Serum magnesium concentrations in patients receiving sodium picosulfate and magnesium citrate bowel preparation: an assessment of renal function and electrocardiographic conduction

Abstract

Background

We performed a post hoc analysis of two clinical trials to assess whether sodium picosulfate and magnesium (Mg ²⁺) citrate (Prepopik ^® [P/MC]), a dual-action bowel preparation for colonoscopy, has an impact on serum Mg ²⁺ levels and cardiac electrophysiology. Although rare, hypermagnesemia has been reported in patients consuming Mg ²⁺-containing cathartics, especially patients who are elderly and have renal impairment.

Methods

Data were analyzed from two prospective, Phase III, randomized, assessor-blinded, active-control, multicenter, pivotal studies that investigated split-dose/day-before P/MC. Serum Mg ²⁺ and creatinine clearance (CrCl) were measured at screening, on the day of colonoscopy, and 24–48 hours, 7 days, and 4 weeks after colonoscopy; electrocardiograms also were obtained at these time points.

Results

In total, 304 patients received split-dose P/MC and 294 patients received day-before P/MC. Only 10% of the patients had serum Mg ²⁺ above the upper limit of normal (1.05 mmol/L) on the day of colonoscopy. There was a slight inverse correlation between CrCl and Mg ²⁺ levels on the day of colonoscopy; however, even at the lowest CrCl, serum Mg ²⁺ remained below clinically significant levels of 2.0 mmol/L. Increases in serum Mg ²⁺ were transient, with levels returning to baseline within 24–48 hours, regardless of renal function. No patients with elevated Mg ²⁺ experienced a corrected QT (QTc) interval >500 milliseconds or a QTc interval increase of ≥60 milliseconds from baseline. P/MC had no impact on PR or QRS interval.

Conclusion

P/MC produces little impact on serum Mg ²⁺ levels with no clinically significant effect on cardiac conduction in patients, including those with mild-to-moderate renal impairment.