Syndrome of inappropriate secretion of antidiuretic hormone secondary to fluoxetine

Effect of acute paracetamol overdose on changes in serum and urine electrolytes

AIMS

To investigate the effects of acute paracetamol overdose on renal function, serum and urine electrolyte excretion in man.

METHODS

Two studies were performed in patients admitted with paracetamol overdose: a retrospective study examining changes in serum electrolytes, and a prospective study evaluating changes in serum and urine electrolytes. A control group with SSRI overdose was included in the prospective study.

RESULTS

There was a significant dose-dependent relationship between admission (4 h) paracetamol concentration and fall in serum potassium in the retrospective study (P < 0.01) and a significant positive relationship between serum paracetamol at 4 h and fractional excretion of potassium at 12 h postingestion (P < 0.01) in the prospective study. No changes were seen in the control group. No cases developed renal failure.

CONCLUSIONS

Paracetamol overdose is associated with dose-related hypokalaemia, and kaliuresis of short duration (<24 h), suggesting a specific renal effect of paracetamol in overdose perhaps via cyclo-oxygenase inhibition. This effect seems distinct from any nephrotoxic effect of paracetamol.

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.

A review on hyponatremia associated with SSRIs, reboxetine and venlafaxine

Hyponatremia, defined as serum sodium below 135 mmol/l, is a potentially life-threatening condition and was shown to be more frequent in elderly and psychiatric patients. In the last years numerous case reports on SSRI- and venlafaxine-induced hyponatremia were published indicating a higher incidence than previously thought. Only few studies have been performed and the incidence reported varies widely from 4.6/1000 people to 25%. It is still unclear if any single SSRI shows a higher incidence of hyponatremia than the others. Some data suggest that venlafaxine may have a stronger association to hyponatremia than SSRIs. Risk factors include age, female sex, low body mass index, severe physical illness, history of former hyponatremia and co-medications known to induce hyponatremia, especially thiazide diuretics. Symptoms of hyponatremia are usually neuropsychiatric (e.g. restlessness, lethargy, cognitive impairment), and any worsening in psychiatric symptoms in patients with a corresponding risk-profile receiving SSRIs or venlafaxine should give cause to check serum electrolytes. Usually SSRI-induced hyponatremia occurs within approximately 30 days and is reported to improve after withdrawal of the drug. Further controlled studies to confirm the true incidence of hyponatremia due to SSRI or venlafaxine and to define predictors more precisely are needed.

Conduite à tenir concernant le traitement médicamenteux des patients adressés pour chirurgie programmée

This review focuses on potential drug interactions between anaesthetic drugs or techniques and chronic medications in patients scheduled for surgery. The vast majority of therapeutics can be continued until the morning of surgery. However, for some drugs such as ACE inhibitors, there is strong evidence to recommend their discontinuation prior to surgery. When juged necessary, interruption of chronic therapeutic needs to be anticipated and planned. In the other hand, for other drugs such as beta-blockers or L-Dopa, acute withdrawal is associated with documented adverse outcome. As a result, such drugs have to be continuing throughout the operative period. Although a general consensus exists for many medications, there are still controverses as to the management of antithrombotic drugs and some central nervous system agents. Advances in anaesthesia include knowledge on the mechanisms involved in drug interactions, which allows us to improve the preoperative management of chronic therapeutics.

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.

Hyponatraemia and selective serotonin re-uptake inhibitors in elderly patients

Hyponatraemia (serum sodium arbitrarily defined as less than 135 mmol/L) is an increasingly recognised adverse effect of selective serotonin re-uptake inhibitors (SSRIs). Its precise prevalence and incidence in the elderly are hard to determine because of confounding factors including other prescribed medications and medical conditions. Although hyponatraemia has been reported with all SSRIs and venlafaxine, most studies are small, retrospective, limited by confounding variables or are individual case reports. The risk of developing hyponatraemia while on an SSRI seems to increase with age, female, sex, previous history of hyponatraemia and the concomitant use of other medications known to include hyponatraemia. The sodium concentrations of most patients with SSRI associated hyponatraemia return to normal within days to weeks of SSRI withdrawal. A few cases of SSRI rechallenge indicate that hyponatraemia may sometimes be a transient effect with tolerance developing over time. There is an urgent need for controlled, rigorous studies to confirm the extent of the association between SSRIs and hyponatraemia. Older drugs such as tricyclic antidepressants also need systematic study. It remains quite unclear whether any specific SSRI or venlafaxine has a stronger association with hyponatraemia than any other antidepressant drug.

Effect of paroxetine on plasma vasopressin and water load testing in elderly individuals

Hyponatremia sometimes occurs in elderly depressed patients treated wtih a serotonin reuptake inhibitor (SRI). The cause of the hyponatremia is not yet understood. The objective of this study was to determine the effects of paroxetine, an SRI, on osmoregulated release of vasopressin (also termed antidiuretic hormone) in elderly depressed patients with normal serum sodium. Four women and one man ages 61 to 74 years with a major depressive disorder were administered a water load after they had been treated with a therapeutic dose of paroxetine for 3 to 11 months. Three healthy elderly subjects not receiving paroxetine served as controls. Both the patients and the control subjects excreted > 90% of the ingested water and lowered urine osmolality to < 100 mosmol/kg. We conclude that long-term treatment with paroxetine alone does not appear to affect the ability to excrete a water load or appropriately dilute the urine during a water load (both indices of vasopressin function) in a small group of elderly patients without other risk factors for the development of hyponatremia.

The effect of sertraline on routine blood chemistry values

Sertraline is an antidepressant of the selective serotonin reuptake inhibitor (SSRI) class. Although SSRIs are believed to have a milder side effect profile than the tricyclic antidepressants, there are some potentially serious side effects. These include hyponatremia, which has been seen with each of the SSRIs. We reviewed the charts of 246 patients treated with sertraline at a veterans' hospital. We obtained values for each patient's basic chemistry panel (sodium, potassium, chloride, glucose, carbon dioxide, blood urea nitrogen, and creatinine) before and after institution of sertraline therapy. We studied the patients' ages and sertraline doses to see if there was a relationship between any laboratory value changes and these variables. We found no relationship between maximum sertraline dose, age, and changes in routine blood chemistry results with the exception of a small (0.5%) contribution of maximum sertraline dose to variance in serum creatinine levels. Sertraline therapy was not noted to cause any significant changes in serum sodium levels.

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.

Hyponatremia with venlafaxine

OBJECTIVE

To describe a patient with hyponatremia associated with venlafaxine therapy.

CASE SUMMARY

A 92-year old white woman who was receiving venlafaxine for management of depression was found to have hyponatremia. A detailed workup confirmed the diagnosis of syndrome of inappropriate antidiuretic hormone secretion (SIADH). A temporal relationship between initiation of venlafaxine therapy and the onset of hyponatremia indicated it as the probable cause. Venlafaxine was discontinued, and hyponatremia resolved with a few weeks.

DISCUSSION

Hyponatremia has been reported with selective serotonin-reuptake inhibitors (SSRIs). Serotonin has been reported to elevate concentrations of vasopressin in animal models. Venlafaxine is a potent inhibitor of serotonin reuptake and may have adverse effects similar to those of SSRIs.

CONCLUSIONS

We report a case of hyponatremia probably caused by venlafaxine. Awareness of this potential problem would be helpful to clinicians and should be considered in the differential diagnosis of hyponatremia.

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.

Syndrome of inappropriate secretion of antidiuretic hormone in two elderly women with elevated serum fluoxetine

OBJECTIVE

Fluoxetine is widely prescribed for depressed patients. Hyponatremia secondary to inappropriate secretion of antidiuretic hormone has been reported in a few cases associated with routine use of fluoxetine, especially in elderly patients. The mechanism has been postulated to be linked to the inappropriate secretion of antidiuretic hormone. Serum concentrations of antidiuretic hormone and fluoxetine have not been reported in previously published reports.

CASE REPORT

We report two new cases of severe and reversible hyponatremia associated with routine use of fluoxetine therapy in two elderly women. Fluoxetine-induced inappropriate secretion of antidiuretic hormone was confirmed by elevated serum concentrations of antidiuretic hormone and fluoxetine.

The role of sertraline in a patient with recurrent hyponatremia

A 75-year-old female with major depression was admitted to the hospital on two separate occasions for medical problems. During both her hospitalizations she was evaluated by a psychiatrist and diagnosed with a major depressive episode. On both admissions the antidepressant chosen to treat her depression was sertraline. Each time the patient was treated with sertraline she developed significant hyponatremia within 7 days of the initiation of therapy. The case is presented and discussed, with special emphasis on the prior reports of hyponatremia associated with sertraline use, and the treatment alternatives.

Fluoxetine and the syndrome of inappropriate secretion of antidiuretic hormone (SIADH)

OBJECTIVE

To report three new cases of the fluoxetine-induced syndrome of inappropriate secretion of antidiuretic hormone (SIADH).

CLINICAL PICTURE

All three cases occurred in elderly psychiatric inpatients treated for depression with standard doses of fluoxetine within one month of starting the medication. All three patients were clinically symptomatic of SIADH.

TREATMENT

In all three patients the medication was ceased and fluid restriction commenced. One patient required intravenous saline.

OUTCOME

All three patients recovered fully within three weeks. None were rechallenged.

CONCLUSIONS

The symptoms of hyponatraemia due to fluoxetine-induced SIADH may be difficult to distinguish from the symptoms of depression, unless appropriate laboratory investigations are made.

Hyponatraemia and the syndrome of inappropriate antidiuretic hormone secretion (SIADH) induced by psychotropic drugs

The use of psychotropic drugs has been associated with the syndrome of inappropriate antidiuretic hormone secretion (SIADH) in a number of case reports. SIADH is characterised by the sustained release of antidiuretic hormone (ADH) from the posterior pituitary. The patients have a reduced ability to excrete diluted urine, ingested fluid is retained, and the extracellular fluid expands and becomes hypo-osmolar. The cardinal signs are hyponatraemia, serum hypoosmolality and a less than maximally diluted urine. Common symptoms include weakness, lethargy, headache, anorexia and weight gain. These symptoms may be followed by confusion, convulsions, coma and death. The early symptoms are vague and nonspecific, and they may even mimic the symptoms of the psychiatric disorder itself. For antidepressants, the risk of SIADH seems to be highest during the first weeks of treatment. For antipsychotics, the risk seems to be more spread out in time. The causative role of the drug may sometimes be difficult to estimate, as even drug-free psychiatric patients, mostly those with schizophrenia, develop SIADH on the basis of psychogenic polydipsia. Smoking is another factor associated with the development of SIADH, and the risk may also increase with age. The acute treatment of SIADH induced by a psychotropic drug includes discontinuation of the drug as well as restriction of fluid intake. In cases with significant clinical symptoms, infusion of sodium chloride is recommended. After the acute management, it is useful to evaluate the causative role of the drug by performing a water loading test and/or drug rechallenge. If continued treatment with an antidepressant or antipsychotic is indicated, a drug with a different pharmacological profile should be chosen, and the serum sodium levels should be monitored closely. If treatment with the drug that caused SIADH must be continued, concomitant treatment with demeclocycline may reduce the tendency of hyponatraemia.

Fluoxetine. A review of its pharmacodynamic and pharmacokinetic properties, and therapeutic use in older patients with depressive illness

The selective serotonin (5-hydroxytryptamine; 5-HT) reuptake inhibitor fluoxetine is an effective antidepressant in elderly patients. Its efficacy is similar to that of other frequently used antidepressants, such as the tricyclic antidepressants. However, compared with the tricyclic antidepressants, fluoxetine has a more favourable tolerability profile and is less toxic in overdose. It is associated with fewer anticholinergic, cardiovascular and CNS adverse events, but greater numbers of gastrointestinal adverse events than have been reported for the tricyclic antidepressants. This is important in elderly patients who are more at risk of developing central anticholinergic and cardiovascular effects than are younger patients. Therefore, while its position relative to other selective serotonin reuptake inhibitors requires investigation, fluoxetine represents a major advance over tricyclic antidepressant agents in the treatment of elderly patients with depression, predominantly because of its favourable tolerability profile.