Soyselect^® is supported by extensive pharmacokinetics studies performed both in animals (1-4) and humans (5,6). In healthy volunteers the pharmacokinetics of Soyselect^® were evaluated:

in a pilot study after single oral administration

The aim of the study was to evaluate plasma levels of genistein and daidzein achievable after the single oral administration of 400 mg of Soyselect^®, mainly in order to obtain indications about the dosages to be used in subsequent trials. Healthy subjects (25.3±4 years old) received two capsules of 200 mg of Soyselect^® each. Plasma concentration was evaluated over a 12 hour period and excretion over a 24 hour period after the administration.

in a pharmacokinetic study after repeated oral administration

The plasma levels of daidzein and genistein were evaluated in ten healthy volunteers after repeated oral administration of 400 mg of Soyselect® once a day for eight days. The plasma samples were collected at:

day 1 - time 0 (pre-dose), hour 1, 2, 4, 6, 8 and 12 after administration
day 2 - time 0 (pre-dose, 24 hour after the first dose)
day 4 - time 0 (pre-dose, 24 hour after the third dose)
day 8- time 0 (pre-dose, 24 hour after the seventh dose) and at hour 1, 2, 4, 6, 8, 12, 24, 36 and 48 after the eighth and last dose.

Chart 1: mean plasma concentration-time profiles
of genistein and daidzein in healthy volunteers after
repeated administration of 400 mg of Soyselect®

As reported in chart 1, genistein and daidzein show a biphasic profile (already obsevered in the previous study), with a first peak achieved 1-2 hours after administration and a second peak between 4 and 12 hours after the administration. Besides, the rate and extent of absorption of genistein and daidzein did not vary significantly after repeated administration, thus suggesting that accumulation effects are not occurring with the dose and schedule used in the current study.

(1) Report Pharm/01/99 - Indena S.p.A., Internal File.
(2) Report Pharm/01/00 - Indena S.p.A., Internal File.
(3) Report Pharm/02/98 - Indena S.p.A., Internal File.
(4) Gallo D., Cantelmo F., Giacomelli S., Riva A., Morazzoni P., Bombardelli E., Mancuso S., Scambia G., Eurotox’ 99 - XXXVII European Congress of Toxicology, June 27-30, 1999 - Oslo, Norvay.
(5) Report B.T. 01/97, March 28, 1997 - Indena S.p.A., Internal File.
(6) Report B.T. 04/97/CL, April 28, 1997 - Indena S.p.A., Internal File; Report B.T. 04/97/AN, April 28, 1997 - Indena S.p.A., Internal File.; Report B.T. 04/97PK, May 5, 1997 - Indena S.p.A., Internal File.