title: In vitro and in vivo assessment of the bioavailability of potassium from a potassium tartrate tablet.
abstract: The bioavailability of potassium from orally administered potassium tartrate was evaluated in 20 normal subjects under metabolic balance conditions. Subjects were given 34 mmol potassium (5 tablets of Cal-K) as a divided dose on each of 2 consecutive days. Urinary excretion of potassium, as determined from 24-h urinary collections on the 3 days preceding dosage totalled 192.6 +/- 50.9 mmol (mean +/- S.D., n = 20). It increased significantly (p less than 0.05) to 258.7 +/- 54.2 mmol for the 2 days of dosage and the following day. The difference of 66.1 mmol representing absorbed potassium was close to the 68 mmol potassium given and indicated a bioavailability of potassium in excess of 97 per cent; after correction for creatinine excretion, potassium recovery rose to 99.9 per cent. The dissolution characteristics of the Cal-K tablets were also determined. After dissolution in simulated gastric juice (pH 1.2), 84.4 +/- 10.6 per cent (mean +/- S.D., 6 experiments) was dissolved; after adjustment to pH 7.3, dissolved potassium increased to 91.3 +/- 8.5 per cent. No precipitation or residue formed as a result of the pH change. Both sets of results indicate that potassium from these potassium tartrate tablets is in a highly bioavailable form.
authors.affiliation: College of Pharmacy, University of Saskatchewan, Saskatoon, Canada.
authors.forename: S J
authors.initials: SJ
authors.lastname: Whiting
authors.forename: D K
authors.initials: DK
authors.lastname: Gorecki
authors.forename: D
authors.initials: D
authors.lastname: Jones
mesh_terms: D000328:Adult; D001682:Biological Availability; D003404:Creatinine / Q000652:urine; D005260:Female; D005744:Gastric Acid; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007421:Intestine, Small / Q000378:metabolism; D008297:Male; D011188:Potassium / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000652:urine; D012964:Sodium / Q000652:urine; D012995:Solubility; D013607:Tablets; D013644:Tartrates / Q000008:administration & dosage / Q000493:pharmacokinetics*
chemical_list: D013607:Tablets; D013644:Tartrates; D012964:Sodium; D003404:Creatinine; D011188:Potassium; C029768:tartaric acid