Magnesium Sulfate Versus 5% Dextrose With Treatment Resistant Depression

The proposed study is a 1-week, randomized, double-blind, placebo-controlled, trial to evaluate the efficacy of an IV infusion of magnesium sulfate on symptoms of treatment resistant mild and moderate depression in 20 males and females (21-70 years of age). Participants will be assessed at screening/baseline, day 1, day 2, day 7, and day 8. Each subject will be randomized in a double-blind fashion to receive either IV infusion of magnesium sulfate or 5% dextrose followed by a washout period of 5 days then crossover to receive either IV infusion of 5% dextrose or magnesium sulfate.