Review of carbamazepine-induced hyponatremia

Antiseizure Medications for the Prophylaxis of Migraine during the Anti- CGRP Drugs Era

Migraine and epilepsy are fundamentally distinct disorders that can frequently coexist in the same patient. These two conditions significantly differ in diagnosis and therapy but share some widely- used preventive treatments. Antiseizure medications (ASMs) are the mainstay of therapy for epilepsy, and about thirty different ASMs are available to date. ASMs are widely prescribed for other neurological and non-neurological conditions, including migraine. However, only topiramate and valproic acid/valproate currently have an indication for migraine prophylaxis supported by high-quality evidence. Although without specifically approved indications and with a low level of evidence or recommendation, several other ASMs are used for migraine prophylaxis. Understanding ASM antimigraine mechanisms, including their ability to affect the pro-migraine calcitonin gene-related peptide (CGRP) signaling pathway and other pathways, may be instrumental in identifying the specific targets of their antimigraine efficacy and may increase awareness of the neurobiological differences between epilepsy and migraine. Several new ASMs are under clinical testing or have been approved for epilepsy in recent years, providing novel potential drugs for migraine prevention to enrich the treatment armamentarium and drugs that inhibit the CGRP pathway.

Characterization in Inhibitory Effectiveness of Carbamazepine in Voltage-Gated Na+ and Erg-Mediated K+ Currents in a Mouse Neural Crest-Derived (Neuro-2a) Cell Line

Carbamazepine (CBZ, Tegretol^®) is an anticonvulsant used in the treatment of epilepsy and neuropathic pain; however, several unwanted effects of this drug have been noticed. Therefore, the regulatory actions of CBZ on ionic currents in electrically excitable cells need to be reappraised, although its efficacy in suppressing voltage-gated Na⁺ current (I_Na) has been disclosed. This study was undertaken to explore the modifications produced by CBZ on ionic currents (e.g., I_Na and erg-mediated K⁺ current [I_K(erg)]) measured from Neuro-2a (N2a) cells. In these cells, we found that this drug differentially suppressed the peak (transient, I_Na(T)) and sustained (late, I_Na(L)) components of I_Na in a concentration-dependent manner with effective IC₅₀ of 56 and 18 μM, respectively. The overall current–voltage relationship of I_Na(T) with or without the addition of CBZ remained unchanged; however, the strength (i.e., ∆area) in the window component of I_Na (I_Na(W)) evoked by the short ascending ramp pulse (V_ramp) was overly lessened in the CBZ presence. Tefluthrin (Tef), a synthetic pyrethroid, known to stimulate I_Na, augmented the strength of the voltage-dependent hysteresis (Hys_(V)) of persistent I_Na (I_Na(P)) in response to the isosceles-triangular V_ramp; moreover, further application of CBZ attenuated Tef-mediated accentuation of I_Na(P)’s Hys_(V). With a two-step voltage protocol, the recovery of I_Na(T) inactivation seen in Neuro-2a cells became progressively slowed by adding CBZ; however, the cumulative inhibition of I_Na(T) evoked by pulse train stimulation was enhanced during exposure to this drug. Neuro-2a-cell exposure to CBZ (100 μM), the magnitude of erg-mediated K⁺ current measured throughout the entire voltage-clamp steps applied was mildly inhibited. The docking results regarding the interaction of CBZ and voltage-gate Na⁺ (Na_V) channel predicted the ability of CBZ to bind to some amino-acid residues in Na_V due to the existence of a hydrogen bond or hydrophobic contact. It is conceivable from the current investigations that the I_Na (I_Na(T), I_Na(L), I_Na(W), and I_Na(P)) residing in Neuro-2a cells are susceptible to being suppressed by CBZ, and that its block on I_Na(L) is larger than that on I_Na(T). Collectively, the magnitude and gating of Na_V channels produced by the CBZ presence might have an impact on its anticonvulsant and analgesic effects occurring in vivo.

Carbamazepine-induced hyponatremia - A wakeup call

Carbamazepine-induced hyponatremia is a rare condition. The patients may or may not be symptomatic. Epilepsy is considered a social taboo. Hence, patients do not reveal history of being on antiepileptic agents. Carbamazepine is a known antiepileptic and psychotropic agent. It is commonly used for the treatment of seizures and psychiatric disorders. We present a case of a 60-year-old female patient presenting in emergency department with history of carbamazepine-induced hyponatremia. It raises antidiuretic hormone (ADH) levels. This leads to increased sensitivity of renal tubules to ADH levels. She was diagnosed as a case of syndrome of inappropriate ADH and was treated accordingly. She was asymptomatic and was ambulatory. She recovered significantly. Hence, it is essential to monitor sodium levels in patients on carbamazepine therapy and also on drugs with similar mechanism of action.

Carbamazepine adverse drug reactions

INTRODUCTION

Carbamazepine (CBZ) is used for the treatment of epilepsy and other neurological and psychiatric disorders. The occurrence of adverse reactions (ADRs) to CBZ can negatively impact the quality of life of patients, as well as increase health-care costs. Thus, knowledge of CBZ-induced ADRs is important to achieve safer treatment outcomes. Areas covered: This review describes the clinical features, known mechanisms, and clinical management of the main CBZ-induced ADRs. In addition, pharmacogenetic studies focused on ADRs induced by CBZ are cited. Expert commentary: CBZ-induced ADRs are well known in the literature. The metabolite CBZ-10,11-epoxide plays an important role in the mechanism that underlies the ADRs induced by CBZ. Several factors should be considered for a safer use of CBZ, such as monotherapy prescription when possible, an adequate dose titration, knowledge of previous ADRs in the patient, and routine monitoring of CBZ plasma concentrations in symptomatic patients. Pharmacogenetics is a potential tool for CBZ therapy improvement, and the design of multicenter studies focused on the identification of biomarkers for CBZ-induced ADRs could provide useful information for a safer CBZ therapy.

Epidemiology, pathophysiology and putative genetic basis of carbamazepine- and oxcarbazepine-induced hyponatremia

The use of carbamazepine (CBZ) and oxcarbazepine (OXC) as first-line antiepileptic drugs in the treatment of focal epilepsy is limited by hyponatremia, a known adverse effect. Hyponatremia occurs in up to half of people taking CBZ or OXC and, although often assumed to be asymptomatic, it can lead to symptoms ranging from unsteadiness and mild confusion to seizures and coma. Hyponatremia is probably due to the antidiuretic properties of CBZ and OXC that are, at least partly, explained by stimulation of the vasopressin 2 receptor/aquaporin 2 pathway. No known genetic risk variants for CBZ- and OXC-induced hyponatremia exist, but likely candidate genes are part of the vasopressin water reabsorption pathway.

Use of Antiepileptic Drugs in Patients with Chronic Kidney Disease and End Stage Renal Disease

Epilepsy is a disorder with an approximate worldwide prevalence of 1%. Due to complexities of metabolism, protein-binding, renal elimination, and other pharmacokinetic parameters, the dosing of antiepileptic drugs (AEDs) in patients with chronic kidney disease (CKD) or end stage renal disease (ESRD) deserves special attention. This is a review of the most commonly prescribed AEDs with special focus on their indication, pharmacokinetics, and unique considerations for use in patients with CKD and ESRD. A review of their renal toxicities is also included.

Psychogenic polydipsia in bipolar affective disorder--a case report

Polydipsia is a less examined but prevalent condition in patients with psychiatric disorders. It is usually described in schizophrenia but is rarely reported in bipolar affective disorder (BPAD). It is important to recognize and treat this entity as it can lead to serious complications. One needs to be cautious in choosing the mood stabilizer while treating this condition. We report the successful treatment of a patient with BPAD and polydipsia on a combination of valproate and risperidone.

Adverse endocrine and metabolic effects of psychotropic drugs: selective clinical review

The article critically reviews selected, clinically significant, adverse endocrine and metabolic effects associated with psychotropic drug treatments, including hyperprolactinaemia, hyponatraemia, diabetes insipidus, hypothyroidism, hyperparathyroidism, sexual dysfunction and virilization, weight loss, weight gain and metabolic syndrome (type 2 diabetes mellitus, dyslipidaemia and hypertension). Such effects are prevalent and complex, but can be managed clinically when recognized. They encourage continued critical assessment of benefits versus risks of psychotropic drugs and underscore the importance of close coordination of psychiatric and general medical care to improve long-term health of psychiatric patients. Options for management of hyperprolactinaemia include lowering doses, switching to agents such as aripiprazole, clozapine or quetiapine, managing associated osteoporosis, carefully considering the use of dopamine receptor agonists and ruling out stress, oral contraceptive use and hypothyroidism as contributing factors. Disorders of water homeostasis may include syndrome of inappropriate antidiuretic hormone (SIADH), managed by water restriction or slow replacement by hypertonic saline along with drug discontinuation. Safe management of diabetes insipidus, commonly associated with lithium, involves switching mood stabilizer and consideration of potassium-sparing diuretics. Clinical hypothyroidism may be a more useful marker than absolute cut-offs of hormone values, and may be associated with quetiapine, antidepressant and lithium use, and managed by thyroxine replacement. Hyper-parathyroidism requires comprehensive medical evaluation for occult tumours. Hypocalcaemia, along with multiple other psychiatric and medical causes, may result in decreased bone density and require evaluation and management. Strategies for reducing sexual dysfunction with psychotropics remain largely unsatisfactory. Finally, management strategies for obesity and metabolic syndrome are reviewed in light of the recent expert guidelines, including risk assessment and treatments, such as monoamine transport inhibitors, anticonvulsants and cannabinoid receptor antagonists, as well as lifestyle changes.

The International Society for Bipolar Disorders (ISBD) consensus guidelines for the safety monitoring of bipolar disorder treatments

OBJECTIVES

Safety monitoring is an important aspect of bipolar disorder treatment, as mood-stabilising medications have potentially serious side effects, some of which may also aggravate existing medical comorbidities. This paper sets out the International Society for Bipolar Disorders (ISBD) guidelines for the safety monitoring of widely used agents in the treatment of bipolar disorder. These guidelines aim to provide recommendations that take into consideration the balance between safety and cost-effectiveness, to highlight iatrogenic and preventive clinical issues, and to facilitate the broad implementation of therapeutic safety monitoring as a standard component of treatment for bipolar disorder.

METHODS

These guidelines were developed by an ISBD workgroup, headed by the senior author (MB), through an iterative process of serial consensus-based revisions. After this, feedback from a multidisciplinary group of health professionals on the applicability of these guidelines was sought to develop the final recommendations.

RESULTS

General safety monitoring recommendations for all bipolar disorder patients receiving treatment and specific monitoring recommendations for individual agents are outlined.

CONCLUSIONS

These guidelines are derived from evolving and often indirect data, with minimal empirical cost-effectiveness data available to provide guidance. These guidelines will therefore need to be modified to adapt to different clinical settings and health resources. Clinical acumen and vigilance remain critical ingredients for safe treatment practice.

Interferon-alpha is a predisposing risk factor for carbamazepine-induced hyponatremia: A case of syndrome of inappropriate antidiuresis caused by interferon-alpha therapy

A 31-year-old man had been treated with carbamazepine (CBZ) for 6 years and warfarin with bucolome for 2 years before developing hyponatremia 7 days after an injection of interferon-alpha 2b and starting oral ribavirin for chronic hepatitis C virus infection. Despite the hyponatremia, urinary osmolality exceeded plasma osmolality, and urinary excretion volume decreased markedly after water loading. Restriction of water intake and administration of dimethylchlortetracycline improved the hyponatremia, and lithium therapy maintained the normonatremia for one year. The hyponatremia recovered 6 months after the interferon-alpha 2b therapy was completely stopped. In the present case, the syndrome of inappropriate antidiuresis may have been caused by the effect of interferon-alpha 2b on the renal distal tubules that had been sensitized by CBZ. Patients on CBZ therapy should be carefully observed for the development of hyponatremia when they are started on interferon-alpha 2b injections.

Hyponatremia-induced seizure during carbamazepine treatment

We report the case of a 54-year-old woman who was admitted for benzodiazepine withdrawal. After 6 weeks of carbamazepine treatment (600, then 200 mg) the patient suddenly suffered from a grand mal seizure. Laboratory findings revealed a clinical significant hyponatremia of Na 125 mmol/l (baseline: 143 mmol/l). CCT and ECG were normal. To our knowledge, this is the first description of a seizure related to hyponatremia in an adult carbamazepine-treated patient.

Long-term Use of Atypical Antipsychotics in Bipolar Disorder

Bipolar disorder is a chronic disease that may require lifetime treatment. The maintenance therapy of bipolar disorder can be challenging for the treating clinician. Currently, according to the American Psychiatric Association (APA) guidelines, lithium, valproic acid, lamotrigine, carbamazepine, oxcarbazepine, and the antipsychotics are recommended for the maintenance treatment of bipolar disorder. The antipsychotics are recommended to be continued only if the clinician decides that they are necessary for the control of persistent psychosis or for prophylaxis against recurrence. Although the APA guidelines provide sufficient evidence for the use of these mood stabilizers, newer drugs such as the atypical antipsychotics are being investigated for use in the maintenance phase of treatment of bipolar disorder.

Endocrine and metabolic adverse effects of psychotropic medications in children and adolescents

OBJECTIVE

Despite increasing use of psychotropic medications in children and adolescents, data regarding their efficacy and safety are limited. Endocrine and metabolic adverse effects are among the most concerning adverse effects of commonly used psychotropic medications.

METHOD

Selective review of endocrine and metabolic effects of psychotropic medications in pediatric populations, with a focus on monitoring and management strategies.

RESULTS

Because youth are still developing at the time of psychotropic drug exposure, most reference values need to be adjusted for gender and age. As in adults, youngsters receiving lithium require monitoring for thyroid dysfunction. Psychostimulants appear to cause mild reversible growth retardation in some patients, most likely because of decreased weight or slowing of expected weight gain; some patients may experience clinically significant reductions in adult height. Although still controversial, valproate use has been associated with an increased risk for polycystic ovary syndrome, in addition to causing weight gain. Although more data are required, children and adolescents appear to be at higher risk than adults for antipsychotic-induced hyperprolactinemia, weight gain, and possibly, associated metabolic abnormalities, which is of particular concern.

CONCLUSIONS

Clinicians and caregivers need to be aware of potential endocrine and metabolic adverse effects of psychiatric medications. A careful selection of patients, choice of agents with potentially lesser risk for these adverse events, healthy lifestyle counseling, as well as close health monitoring are warranted to maximize effectiveness and safety.

Safety and tolerability of mood-stabilising anticonvulsants in the elderly

The authors review current research on the safety and tolerability of anticonvulsant medications used for individuals over the age of 60 years with affective disorders, agitation and other psychiatric disorders. Three anticonvulsants currently approved in the US for treatment of bipolar affective disorder are reviewed: valproate, lamotrigine and extended-release carbamazepine. The authors discuss the pharmacokinetics, pharmacodynamics, drug-drug interactions and the impact of ageing for each drug. There are few studies of anticonvulsant medications in elderly patients with bipolar disorder or other psychiatric conditions. Therefore, the authors summarise adverse events of greatest prevalence and/or greatest severity based on data derived predominately from studies of geriatric patients with epilepsy and/or other non-psychiatric indications. Guidelines are offered for the safe use of these medications in the elderly, based on research literature.

Carbamazepine-Induced Hyponatremia: Assessment of Risk Factors

OBJECTIVE

To report a case of carbamazepine-induced acute hyponatremia resulting in seizures.

CASE SUMMARY

A 44-year-old white woman developed acute hyponatremia and 2 subsequent tonic–clonic seizures after ingesting twice her evening dose of carbamazepine (usual evening dose 600 mg). On admission, her serum sodium level was 122 mEq/L. An infusion of NaCl 0.9% was begun and, within 24 hours, the serum sodium level had returned to her previous level of 136 mEq/L. The woman's preadmission carbamazepine concentration was 8.6 μg/mL, and it was 11.3 μg/mL on admission. Carbamazepine was withheld and, the following day, the concentration was 5.6 μg/mL. The woman had experienced a similar event 6 months earlier when she also took a large dose of carbamazepine.

DISCUSSION

We attributed the acute hyponatremia and seizures to the large increase in dose of carbamazepine in the presence of other risk factors for hyponatremia. Hyponatremia associated with carbamazepine has been well described. The incidence ranges from 1.8% to 40% depending on the patient population studied. Severe hyponatremia in patients treated with monotherapy is uncommon. Several risk factors have been reported to increase the risk of hyponatremia including age >40 years, concomitant use of medications associated with hyponatremia, menstruation, psychiatric condition, surgery, psychogenic polydipsia, and female gender. Treatment is focused on removal of the precipitating factors or discontinuation of carbamazepine therapy. Use of the Naranjo probability scale indicated a highly probable relationship between acute hyponatremia and carbamazepine in our patient.

CONCLUSIONS

Hyponatremia with carbamazepine is well known. The factors associated with increased risk are less understood. An increased awareness of these risks, careful monitoring, and patient education are important in the prevention of neurologic complications.

Psychopharmacological treatment with lithium and antiepileptic drugs: suggested guidelines from the Danish Psychiatric Association and the Child and Adolescent Psychiatric Association in Denmark

A subcommittee under the Danish Psychiatric Association and the Child and Adolescent Psychiatric Association in Denmark have recently developed national guidelines for the psychopharmacological treatment with lithium and antiepileptic drugs, and the present translation aims at contributing to the international discussion on the development of proper guidelines for the treatment of bipolar disorder. Among the antiepileptic drugs, the report deals with valproate, carbamazepine and lamotrigine and to a lesser extent with oxcarbazepine, gabapentin and topiramate. The various drugs will be reviewed, outlining the scientific evidence for mood-stabilizing properties and discussing major side effects, the most important interactions with other drugs and practical use. Special considerations during pregnancy and lactation, during treatment of children and adolescents and during treatment of the elderly will also be presented. Antidepressants and antipsychotics are beyond the scope of the report, but due to the mood-stabilizing properties of at least some of the atypical antipsychotics, these agents will be brought into some focus in connection with the overall treatment guidelines for the different phases of bipolar disorder given at the end of this report.

Sodium and Potassium Disturbances in the Elderly

OBJECTIVE

To study the incidence of sodium and potassium disturbances in a population of the very old elderly, with respect to medication with potential effects on electrolyte levels.

DESIGN AND SETTING

Cross-sectional study of subjects aged >/=75 years, based on data from the Kungsholmen project, a population-based study of elderly in an urban area of Stockholm, Sweden.

STUDY PARTICIPANTS

1558 elderly individuals (1178 women and 380 men), mean age 81.4 years, providing information about drug use and serum electrolyte data.

MAIN OUTCOME MEASURES

Data on drug use was based on personal interviews. Hyponatraemia was defined as a serum sodium concentration <136 mmol/L, hypernatraemia as a serum sodium concentration >146 mmol/L, hypokalaemia as a serum potassium concentration <3.5 mmol/L and hyperkalaemia as a serum potassium concentration >5.0 mmol/L.

RESULTS

Hyponatraemia was found in 147 subjects (9.4% of the study population) and hypernatraemia in five individuals (0.3%). Hypokalaemia was found in 39 (2.5%) and hyperkalaemia in 43 (2.8%) of the subjects. The prevalence of hyponatraemia (p < 0.001), hypokalaemia (p < 0.05) and hyperkalaemia (p < 0.05) increased with age. Hyponatraemia was found more often in women than in men (p < 0.05). Hypernatraemia was more frequent in subjects who lived in institutions (p < 0.001). The occurrence of hyponatraemia was associated with the use of carbamazepine, laxatives (enema), diuretics and ACE-inhibitors; hypernatraemia was associated with osmotically active laxatives. Hypokalaemia was associated with thiazide-related and combination diuretics; and hyperkalaemia was associated with potassium-sparing diuretics, beta-blockers, cytostatic drugs and tricyclic antidepressants.

CONCLUSIONS

The present study demonstrated the association between electrolyte level disturbances and several types of drugs in a population of the very old elderly. Our results underline the importance of monitoring serum electrolyte levels in the elderly, not only in relation to the use of diuretics, but also several other drugs.

Carbamazepine-related hyponatremia following cardiopulmonary bypass

A 67-year-old man on long-term carbamazepine therapy underwent elective coronary artery bypass grafting. Following an initially uncomplicated recovery, he developed symptomatic hyponatremia. The symptoms and biochemical abnormality improved after gradual discontinuation of carbamazepine. We discuss the association between carbamazepine and hyponatremia and the causes of hyponatremia after cardiopulmonary bypass. Surgeons should consider stopping carbamazepine before operations with cardiopulmonary bypass.

Hyponatraemia associated with psychotropic medications. A review of the literature and spontaneous reports

Psychotropic medication-induced hyponatraemia is an uncommon but important clinical problem with potential serious consequences if not recognised and treated early. Several risk factors have been associated with the development of hyponatraemia. This article reviews reported cases of hyponatraemia associated with the use of psychotropic medications and evaluates possible risk factors and causes. The data were sourced by a search of Medline for reports of hyponatraemia associated with the use of psychotropic medication between January 1966 and December 2000 and a search of US Food and Drug Administration (FDA) spontaneous reporting system database between January 1966 and December 1999. All the reports were included in this review. In the case reports the following data were assessed: age, gender, daily dosage, days to onset, days to recovery, medical condition, concurrent medications. Several risk factors were identified: advanced age, female gender, use of other medications, medical comorbidity. The risk of hyponatraemia was found to be higher during the first 2 weeks of treatment. Administration of the dosage of the drug was not found to be related to the development of hyponatraemia. Hyponatraemia can cause confusion, agitation and lethargy. Any change in the course of illness should alert the physician to the possibility of hyponatraemia.

Effects of oxcarbazepine on sodium concentration and water handling

Oxcarbazepine, a keto-analogue of carbamazepine, was recently approved in the United States for the treatment of seizures of partial onset. Some patients treated with oxcarbazepine showed the development of hyponatremia, which in most instances was asymptomatic. Understanding the mechanisms by which oxcarbazepine can lead to a reduction of serum sodium levels could have therapeutic implications for the few patients in whom symptomatic hyponatremia develops. In this study, we evaluated sodium and water handling in patients with epilepsy and in healthy subjects titrated over 3 weeks to a maximum daily oxcarbazepine dose of 2,400mg. All subjects were evaluated in a hospital setting after an overnight fast and after an acute water-load test performed before oxcarbazepine exposure and after maintenance on the medication for 3 weeks. Before oxcarbazepine exposure, the percentage of water load excreted was normal as both groups excreted more than 80% of the administered water load. After the intake of oxcarbazepine, the water load resulted in a reduction of the serum sodium and free water clearance without a concomitant increase in the arginine vasopressin serum levels. Most subjects in both groups failed to excrete 80% or more of the water load, suggesting that the effect of oxcarbazepine is physiological. We found that, after the water load, serum sodium and free water clearance were diminished in both groups without a concomitant increase in the arginine vasopressin serum levels. These findings indicate that oxcarbazepine-induced hyponatremia is not attributable to the syndrome of inappropriate secretion of antidiuretic hormone. Possible mechanisms include a direct effect of oxcarbazepine on the renal collecting tubules or an enhancement of their responsiveness to circulating antidiuretic hormone.

Current issues in the identification and management of bipolar spectrum disorders in 'special populations'

Bipolar disorder is a common, lifelong condition that can present during childhood, adolescence, adulthood or later in life. It may occur alone but, more frequently, is complicated by comorbid psychiatric and medical disorders. As such, bipolar disorder presents in many different special populations, each of which warrants specific considerations of diagnosis, treatment and management. This review summarizes common issues concerning recognition of bipolar disorder, particularly in younger patients, discusses the prevalence and treatment of anxious disorder and addictive comorbidity, and considers bipolar disorder in the institutionalized and forensic populations. Treatment options and the supporting evidence are discussed.