AEDs needs to be carefully evaluated and monitored due to likelihood of individual variation.

Hyponatremia Following Antipsychotic Treatment: In Silico Pharmacodynamics Analysis of Spontaneous Reports From the US Food and Drug Administration Adverse Event Reporting System Database and an Updated Systematic Review

BACKGROUND

Hyponatremia associated with antipsychotic drugs is a rare but potentially life-threatening adverse drug reaction; the underlying pharmacological mechanism has not yet been explained.

METHODS

We investigated the relationship between pharmacological targets of antipsychotic drugs and the occurrence of hyponatremia by conducting a nested case-control study using the Food and Drug Administration Adverse Event Reporting System database. Multiple logistic regression was used to determine the associations between antipsychotics receptor occupancy and hyponatremia. We also performed a systematic review of clinical studies on this association.

RESULTS

Of 139 816 reports involving at least 1 antipsychotic, 1.1% reported hyponatremia. Olanzapine was the most frequently suspected drug (27%). A significant positive association was found between dopamine D3, D4, and hyponatremia, while adrenergic α 1, serotonin 5-HT1A, and 5-HT2A receptor occupancies were negatively associated. A multivariable stepwise regression model showed that dopamine D3 (adj. odds ratio = 1.21; 95% CI = 1.09-1.34; P < .05) predicted the risk for hyponatremia (P < .05), while serotonin 5-HT2A occupancy (Adj. odds ratio = 0.78; 95% CI = 0.68-0.90; P < .01) exhibited a protective effect against hyponatremia. Among the 11 studies included in the systematic review, incidence rates of hyponatremia diverged between 0.003% and 86%, whereas the odds of developing hyponatremia from effect studies ranged between 0.83 and 3.47.

CONCLUSIONS

Antipsychotic drugs having a combined modest occupancy for D3 and 5-HT2A receptors and higher levels of D3 receptor occupancy correspond to different degrees of risk for hyponatremia. Based on the few, relatively large-scale available studies, atypical antipsychotics have a more attenuated risk profile for hyponatremia.

Catatonia Associated with Hyponatremia: Case Report and Brief Review of the Literature

Background:

Catatonia is a syndrome of altered motor behavior that is mostly associated with general medical, neurologic, mood and schizophrenia-spectrum disorders. The association of newly onset catatonic symptoms with hyponatremia has been rarely reported in the literature.

Case Presentation:

We present a rare case of a young female patient with schizophrenia, who presented with catatonic symptoms in the context of hyponatremia due to water intoxication. The symptoms were eliminated with the correction of hyponatremia. There are only a few reports of hyponatremia-associated catatonia in psychiatric and non-psychiatric patients. Sometimes, catatonic symptoms may co-occur with newly onset psychotic symptoms and confusion, suggesting delirium. In several cases, the catatonic symptoms responded to specific treatment with benzodiazepines or electroconvulsive therapy.

Conclusion:

Hyponatremia may induce catatonic symptoms in patients, regardless of underlying mental illness, but this phenomenon is even more relevant in patients with a psychotic or mood disorder, which may itself cause catatonic symptoms. It is important for clinicians not to attribute newly-onset catatonic symptoms to the underlying psychotic or mood disorder without measuring sodium serum levels. The measurement of sodium serum levels may guide treating psychiatrists to refer the patient for further investigation and appropriate treatment.

Prevalence and risk factors for hyponatremia in adult epilepsy patients: Large-scale cross-sectional cohort study

PURPOSE

To evaluate the risk factors and prevalence of hyponatremia among epilepsy patients in relation to use of antiepileptic drugs (AEDs).

METHODS

We retrospectively reviewed 14,620 adult patients (aged 18-103 years) and classified them into the following 3 groups: patients without AED treatment (n = 2165, Group I), patients receiving antiepileptic drugs other than carbamazepine (n = 7442, Group II), and patients treated with carbamazepine (n = 5013, Group III). This study did not include the patients receiving oxcarbazepine or eslicarbazepine acetate because these AEDs are not marketed in Japan. Severe hyponatremia was defined as a serum sodium level < 130 mEq/L.

RESULTS

In Groups I, II, and III, the mean sodium level was 140, 139, and 137 mEq/L, respectively. The highest frequency of severe hyponatremia was observed in Group III (7%), and it was much higher than in Group I (0.8%) or Group II (1.2%). In Groups II and III, old age, low body weight, and concomitant use of phenobarbital, benzodiazepines, or antipsychotics were risk factors for hyponatremia. In Group III, the sodium level decreased as the carbamazepine dose increased. At a carbamazepine dose exceeding 600 mg/day, there was 10.9-fold higher prevalence of hyponatremia, and the risk was potentiated by concomitant use of valproate.

CONCLUSION

The serum sodium level should be monitored carefully when patients are receiving AED polypharmacy combined with antipsychotics. In particular, concomitant administration of valproate enhances the risk of hyperammonemia in patients receiving carbamazepine. These findings may help clinicians to avoid hyponatremia in patients with epilepsy.

The unmasking of hidden severe hyponatremia after long-term combination therapy in exacerbated bipolar patients: a case series

Hyponatremia is occasionally unmasked in psychiatric patients during hospitalization after routine blood and urinary tests, and correlates in most cases with an inappropriate secretion of antidiuretic hormone, mainly due to iatrogenic factors. Only a few studies have regarded the combination of psychotropic drugs as triggers of chronic, asymptomatic hyponatremia in bipolar patients, who require to be hospitalized because of the exacerbation of their mental illness. We presented three clinical cases of patients affected by a long-term psychiatric disorder and under polypharmacotherapy for several months. After excluding other potential factors, we hypothesized that pharmacological treatment with a mood stabilizer (oxcarbazepine) associated with a benzodiazepine (delorazepam), a second-generation antipsychotic (olanzapine) or an antidepressant (fluvoxamine), triggered severe hyponatremia ([Na+] ≤125 mEq/L), serum hypo-osmolarity, and elevated inappropriate urine osmolarity added to more diluted sodium concentration. When we discontinued the treatment, clinical conditions of our patients improved, despite the previous administration of hypertonic saline jointly with water restriction. Psychiatrists should consider that bipolar patients on long-term polypharmacotherapy may present a higher risk of severe hyponatremia not clinically detectable. Consequently, routine laboratory tests should be periodically repeated as they represent the only available tool to unmask such electrolyte imbalances.

Duloxetine-Induced Hyponatremia in an Elderly Male Patient with Treatment-Refractory Major Depressive Disorder

Several classes of antidepressants can induce syndrome of inappropriate antidiuretic hormone hypersecretion (SIADH), thereby causing hyponatremia. Initial symptoms of hyponatremia include neuropsychiatric and gastrointestinal manifestations can mimic depression, especially in elderly people with multiple somatic complaints. Here we present a case of a 68-year-old man with treatment-refractory depression and general anxiety disorder who developed duloxetine-induced hyponatremia. His symptoms of hyponatremia including unsteady gait, dizziness, nausea, general malaise, and poor appetite subsided after discontinuing the offending medication. Our case illustrates that drug-induced SIADH and potential drug-drug interactions should be considered in elderly patients who develop hyponatremia following the initiation of antidepressants.

[Psychiatric pharmacotherapy of older individuals with severe mental illness]

BACKGROUND

Chronic schizophrenia, depression, and bipolar disorders, among other chronic psychiatric disorders with onset at youth or early adulthood are often referred to as severe mental illness (SMI). Aging with SMI is associated with various psychosocial, physiological, and medical problems with potential impact on psychiatric pharmacotherapy.

OBJECTIVES

Determination and discussion of problems and special features of the psychopharmacological treatment of older persons with SMI and presentation of treatment recommendations for the distinct diagnoses.

MATERIALS AND METHODS

International literature and guidelines were searched. In addition, the basic literature and expert opinions are discussed.

RESULTS

General problems that influence the psychiatric pharmacotherapy of older persons with SMI include nonadherence, nonresponse, polypharmacy, and distinct pharmacokinetic changes with aging and somatic comorbidity. Psychotropic drugs may exhibit cardiovascular, metabolic, and neuropsychiatric risks, among others. The literature regarding effectiveness of psychotropic drugs, drug groups, or combination of drugs in older patients with SMI is scarce to nonexistent.

CONCLUSIONS

Drug treatment of older persons with SMI should be part of an overall treatment plan that also has to include social and psychotherapeutic components that address the specific problems of this population. Most importantly, psychiatric pharmacotherapy should consider these risks and the treatment should be tailored to a patient's individual risk profile. Due to a general lack of evidence in this special population, treatment strategies of standard guidelines should be adjusted with special consideration to physiological changes of age.

Hyponatremia, falls and bone fractures: A systematic review and meta-analysis

OBJECTIVE

To perform a meta-analysis based on published studies that compared falls and bone fractures between patients with and without hyponatremia.

CONTEXT

There is evidence suggesting that hyponatremia is associated with an increased risk of falls and bone fractures.

DESIGN

An extensive Medline, Embase and Cochrane search was performed to retrieve all studies published up to, 30 April 2017, using the following words: "hyponatremia" or "hyponatraemia" AND "falls" and "bone fractures." A meta-analysis was performed including all studies comparing falls and bone fractures in subjects with or without hyponatremia.

PATIENTS AND RESULTS

Of 216 retrieved articles, 15 studies satisfied inclusion criteria encompassing a total of 51 879 patients, of whom 2329 were hyponatremic. Across all studies, hyponatremia was associated with a significantly increased risk of falls (MH-OR = 2.14[1.71; 2.67]. This result was confirmed when only hospitalized patients were considered (MH-OR = 2.44 [1.97; 3.02]). A meta-regression analysis showed that the hyponatremia-related risk of falls was higher in those studies considering a lower serum [Na+ ] cut-off to define hyponatremia. Interestingly, the estimated risk of falls related to hyponatremia was already significantly higher when a serum [Na+ ] cut-off of 135 mmol/L was considered (MH-OR = 1.26[1.23;1.29]). The presence of hyponatremia was also associated with a higher risk of fractures, particularly hip fractures (MH-OR = 2.00[1.43;2.81]).

CONCLUSIONS

This study confirms that hyponatremia is associated with an increased risk of falls and bone fractures. The clinical, social and economic relevance of such association is strengthened by the increased incidence of hyponatremia in older people.

Hyponatremia in Association With Second-Generation Antipsychotics: A Systematic Review of Case Reports

BACKGROUND

Hyponatremia is generally defined as a serum sodium level <135 mmol/L and is considered severe if serum sodium is <125 mmol/L. Hyponatremia is a potentially life-threatening medical comorbidity for patients with schizophrenia. The incidence of hyponatremia in patients with schizophrenia who are taking second-generation antipsychotics (SGAs) has not been well established.

METHODS

We conducted a systematic review of case reports of hyponatremia associated with the use of SGAs in patients with schizophrenia. We searched MEDLINE (from 1946 through September 2016) using the medical subject headings antipsychotic agents, hyponatremia, and water intoxication to identify reported diagnoses of hyponatremia following treatment with SGAs in patients with schizophrenia.

RESULTS

We abstracted 12 potentially relevant case reports from 157 records. Nine case reports met the selection criteria. Three cases involved the use of aripiprazole (Abilify), 3 involved the use of risperidone (Risperdal), and the other 3 cases involved ziprasidone, olanzapine, and clozapine. Approximately equal numbers of males and females were represented, and 2 of the 9 patients were aged ≥60 years. The average patient age was 47 years, and the average time to the hyponatremia event was 17 days. The average serum sodium was 138 mmol/L at baseline, 112 mmol/L at treatment nadir, and 138 mmol/L after treatment discontinuation.

CONCLUSION

Hyponatremia can result from the use of SGAs in patients with schizophrenia and can be avoided with proper management of treatment. Physicians, psychiatrists, and other healthcare workers should be aware of the potential for severe hyponatremia with the use of commonly prescribed SGAs. SGA-induced hyponatremia is generally reversible after discontinuing treatment.

Concurrence of Inappropriate Antidiuretic Hormone Secretion and Cerebral Salt Wasting Syndromes after Traumatic Brain Injury

Syndrome of inappropriate antidiuretic hormone (SIADH) and cerebral salt wasting syndrome (CSWS) as the two most common neuroendocrine diseases, have been recognized and understood by many neurologists. Although SIADH and CSWS are the common causes of central hyponatremia after traumatic brain injury (TBI), a few cases are mixed, with the coexistence of the two pathological pathomechanism. However, the mixed type of both SIADH and CSWS has not been clearly reported in any literature. Here, we present the first description of the concurrent syndrome of SIADH and CSWS after TBI in four patients who underwent standard diagnostic procedures, treatment and follow up. Our findings further support that this rare neuroendocrine disease may exist in clinical practice, in which the traditional-conventional treatment shows poor efficacy.

Fatal Cerebral Edema, Seizures, and Hyponatremia After Trazodone Overdose

Trazodone is a serotonin antagonist and reuptake inhibitor that is widely used for the treatment of depression and insomnia. Fatal overdose is rare and usually occurs when combined with other drugs or alcohol. Only a few lethal cases of pure trazodone overdose have been reported, all attributed to cardiotoxicity. We reported a 37-year-old woman who presented after ingesting 6.45 g of trazodone in a suicidal attempt. She was hyponatremic because of the syndrome of inappropriate antidiuretic hormone secretion and, shortly after, had a seizure and developed fatal cerebral edema. Others have described seizures and hyponatremia after pure trazodone overdose, but this is the first report of cerebral edema and death from a neurological complication. Careful monitoring and correction of sodium levels may be necessary in these patients.

Hyponatraemia - presentations and management

Hyponatraemia is the most common electrolyte disturbance encountered in clinical practice. It is associated with -significant morbidity and mortality, thus appropriate investigation and treatment is essential. Hyponatraemia presents with a spectrum of clinical presentations ranging from no symptoms to life-threatening neurological sequelae. Hyponatraemia has multiple aetiologies and distinguishing the underlying aetiology facilitates appropriate treatment. This review provides an overview of the presentations and approaches to management of this common clinical condition.

Antipsychotic use is a risk factor for hyponatremia in patients with schizophrenia: a 15-year follow-up study

RATIONALE

Hyponatremia affects 10% of patients with chronic schizophrenia and can lead to severe consequences. However, the role of antipsychotics and other risk factors in hyponatremia occurrence has remained inconsistent.

OBJECTIVE

This study examined the association between antipsychotic use and hyponatremia occurrence in patients with schizophrenia.

METHODS

We utilized the National Health Insurance Research Database to follow 2051 patients with schizophrenia from 1998 to 2013. Among them, 137 (6.7%) developed hyponatremia. Sociodemographic characteristics, physical comorbidities, and psychiatric treatment experiences were compared between those who had hyponatremia and those who did not. A Cox proportional hazards model was used to examine the hazard ratios (HRs) of these characteristics.

RESULTS

In patients with hyponatremia, the mean age at first hyponatremia occurrence was 54.7 ± 13.9 years, an average of 9.5 ± 4.0 years after schizophrenia diagnosis, and 32.9% of them were off antipsychotics before hyponatremia occurrences. Age at schizophrenia diagnosis (HR = 1.1), low-income household (HR = 2.4), comorbidities (HR = 1.2), and psychiatric admissions (HR = 1.04) were associated with the risks of hyponatremia. Compared with no antipsychotic use, atypical (HR = 2.1) and typical antipsychotics (HR = 3.1) were associated with an elevated risk of hyponatremia, after adjustment for age, sex, and physical comorbidities. Carbamazepine use (HR = 2.9) was also a significant risk factor for hyponatremia (p < 0.05).

CONCLUSIONS

Antipsychotic use in patients with schizophrenia with polypharmacy should be monitored for hyponatremia occurrences. Clinicians should pay attention to the impact of poor living conditions on hyponatremia occurrence.

Antidepressants and the risk of hyponatremia: a Danish register-based population study

OBJECTIVE

To examine the association between classes of antidepressants and hyponatremia, and between specific antidepressants and hyponatremia.

DESIGN

Retrospective register-based cohort study using nationwide registers from 1998 to 2012.

SETTING

The North Denmark Region.

PARTICIPANTS

In total, 638 352 individuals were included.

PRIMARY AND SECONDARY OUTCOME MEASURES

Plasma sodium was obtained from the LABKA database. The primary outcome was hyponatremia defined as plasma sodium (p-sodium) below 135 mmol/L and secondary outcome was severe hyponatremia defined as p-sodium below 130 mmol/L. The association between use of specific antidepressants and hyponatremia was analysed using multivariable Poisson regression models.

RESULTS

An event of hyponatremia occurred in 72 509 individuals and 11.36% (n=6476) of these events happened during treatment with antidepressants. Incidence rate ratios and CIs for the association with hyponatremia in the first p-sodium measured after initiation of treatment were for citalopram 7.8 (CI 7.42 to 8.20); clomipramine 4.93 (CI 2.72 to 8.94); duloxetine 2.05 (CI 1.44 to 292); venlafaxine 2.90 (CI 2.43 to 3.46); mirtazapine 2.95 (CI 2.71 to 3.21); and mianserin 0.90 (CI 0.71 to 1.14).

CONCLUSIONS

All antidepressants except mianserin are associated with hyponatremia. The association is strongest with citalopram and lowest with duloxetine, venlafaxine and mirtazapine.

Drug-Related Hyponatremic Encephalopathy: Rapid Clinical Response Averts Life-Threatening Acute Cerebral Edema

Patient: Female, 63

Final Diagnosis: Drug-induced hyponatremic encephalopathy

Symptoms: Seizures • coma

Medication: Hypertonic 3% saline infusion

Clinical Procedure: —

Specialty: Internal Medicine

Hyponatraemia and confusion in a 70-year-old female when bupropion was added to dothiepin and escitalopram

OBJECTIVE

Hyponatraemia secondary to syndrome of inappropriate antidiuretic hormone secretion (SIADH) is a well-recorded adverse event observed in elderly patients on antidepressant treatment. Bupropion is an antidepressant agent usually reserved as an augmentation strategy for treatment-resistant depression. While hyponatraemia is not a documented side effect of bupropion, there are a few cases outside of Australia reported in the literature. We report on a case of hyponatraemia observed on bupropion initiation in a 70-year-old female patient with treatment-resistant depression. We present a discussion of the possible mechanism of action for the hyponatraemia observed in our case and prior reported cases.

CONCLUSIONS

Our case and review of the available literature highlights the dangers of polypharmacy in the management of treatment-resistant depression. Our findings suggest that the association of hyponatraemia with bupropion in our and subsequent cases was likely the result of medication interaction and not a direct side effect of bupropion. Where bupropion is being used as an augmenting agent in the treatment of depression we would suggest checking of serum sodium prior to commencement of bupropion, and monitoring thereafter. This is especially important in elderly patients where other risk factors for hyponatraemia are likely to be present.

Dehydration, Hypernatremia, and Hyponatremia

Disturbances of serum sodium are one of the most common findings in older persons. They are also a major cause of hospital admissions and delirium and are associated with frailty, falls, and hip fractures. Both hypernatremia and hyponatremia are potentially preventable. Treatment involves treating the underlying cause and restoring sodium and volume status to normal. The arginine vasopressin antagonists, vaptans, have increased the therapeutic armamentarium available to physicians.

Pharmacokinetic and pharmacodynamic interactions between antiepileptics and antidepressants

INTRODUCTION

Antiepileptic-antidepressant combinations are frequently used by clinicians; their pharmacokinetic (PK) and pharmacodynamic (PD) drug interactions (DIs) have not been well studied but are frequently likely to be clinically relevant.

AREAS COVERED

This article provides a comprehensive review of PK DIs between antiepileptics and antidepressants. In the absence of PD DI studies, PD information on pharmacological mechanisms and studies on efficacy and safety of individual drugs are reviewed.

EXPERT OPINION

The clinical relevance of the inductive properties of carbamazepine, phenytoin, phenobarbital and primidone and the inhibitory properties of valproic acid and some antidepressants are well understood; correction factors are provided if appropriate DI studies have been completed. More PK studies are needed for: i) antiepileptics with potent inductive effects for all recently approved antidepressants; ii) high doses of mild CYP3A4 inducers, such as clobazam, eslicarbazepine, oxcarbazepine, rufinamide and topiramate for reboxetine and vilazodone; iii) valproate as a possible inhibitor, mild inducer or both a mild inducer and competitive inhibitor of some antidepressants; and iv) inhibitory effects of long-term fluoxetine use on clobazam, lacosamide, phenobarbital, primidone, carbamazepine, felbamate, tiagabine and zonisamide. Possible synergistic or additive beneficial PD DIs in generalized anxiety disorder, chronic pain, migraine prophylaxis, weight control and menopausal symptoms need study.