AbstractThe 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<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
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