Question

A patient has been taking two Mag-Ox tablets daily (magnesium oxide, MgO, 400 mg/tablet), but he will now be receiving all of his daily magnesium as part of a 2-hour infusion instead. What should be the infusion rate in mL/min of a solution of 5% dextrose and 0.45% sodium chloride with 10% w/v magnesium chloride hexahydrate (MgCl2 * 6H2O) so that the patient receives the same number of milliequivalents of magnesium in a 2-hour infusion? Answer = 0.33 mL/min (Range 0.31 to 0.34 mL/min), please show how this question is solved.

Answer 1

Magnesium Oxide 400mg two times a day is 800mg.

10% w/v Magnesium Chloride Hexahydrate of 800 mg with 40 ml of 5% dextrose and 0.45% sodium chloride

1 hour = 60 minutes

ml per minute = ml per hour $\div$ 60

40ml for 2 hours is divided to 20 ml for 1 hour

= 20 $\div$ 60

= 0.33 ml/minute