title: MgCaCO3 versus CaCO3 in peritoneal dialysis patients--a cross-over pilot trial.
abstract: BACKGROUND
  Despite adverse effects such as constipation, vascular calcification, and hypercalcemia, calcium-based salts are relatively affordable and effective phosphate binders that remain in widespread use in the dialysis population. We conducted a pilot study examining whether the use of a combined magnesium/calcium-based binder was as effective as calcium carbonate at lowering serum phosphate levels in peritoneal dialysis (PD) patients.
  
  
  METHODS
  This was a cross-over, investigator-masked pilot study in which prevalent PD patients received calcium carbonate alone (200 mg calcium per tablet) or calcium magnesium carbonate (100 mg calcium, 85 mg magnesium per tablet). Primary outcome was serum phosphate level at 3 months. Analysis was as per protocol.
  
  
  RESULTS
  Twenty patients were recruited, 17 completed the study. Mean starting dose was 11.35 ± 7.04 pills per day of MgCaCO3 and 9.00 ± 4.97 pills per day of CaCO3. Mean phosphate levels fell from 2.13 mmol/L to 2.01 mmol/L (95% confidence interval (CI): 1.76 - 2.30, p = 0.361) in the MgCaCO3 group, and 1.81 mmol/L (95% CI: 1.56 - 2.0, p = 0.026) in the CaCO3 alone group. Six (35%) patients taking MgCaCO3 and 9 (54%) taking CaCO3 alone achieved Kidney Disease Outcomes Quality Initiative (KDOQI) serum phosphate targets at 3 months. Diarrhea developed in 9 patients taking MgCaCO3 and 3 taking CaCO3. Serum magnesium exceeded 1.4 mmol/L in 5 patients taking MgCaCO3 while serum calcium exceeded 2.65 mmol/L in 3 patients receiving CaCO3. When compared to the initial dose, the prescribed dose at 3 months was reduced by 44% (to 6.41 tablets/day) in the MgCaCO3 group and by 8% (to 8.24 pills per day) in the CaCO3 alone group.
  
  
  CONCLUSIONS
  Compared with CaCO3 alone, the preparation and dose of MgCaCO3 used in this pilot study was no better at lowering serum phosphate levels in PD patients, and was associated with more dose-limiting side effects.
authors.affiliation: Health Sciences University of Mongolia, Ulaanbaatar, Mongolia; and The Scarborough General Hospital, Scarborough, Ontario, Canada.
authors.forename: Baigalmaa
authors.initials: B
authors.lastname: Evsanaa
authors.affiliation: Health Sciences University of Mongolia, Ulaanbaatar, Mongolia; and The Scarborough General Hospital, Scarborough, Ontario, Canada.
authors.forename: Irene
authors.initials: I
authors.lastname: Liu
authors.affiliation: Health Sciences University of Mongolia, Ulaanbaatar, Mongolia; and The Scarborough General Hospital, Scarborough, Ontario, Canada.
authors.forename: Babak
authors.initials: B
authors.lastname: Aliazardeh
authors.affiliation: Health Sciences University of Mongolia, Ulaanbaatar, Mongolia; and The Scarborough General Hospital, Scarborough, Ontario, Canada.
authors.forename: Sara
authors.initials: S
authors.lastname: Mahdavi
authors.affiliation: Health Sciences University of Mongolia, Ulaanbaatar, Mongolia; and The Scarborough General Hospital, Scarborough, Ontario, Canada.
authors.forename: Gursarn
authors.initials: G
authors.lastname: Bajwa
authors.affiliation: Health Sciences University of Mongolia, Ulaanbaatar, Mongolia; and The Scarborough General Hospital, Scarborough, Ontario, Canada.
authors.forename: Jerry
authors.initials: J
authors.lastname: Gula
authors.affiliation: Health Sciences University of Mongolia, Ulaanbaatar, Mongolia; and The Scarborough General Hospital, Scarborough, Ontario, Canada.
authors.forename: Michelle
authors.initials: M
authors.lastname: Tam
authors.affiliation: Health Sciences University of Mongolia, Ulaanbaatar, Mongolia; and The Scarborough General Hospital, Scarborough, Ontario, Canada.
authors.forename: Elena
authors.initials: E
authors.lastname: Sze
authors.affiliation: Health Sciences University of Mongolia, Ulaanbaatar, Mongolia; and The Scarborough General Hospital, Scarborough, Ontario, Canada.
authors.forename: Janet M
authors.initials: JM
authors.lastname: Roscoe
authors.affiliation: Health Sciences University of Mongolia, Ulaanbaatar, Mongolia; and The Scarborough General Hospital, Scarborough, Ontario, Canada.
authors.forename: Paul Y
authors.initials: PY
authors.lastname: Tam
authors.affiliation: Health Sciences University of Mongolia, Ulaanbaatar, Mongolia; and The Scarborough General Hospital, Scarborough, Ontario, Canada.
authors.forename: Tabo
authors.initials: T
authors.lastname: Sikaneta
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000368:Aged; D002119:Calcium Carbonate / Q000008:administration & dosage*; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D054559:Hyperphosphatemia / Q000097:blood / Q000188:drug therapy*; D008274:Magnesium / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D010349:Patient Compliance; D010530:Peritoneal Dialysis / Q000009:adverse effects* / Q000379:methods; D010865:Pilot Projects; D018570:Risk Assessment; D016037:Single-Blind Method; D016896:Treatment Outcome
chemical_list: C005479:magnesium carbonate; D002119:Calcium Carbonate; D008274:Magnesium
keywords: Phosphate-binders; adverse effects; compliance rates; magnesium calcium carbonate