The absorption of bismuth from oral doses of tripotassium dicitrato bismuthate

Abstract

Two studies measured plasma concentrations of bismuth during dosing with tripotassium dicitrato bismuthate (De-Noltab). The first study compared 24 h plasma bismuth concentration and urinary bismuth excretion in six patients who had already received 29-131 days (median 47 days) of treatment with De-Noltab 2 b.d., and six healthy subjects who only received De-Noltab 2 b.d. on the day of study. There was a prompt rise in plasma bismuth concentration after each dose of De-Noltabs. The median 24 h integrated plasma bismuth concentration was similar in both groups, but the median 24 h urinary bismuth excretion was 5.4-fold higher in the patients. The second study compared the plasma bismuth concentrations after the first and third doses of De-Noltab 2 b.d. in 16 healthy subjects. The median peak bismuth concentration occurred 30 min (range 15-105 min) post-dosing. The peak plasma bismuth concentration was greater than 50 ng/ml in 14 of the 16 subjects, and greater than 100 ng/ml in nine of the subjects. There was no significant difference in the median integrated 10-h plasma bismuth concentration after the first or third dose of De-Noltabs. The results of these studies confirm that bismuth is absorbed and sequestrated during dosing with De-Noltabs. Bismuth is absorbed rapidly after oral dosing with De-Noltabs, to produce peak plasma bismuth concentrations hitherto considered to be in the range associated with bismuth neurotoxicity.