Pharmacokinetics of rebaudioside A and stevioside after single oral doses in healthy men.

This randomized, double-blind, cross-over study assessed the comparative pharmacokinetics of steviol and steviol glucuronide following single oral doses of rebaudioside A and stevioside in healthy adult male subjects. Steviol glucuronide appeared in the plasma of all subjects after administration of rebaudioside A or stevioside, with median tmax values of 12.0 and 8.00h post-dose, respectively. Steviol glucuronide was eliminated from the plasma, with similar t1/2 values of approximately 14h for both compounds. Administration of rebaudioside A resulted in a significantly (approximately 22%) lower steviol glucuronide geometric mean Cmax value (1472ng/mL) than administration of stevioside (1886ng/mL). The geometric mean AUC0-t value for steviol glucuronide after administration of rebaudioside A (30,788ngh/mL) was approximately 10% lower than after administration of stevioside (34,090ngh/mL). Steviol glucuronide was excreted primarily in the urine of the subjects during the 72h collection period, accounting for 59% and 62% of the rebaudioside A and stevioside doses, respectively. No steviol glucuronide was detected in feces. Pharmacokinetic analysis indicated that rebaudioside A and stevioside underwent similar metabolic and elimination pathways in humans with steviol glucuronide excreted primarily in the urine and steviol in the feces. No safety concerns were noted as determined by reporting of adverse events, laboratory assessments of safety or vital signs.