title: 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Hillmont GI, Flourtown, PA, USA.
authors.forename: Gerald
authors.initials: G
authors.lastname: Bertiger
authors.affiliation: Delaware Valley Nephrology and Hypertension Associates, Philadelphia, PA, USA.
authors.forename: Edward
authors.initials: E
authors.lastname: Jones
authors.affiliation: Ferring Pharmaceuticals Inc., Parsippany, NJ, USA.
authors.forename: David N
authors.initials: DN
authors.lastname: Dahdal
authors.affiliation: Ferring Pharmaceuticals Inc., Parsippany, NJ, USA.
authors.forename: Dennis C
authors.initials: DC
authors.lastname: Marshall
authors.affiliation: Ferring Pharmaceuticals Inc., Parsippany, NJ, USA.
authors.forename: Raymond E
authors.initials: RE
authors.lastname: Joseph
keywords: bowel preparation; hypermagnesemia; renal impairment; sodium picosulfate