Purpose

Calcium is a life saving medicine in the care of parturients. It has many important uses including treatment of hypocalcemia, treatment of magnesium toxicity, prevention of hypocalcemia during blood transfusion (of citrate containing blood products), treatment of hyperkalemia, and others. Recent clinical trials also suggest that calcium given after cord clamping may decrease blood loss in patients undergoing cesarean delivery. 2 FDA approved forms of calcium can be given intravenously: calcium chloride and calcium gluconate. Over the last decade there have been times with drug shortages of either calcium chloride or calcium gluconate. So there have been and likely will continue to be times when one formulation or the other may not be adequately available. Despite the importance of calcium and the frequency in which it is used in parturients, there are no published studies in parturients to determine dose equivalence between calcium gluconate and calcium chloride. In this study the investigators will determine the population pharmacokinetics of calcium gluconate and calcium chloride in parturients and calculate the dose equivalent ratio the two drugs. This will help clinicians select appropriate doses of calcium and provide resilience to the drug supply chain in our era of frequent drug shortages.