Hyponatraemia and carbamazepine intoxication

Serum Levels of Valproic Acid and Carbamazepine Do Not Correlate Well with End-Organ Dysfunction

BACKGROUND

Serum levels of anticonvulsants are commonly ordered; however, the clinical utility of these laboratory tests is unclear. Clarifying the significance of anticonvulsant drug levels is essential to allow physicians to make appropriate management decisions. We aimed to determine to what extent elevated serum levels of valproic acid (VPA) and carbamazepine (CBZ) correlate with laboratory indications of end-organ dysfunction.

METHODS

We reviewed a consecutive sample of patients 0-18 years of age who, over a 2-year period, had at least one blood collection in which (1) serum [VPA] or [CBZ] was tested; and (2) at least one of the following tests was performed: alanine aminotransferase (ALT), aspartate aminotransferase (AST), platelets, white blood cells (WBC), ammonia, sodium.

RESULTS

913 and 300 blood collections met criteria for VPA and CBZ, respectively. A slight increased frequency of having any abnormal laboratory value for elevated [VPA] compared to low/normal [VPA] was observed (p = 0.02; relative risk 1.27), while there was no difference in frequency of having any abnormal lab value for CBZ, nor were there significant differences for the individual lab values. When ALT and AST were plotted against [VPA] and [CBZ], no significant correlation was observed.

CONCLUSION

Serum [VPA] and [CBZ] are poor indicators of risk for drug-induced end-organ dysfunction. There are likely other, individualized risk factors that explain why certain patients develop adverse effects from these medications.

Antiepileptic drugs-induced hyponatremia: Review and analysis of 560 hospitalized patients

Recent evidence suggests that eslicarbazepine acetate (ESL) might be an appropriate alternative to carbamazepine (CBZ) and oxcarbazepine (OXC) due to its better safety profile. Hyponatremia may be one of the limiting safety problems in CBZ and OXC whereas it has been indicated that ESL is less sensitive for the adverse event. Since our clinical experience is different we investigated the incidence of hyponatremia in 560 consecutive adult inpatients treated at our center in 2015 by reviewing their medical records. Only CBZ, OXC and ESL were associated with hyponatremia. The incidence of hyponatremia induced by ESL was not statistically different from that induced by OXC (43% of patients with OXC and 33% with ESL, p > 0.05). Both were associated with hyponatremia more often than CBZ (16%). OXC-induced hyponatremia was dose-related, ESL-induced hyponatremia was not. Furthermore, both OXC- and ESL-induced hyponatremia occurred particularly often in elderly epilepsy patients. Thus, for elderly patients, both OXC and ESL should be considered with caution.

Hyponatremia induced by antiepileptic drugs in patients with epilepsy

INTRODUCTION

Hyponatremia induced by antiepileptic drugs (AEDs) has not received sufficient attention in patients with epilepsy. Areas covered: We reviewed articles between 1966 and 2015 about hyponatremia as an adverse effect of AEDs in patients with epilepsy. The incidence, clinical symptoms, onset times of AEDs-induced hyponatremia are discussed in detail, as are the risk factors associated with AEDs-induced hyponatremia and mechanisms underlying its development. We also briefly describe strategies for treating AED-induced hyponatremia. Expert opinion: Carbamazepine and oxcarbazepine are the most common AEDs which induce hyponatremia in patients with epilepsy. Recently, other AEDs, such as eslicarbazepine, sodium valproate, lamotrigine, levetiracetam and gabapentin have also been reported to cause hyponatremia. Understanding the risk associated with AED-induced hyponatremia and taking effective measures to combat serum sodium imbalance induced by AED therapy are necessary.

Drug-induced syndrome of inappropriate antidiuretic hormone secretion. Causes, diagnosis and management

Hyponatraemia is common among the elderly, and may be caused by physiological changes, disease processes or drugs. About half of elderly patients with hyponatraemia have features typical of the syndrome of inappropriate antidiuretic hormone secretion (SIADH). It is important to establish whether drugs are the cause, as this is easily remediable. The clinical manifestations of SIADH are predominantly attributable to hyponatraemia and serum hypo-osmolality. The severity of the signs and symptoms depends on the degree of hyponatraemia and the rapidity with which the syndrome develops. Although a growing number of drugs have been reported to produce SIADH, most published reports concern vasopressin and its analogues, thiazide and thiazide-like diuretics, chlorpropamide, carbamazepine, antipsychotics, antidepressants and nonsteroidal anti-inflammatory drugs. Old age is a risk factor for SIADH following the use of many of these drugs. The use of these drugs in combination, excessive fluid intake and other underlying conditions that limit free water excretion increase the risk. Drug-induced SIADH usually resolves following cessation of the offending agent(s). Additional measures are required in patients with symptomatic hyponatraemia, including fluid restriction and intravenous sodium chloride and/or furosemide (frusemide) therapy. Careful monitoring is essential, with particular attention paid to the rate and extent of correction of the hyponatraemia.

Review of carbamazepine-induced hyponatremia

1. Carbamazepine (CBZ), a commonly prescribed medication in psychiatry and neurology, produces deleterious side effects with an incidence rate ranging from 33-50%; although most of these side effects are mild, transient, and reversible. CBZ-induced hyponatremia is a moderately well described side effect and may be responsible for some of the more highly reported signs and symptoms associated with CBZ adverse effects. 2. Data from case reports and clinical studies are examined to ascertain the characteristics of CBZ-induced hyponatremia. Predisposing risk factors such as: age, dosage/level of CBZ, and polypharmacy have been explored in numerous clinical studies; however, minimal consensus has been found regarding both dosage/level of CBZ and polypharmacy as a predisposing risk factor, whereas age is most probably not a predisposing risk factor in CBZ-induced hyponatremia. 3. Mechanistic studies, both clinical and basic science, also fail to acknowledge the mechanism for the antidiuretic effect of CBZ. The most probable mechanism involves an alteration in either the sensitivity or set point of the osmoreceptor.

Hyponatremic coma under oxcarbazepine therapy

Oxcarbazepine (OXC) is considered to be a promising new antiepileptic drug with similar efficacy and better tolerability compared to carbamazepine (CBZ). However, hyponatremia is supposed to occur even more often than with CBZ. We report on a patient who developed hyponatremic coma under OXC with a serum sodium level of 115 mmol/l, the second published case of OXC-induced hyponatremia with serious clinical adverse effects.

Oxcarbazepine-induced hyponatremia, a cross-sectional study

In order to estimate the frequency of hyponatremia in patients treated with oxcarbazepine (OxCZ), a cross-sectional study was carried out. 21 of 41 patients being treated with the drug were found to be hyponatremic (serum sodium levels less than 135 mmol/l). None was found to be hypernatremic (serum sodium levels greater than 145 mmol/l). A non-significant trend towards increasing frequency of hyponatremia with increasing age was observed. Patients treated with dosages above 30 mg/kg/day had a significantly higher risk of becoming hyponatremic.

Hyponatremia induced by oxcarbazepine

A case of hyponatremia is presented with water intoxication due to treatment with oxcarbazepine (OxCZ). The patient was admitted because of exceeding dullness and increasing seizures. Low values for serum sodium and osmolality were found. Simultaneously with the reduction in OxCZ, values of sodium and osmolality increased, normalizing on discontinuation of the drug, and the exceeding tiredness as well as the generalized seizures disappeared. Low values of arginine-vasopressin were found, suggesting that the mode of action of OxCZ was directly or indirectly at the level of the kidney.