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.
Adult Biological Availability