June 2007

rTMS: Inferior to ECT?
Repetitive transcranial magnetic stimulation (rTMS) is not as efficacious as electroconvulsive therapy (ECT) in patients referred for ECT.

Psychotropics and Fracture Risk
Patients (especially elderly ones) taking psychiatric medications are at increased risk for fractures.

Riluzole Augmentation for Depression
Preliminary evidence suggests riluzole (Rilutek) may be helpful in treating mood and anxiety disorders.

CBT Beats Zopiclone for Insomnia in Elderly
Cognitive behavioral therapy (CBT) was superior to zopiclone (Ambien) for chronic primary insomnia.

Alternative Medicines Are Commonly Used
Surveys show alternative medicines used by more than half of US population.

Hyponatremia with Antidepressants
Hyponatremia reported in patients treated with escitalopram (Lexapro) or duloxetine (Cymbalta).

In Brief
Dosing Strategies for Risperidone Long-Acting Injection; Deaths Associated with Methadone Treatment for Pain

Prolactin Levels and Associated Side Effects with Risperidone
Initial elevation of prolactin levels with risperidone (Risperdal) returns to normal with long-term treatment.

Mifepristone for Psychotic Depression?
Treatment with mifepristone (Mifeprex) improves psychosis but not depression in patients with psychotic depression.

An NSAID for Schizophrenia?
Adjunctive celecoxib (Celebrex) may be beneficial for treating schizophrenia.

Hyponatremia with Antidepressants

June 2007

Hyponatremia is a known side effect of selective serotonin reuptake inhibitors (SSRIs) (BTP 2004;27:23-24). Covyeou and Jackson present a case involving escitalopram (Lexapro)1 and Krüger and Lindstaedt write of five patients who developed hyponatremia associated with the newest antidepressant, duloxetine (Cymbalta), a norepinephrine-serotonin dual reuptake inhibitor.2

A 75-year-old woman with a history of hypertension and depression came to an emergency room because of confusion.1 Over the course of a week in the hospital, her serum sodium was relatively constant between 129 and 133 mmol/L. Doctors then prescribed escitalopram and donepezil (Aricept). The patient's serum sodium plunged to 116 mmol/L, with urine and serum osmolality suggesting the syndrome of inappropriate antidiuretic hormone secretion (SIADH). Escitalopram was discontinued, and within 5 days, the patient's serum sodium returned to normal.

In a separate report on antidepressant-induced hyponatremia, three women and two men, aged 35 to 70 years, were treated with duloxetine for major depression.2 Duloxetine doses were 90 to 120 mg/day when hyponatremia developed. Associated physical symptoms included fatigue, lethargy, and headache.

In four patients, duloxetine was discontinued. In the fifth patient, it was reduced to 60 mg daily. Treatment also included water and sodium restrictions. Symptoms and abnormal laboratory values resolved within 2 weeks in all cases.

SSRIs have been associated with a threefold higher risk of hyponatremia than other antidepressants.3 The relative risk associated with duloxetine remains to be clarified.

The chances of an SSRI-treated patient developing hyponatremia is highest at the start of treatment and greater in women and older patients. An increase in antidiuretic hormone secretion is the presumed mechanism.

There is no need to routinely monitor serum sodium concentrations in antidepressant-treated patients. However, if confusion, seizures, or other symptoms develop that might be due to decreased serum sodium, order this blood test immediately.

1Covyeou JA, Jackson CW: Hyponatremia associated with escitalopram. N Engl J Med 2007;356:94-95.

2Krüger S, Lindstaedt M: Duloxetine and hyponatremia: A report of 5 cases. J Clin Psychopharmacol 2007;27:101-104.

3Movig KL, Leufkens HG, Lenderink AW, van den Akker VG, Hodiamont PP, Goldschmidt HM, Egberts AC: Association between antidepressant drug use and hyponatraemia: A case-control study. Br J Clin Pharmacol 2002;53:363-369.