The effect of peripartum magnesium on maternal mood: can a commonly used NMDA antagonist reduce postpartum depressive symptoms?

Abstract: Most current pharmacologic treatments for major depressive disorder target the monoaminergic system. Symptomatic relief lags weeks behind therapy initiation and only about a third of patients achieve sustained remission.1,2 Promising recent research has focused on N-methyl-D-aspartate (NMDA) receptor antagonists. A prototype of NMDA antagonists is ketamine, which is sometimes used at higher doses in the induction of general anesthesia. Randomized studies have shown that low doses of ketamine rapidly alleviate depressive symptoms within hours.3-5 Furthermore, the effects of a single infusion of ketamine can lead to alleviation of depressive symptoms for weeks in some patients.6 Magnesium is also an NMDA receptor antagonist and may have similar antidepressant effects. Epidemiologic data support this possibility. Patients with refractory depression have lower central nervous system magnesium levels and case reports of successful use of magnesium for treatment or prophylaxis of depression have been published.7 Yet, an exploration of the impact of intravenous magnesium on depressive symptoms in late pregnancy and early postpartum has not been published. Magnesium infusions are used clinically in obstetrics to prevent seizures in women with preeclampsia. Whether these supra-physiologic doses given in the peripartum period can reduce symptoms or potentially prevent postpartum depression remains to be studied.