Comparison of plasma bismuth levels after oral dosing with basic bismuth carbonate or tripotassium dicitrato bismuthate

In 20 healthy subjects plasma bismuth concentration was measured after single oral doses of basic bismuth carbonate or tripotassium dicitrato bismuthate. The drugs were administered in the fasted state or immediately after ingestion of a standard breakfast. After basic bismuth carbonate, plasma bismuth rose to concentrations between 0.7 and 2.6 micrograms/L in the fasted state, while after the meal the maximal level was only 1.3 micrograms/L. In contrast to these very low levels after basic bismuth carbonate, the administration of tripotassium dicitrato bismuthate was paralleled by an increase of plasma bismuth to concentrations between 15 and 232 micrograms/L with a mean peak value of 64 +/- 15.3 (S.E.M.) micrograms/L in the fasted state. Postprandial ingestion of tripotassium dicitrato bismuthate attenuated the peak concentrations to 10.9 +/- 6.3 micrograms/L. One subject, however, had a value of 120 micrograms/L. This study demonstrates that basic bismuth carbonate leads to very low plasma bismuth concentrations, which are far below the critical range that might eventually be associated with bismuth neurotoxicity. Therefore this compound can be considered potentially useful for bismuth therapy of gastrointestinal disorders.