Preparation of Magnesium Sulphate and Lidocaine and Set Up

Stock solutions of magnesium sulphate, lidocaine, and magnesium sulphate-lidocaine mix were prepared, filtered, placed in sterile VIAFLEX bags (Baxter Corp., Mississauga ON), and aliquoted into 5 mL sterile BD Luer-Lok plastic syringes (VWR International LLC, Mississauga ON). The syringes (Kendall Pharmaceuticals, Charlotte, NC) were capped. As outlined in Appendix 1, one half of the syringes (225 syringes) were stored in a lightless container at 25°C and the remainder were stored in a lightless humidified incubator set at 40°C.

The concentrations and volumes of each mixture are summarized in Table 1. A mixture of 540 mL of commercially available magnesium sulphate 50% USP (Pharmaceutical Partners of Canada Inc., Richmond Hill ON) and 54 mL of lidocaine HCl 2% (Alveda Pharmaceuticals Inc., Toronto ON) was prepared and labelled as CM50CL2. Magnesium sulphate heptahydrate USP (610 g) (Medisca Pharmaceuticals Inc., Richmond BC) was dissolved in sterile water for injection (Baxter Corp., Mississauga ON) to a volume of 1 L and labelled as MS. Magnesium sulphate heptahydrate USP (543.5 g) was dissolved in SWI. Lidocaine HCl 2% (108.7 mL) was added to the solution. The volume of the solution was adjusted to 1 L with SWI; the sample was labelled as MSCL2. Commercially available magnesium sulphate 50% USP, labelled as CM50, and commercially available lidocaine HCl 2%, labelled as CL2, were used as controls.

Products and controls prepared