Absorption and elimination of bismuth from oral doses of tripotassium dicitrato bismuthate

The pharmacokinetics of bismuth subcitrate were studied in plasma and urine under conditions of single and multiple dosing (28-56 days) using atomic absorption technique. Single dose plasma pharmacokinetics showed peak concentrations of 5.5-57.5 micrograms.l-1 (mean = 24.7 micrograms.l-1), reached between 30 and 60 min post dosing with an apparent biphasic elimination pattern. Multiple dose studies showed a continuing rise in plasma concentration and urine excretion rate reaching apparent steady-state levels over 7-29 days (mean = 18 days). Washout studies in 6 individuals reciprocated accumulation. Maximum equilibrated plasma levels of 7.6-58.3 micrograms.l-1 (mean = 38.3 micrograms.l-1) were well below those associated with encephalopathy. The half-life of bismuth elimination was 20.7 days. Present patterns of intermittent dosing with bismuth are unlikely to be associated with bismuth accumulation despite slow accumulation and elimination.