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J.Health Sci., 45(6), 391-400, 1999
Disposition of Sodium and Potassium [14C]-Benzoate (BA) Orally Administered to Rats[in Japanese]
Hideo Kurebayashi,* Terue Takahashi, Nahoko Kaniwa, and Atsushi Takahashi
National Institute of Health Sciences, 1-18-1 Kamiyoga, Setagaya, Tokyo 158-8501, Japan
The absorption, disposition, metabolism and excretion of sodium [14C]-benzoate (NaBA) and potassium [14C]-benzoate (KBA) was studied after oral administration of low (BA 25.4 mg eq/kg), middle (BA 254 mg eq/kg), and high (BA 1050 mg eq/kg) dosages to male Wistar rats.
Excretion of [14C]-BA derived radioactivity was monitored in the urine and feces, and as exhaled [14CO2] from 0 to 48 h.
The tissue distribution of the radioactivity of NaBA was similar to that of KBA.
At 6 h after administration, more than a half of the radioactivity remained in rat at high dosage and 3 - 7% of the radioactivity remained in rats at low and middle dosages of NaBA and KBA.
Relatively high concentration of the radioactivity remained in the stomach, intestine, kidney and liver.
At 48 h after administration, less than 0.7% of the radioactivity remained in rat at low, middle and high dosages of NaBA and KBA.
At all dosages of NaBA and KBA, more than 96.8% of the radioactivity was excreted in the urine within 48 h and that by the other routes were very low.
The major urinary metabolite of BA was hippuric acid (HA).
The higher doses of BA has delayed Tmax and the urinary excretion, and increased Cmax and the concentration of BA in the serum.
AUC and tissue distribution were not linearly related to the administered dose.
The dose effects of BA suggest the saturation of elimination, probably caused by the saturation of the metabolic pathway of BA to HA over middle dosage.
Blood levels of the radioactivity monitored during 48 h were applied to one compartment model with the first-order absorption and Michaelis-Menten elimination.
There was no significant difference between NaBA and KBA in the absorption, distribution, metabolism and excretion.
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