Pharmacokinetics
Absorption:
One pharmacokinetic study found that administration of various ginkgo extracts resulted in median maximum concentrations of bilobalide, ginkgolide A, and ginkgolide B of 3.53-26.85 ng/mL, 3.62-16.44 ng/mL, and 1.38-9.99 ng/mL, respectively. Another pharmacokinetic study using the specific ginkgo leaf extract EGb 761 found that the bioavailability of ginkgolides A and B was greater than 80%, that of bilobalide was 70%, while that of ginkgolide C was very low .
Elimination:
In humans, the elimination rate constant for the ginkgo constituents quercetin and kaempferol are 0.37/hr and 0.30/hr, respectively. Quercetin and kaempferol were excreted in the urine mainly as glucuronides. A pharmacokinetic study using the specific ginkgo leaf extract EGb 761 found that the half-lives of ginkgolides A and B and bilobalide were 4, 6, and 3 hours, respectively, and the amounts of each excreted unchanged in the urine were approximately 70%, 50%, and 30%, respectively.