Recurrent hyponatremia associated with fluoxetine and paroxetine

Psychotropics and hyponatraemia

Hyponatraemia is usually defined as a serum sodium concentration below 135 mmol/1. The condition is rarely symptomatic until serum sodium falls below 120 mmol/1 and symptoms are more usually associated with values around 110 mmol/1. These symptoms include confusion and restlessness, progressing to drowsiness, myoclonic jerks, generalised convulsions and eventually coma. In a general hospital population about 1% of patients develop hyponatraemia (Rutsky, 1992), whereas in psychiatric patients the prevalence has been reported to range from 3.3% to 12.2% (Ohsawa et al, 1992).

Citalopram-induced SIADH in a hypertensive patient on salt restricted diet

Hyponatraemia is a very rare but potentially fatal complication of SSRIs and citalopram therapy, especially during the first weeks of treatment and for those who concomitantly use medications known to cause hyponatraemia. We present a 54-year-old hypertensive female patient who was admitted to the hospital with drowsiness, paresthesia, fatigue, nausea, vomiting and visual hallucinations and who was diagnosed to have syndrome of inappropriate secretion of antidiuretic hormone (SIADH) due to citalopram. All her presenting symptoms disappeared after discontinuation of citalopram therapy, fluid restriction and a careful hypertonic saline infusion. This case suggests that SIADH may develop among hypertensive patients, especially when they use diuretics or follow a salt restricted diet.

Hyponatremia associated with selective serotonin-reuptake inhibitors in older adults

OBJECTIVE

To review the incidence, risk factors, mechanism, times of onset and resolution, and treatment of hyponatremia associated with selective serotonin-reuptake inhibitors (SSRIs).

DATA SOURCES

An English-language literature search was conducted using MEDLINE (1966-December 2005) using the search terms selective serotonin-reuptake inhibitor, hyponatremia, syndrome of inappropriate secretion of antidiuretic hormone, citalopram, escitalopram, fluoxetine, fluvoxamine, paroxetine, and sertraline. Additional references were identified by reviewing bibliographies of articles retrieved.

STUDY SELECTION AND DATA EXTRACTION

Relevant data were extracted from published reports, letters, and studies of humans with hyponatremia and/or syndrome of inappropriate secretion of antidiuretic hormone (SIADH) secondary to SSRIs. All articles identified from data sources were reviewed for relevant information. Applicable information was included in this review.

DATA SYNTHESIS

Numerous case reports, observational studies, and case-controlled studies, as well as one prospective clinical trial, have reported hyponatremia associated with SSRI use, with the incidence varying from 0.5% to 32%. Risk factors for the development of hyponatremia with SSRIs include older age, female gender, concomitant use of diuretics, low body weight, and lower baseline serum sodium concentration. In published reports, hyponatremia developed within the first few weeks of treatment and resolved within 2 weeks after therapy was discontinued. The mechanism by which SSRIs cause hyponatremia is thought to be secondary to development of SIADH. Treatment of isovolemia hypotonic hyponatremia associated with SSRI use includes water restriction and mild diuresis with a loop diuretic. More severe cases may be treated with higher doses of loop diuretics and hypertonic saline. There have been few reports of rechallenge with the same or another SSRI or substitution of another agent from a different therapeutic class. In some, but not all, cases hyponatremia recurred.

CONCLUSIONS

Practitioners should be on the alert for this potentially life-threatening adverse event, especially in older adults with other risk factors for developing hyponatremia.

Delayed recurrent SIADH associated with SSRIs

BACKGROUND

Depression is a common problem in elderly patients and is frequently treated with selective serotonin-reuptake inhibitors (SSRIs).

OBJECTIVE

To report a case of delayed recurrent hyponatremia after switching from one SSRI to another.

CASE SUMMARY

An 87-year-old depressed woman began treatment with fluvoxamine. One week later, she was diagnosed with hyponatremia, most likely syndrome of inadequate antidiuretic hormone. Following discontinuation of fluvoxamine, the serum sodium concentration normalized. Later, she began treatment with paroxetine. Sixteen months after initiating paroxetine, she developed symptomatic recurrent hyponatremia. After paroxetine was discontinued, the sodium concentration normalized.

DISCUSSION

In this case, unlike those previously reported, hyponatremia recurred 16 months after a different SSRI was initiated. The Naranjo probability scale indicates a probable relationship between recurrent hyponatremia and paroxetine. The mechanism of SSRI-induced hyponatremia is multifactorial.

CONCLUSIONS

This case illustrates that replacement of one SSRI with another can cause delayed, recurrent hyponatremia in elderly patients. Plasma sodium concentrations must be monitored, not only in the first weeks of treatment, but throughout the full course.

Depression in epilepsy: etiology, phenomenology, and treatment

A history of depression or depressive symptomatology has been reported in up to two-thirds of patients with medically intractable epilepsy, whereas community studies have demonstrated affective disorder only in a quarter of these patients. Depression has been reported peri- and interictally. However, differentiation may be difficult in patients with frequent seizures. Most authors have found no correlation between depression and epilepsy variables. However, complex partial seizures, especially of temporal lobe origin, appear to be etiologic factors, particularly in men with left-sided foci. Depression is also more common in patients treated with polytherapy especially with barbiturates, phenytoin, and vigabatrin. Depression has also been described de novo after temporal lobectomy. Psychosocial factors also play a part, but underlying risk factors (e.g., genetic, endocrine and metabolic) may explain the increased rates of depression in people with epilepsy compared to those with other neurologic and chronic medical conditions. The depression appears to be endogenous. Patients tend to exhibit fewer neurotic traits and more psychotic symptoms such as paranoia, delusions, and persecutory auditory hallucinations. Treatment approaches include psychotherapy, rationalization of antiepileptic drug medication, antidepressant treatment, and ECT. The tricyclic and related antidepressants appear to be epileptogenic, especially in people at high risk (personal or family history of seizures, abnormal pretreatment EEG, brain damage, alcohol or substance abuse/withdrawal and concurrent use of CNS-active medication). Seizures tend to occur early in treatment or after dose increments, especially if rapidly titrated. There is little evidence that the newer antidepressants, e.g., selective serotonin reuptake inhibitors, moclobemide, venlafaxine, or nefazodone are more epileptogenic than placebo.

Severe life-threatening hyponatremia during paroxetine therapy

Hyponatremia secondary to the syndrome of inappropriate secretion of antiduretic hormone (SIADH) is an uncommon complication of treatment with the antidepressants the selective serotonin reuptake inhibitors (SSRIs). These effective anti-depressant agents are becoming widely used because of their favorable side effect profile and their safety in overdose. Although most reports have implicated fluoxetine in causing hyponatremia, there have also been a few reports of hyponatremia associated with paroxetine. We describe an elderly patient with severe life-threatening hyponatremia in association with paroxetine therapy. The present case and the others previously reported emphasize the need for greater awareness of the development of this serious and potentially fatal complication, and suggest that serum sodium concentration should be measured periodically in elderly patients soon after they start taking any agent of the SSRIs, especially during the first 2 to 4 weeks of treatment.

Selective serotonin reuptake inhibitors and hyponatraemia: review and proposed mechanisms in the elderly

The association between selective serotonin reuptake inhibitors (SSRIs) and hyponatraemia has been well documented, the elderly appearing to be at greatest risk. An analysis of data of hyponatraemia in the elderly using SSRIs from all published cases and from the Committee on Safety of Medicines found that the mean time to detection was about 3 weeks after commencing SSRIs. A wide range of time to detection (1-253 days) and non-specific symptoms suggest hyponatraemia is detected by chance rather than being specifically looked for. In the elderly there are physiological changes, a high prevalence of medical illnesses and concomitant drug use, which may precipitate hyponatraemia. Together with a risk of altered water regulation in psychiatric illness this may account for the particular susceptibility of the elderly to hyponatraemia whilst using SSRIs.

Hyponatraemia associated with the use of selective serotonin re-uptake inhibitors

OBJECTIVE

The aim of this study is to examine the frequency and severity of hyponatraemia in a psychogeriatric inpatient population taking selective serotonin re-uptake inhibitors (SSRIs).

METHOD

Casenotes for 1 year were reviewed and 53 patients with 55 admissions were identified. Eighteen were treated with fluoxetine and 37 with paroxetine. Five (28%) of the patients on fluoxetine and eight (22%) on paroxetine were, or became, hyponatraemic.

RESULTS

The SSRI was discontinued in two symptomatic patients. Serum sodium returned to normal in nine patients maintained on the SSRI. Two patients maintained on an SSRI remained hyponatraemic but asymptomatic.

CONCLUSIONS

Hyponatraemia may be a relatively common early asymptomatic side effect of SSRIs, especially in older women. Serum sodium should be measured before commencing an SSRI and monitored during the first month. Any patient who exhibits symptoms of hyponatraemia, or whose depression apparently worsens, while on an SSRI must have their serum sodium measured. Discontinuation of the SSRI may be avoidable if serum sodium levels can be closely monitored.

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.