Magnesium supplementation: pharmacokinetics in cardiac surgery patients with normal renal function

Abstract Background Intravenous magnesium is routinely administered in intensive care units (ICU) to treat arrhythmias after cardiothoracic surgery. There are no data on the pharmacokinetics of continuous magnesium infusion therapy. Objective To investigate the pharmacokinetics of continuous magnesium infusion, focusing on serum and urinary magnesium concentration, volume of distribution and half-life. Methods We administered a 10 mmol bolus of magnesium-sulfate followed by a continuous infusion of 3 mmol/h for 12 h in twenty cardiac surgery patients. We obtained blood and urine samples prior to magnesium administration and after one, six, and 12 h. Results Median magnesium levels increased from 1.09 (IQR 1.00–1.23) mmol/L to 1.59 (1.45–1.76) mmol/L after 60 min (p  Conclusion Combined bolus and continuous magnesium infusion therapy leads to a significant and stable increase in magnesium serum concentration despite increased renal excretion and redistribution.