title: Pharmacokinetic and pharmacodynamic comparison of two calcium supplements in postmenopausal women.
abstract: This randomized crossover study compared the single-dose bioavailability and effects on parathyroid function of two commercially formulated calcium supplements containing 500 mg of elemental calcium. Twenty-five postmenopausal women underwent three phases of study wherein they each took a single dose of calcium citrate with a standard breakfast (as Citracal 250 mg + D), calcium carbonate (as Os-Cal 500 mg + D), or placebo at 8 a.m. Blood samples were drawn at baseline and hourly for 4 or 6 hours after each dose. Fasting and postload urine samples were also collected. Compared with calcium carbonate, calcium citrate provided a 46% greater peak-basal variation and 94% higher change in area under the curve for serum calcium and a 41% greater increment in urinary calcium. Moreover, the decrement in serum parathyroid hormone concentration from baseline was greater after calcium citrate. In conclusion, calcium citrate is more bioavailable than calcium carbonate when given with a meal.
authors.affiliation: Center for Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas 75390-8885, USA.
authors.forename: H J
authors.initials: HJ
authors.lastname: Heller
authors.forename: L G
authors.initials: LG
authors.lastname: Greer
authors.forename: S D
authors.initials: SD
authors.lastname: Haynes
authors.forename: J R
authors.initials: JR
authors.lastname: Poindexter
authors.forename: C Y
authors.initials: CY
authors.lastname: Pak
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001682:Biological Availability; D002119:Calcium Carbonate / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000494:pharmacology; D019355:Calcium Citrate / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000494:pharmacology; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood; D017698:Postmenopause / Q000378:metabolism*; D012982:Sodium, Dietary / Q000008:administration & dosage
chemical_list: D010281:Parathyroid Hormone; D012982:Sodium, Dietary; D002119:Calcium Carbonate; D019355:Calcium Citrate