Prolonged respiratory depression was noticed after termination of anesthesia. in a patient with severe. eclampsia who had been treated with magnesium sulfate. 1) Magnesium sulfate is an anticonvulsant the most widely used drug in patients with toxemia of pregnancy. 2) The site of action of magnesium sulfate is the neuromuscular junction of skeletal muscle rather than the central nervous system. 3) Magnesium sulfate should be used after careful evaluation of knee jerk, urinary output and respiratory rate. Serum magnesium levels should also be monitored. 4) The respiratory depression in this ease was considered to be the cumulative effect of magnesium sulfate due to oliguria.