Steady-state pharmacokinetics of conjugated equine estrogens in healthy, postmenopausal women.
OBJECTIVE
To determine the steady-state exposure of conjugated and unconjugated estrogen components following oral administration of conjugated equine estrogens (2 0.625-mg tablets).


METHODS
A prospective, open-label, single-treatment study conducted at 1 clinical site with 12 healthy, postmenopausal women. Each subject received 7 daily doses of 2 conjugated equine estrogen (0.625-mg) tablets, and blood samples were taken on the last day of dosing for pharmacokinetic analysis of estrogen components.


RESULTS
The major estrogen components after estrogen dosing (as determined by steady-state plasma concentration-time curves) were estrone (100 ng x h/mL), equilin (43.1 ng x h/mL) and delta8,9-dehydroestrone (13.6 ng x h/mL). Several 17beta-reduced forms of estrogen also had consistent plasma concentrations during a steady-state dosing interval. Mean t(max) values ranged from 6.2 to 9.0 hours after dosing, and the 24-hour profiles of the various plasma estrogen concentrations at steady state showed limited fluctuations.


CONCLUSIONS
Oral dosing of conjugated equine estrogen at steady state resulted in consistent concentrations of estrogen components during a dosing interval.
Mayer
Philip
P
Wyeth Pharmaceuticals, Collegeville, Pennsylvania, USA. mayerp@wyeth.com
Tse
Susanna
S
Sendi
Mary
M
Bourg
Dale
D
Morrison
Dennis
D
D000284:Administration, Oral; D000328:Adult; D000368:Aged; D004967:Estrogens / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D004966:Estrogens, Conjugated (USP) / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D005260:Female; D006801:Humans; D008875:Middle Aged; D017698:Postmenopause / Q000187:drug effects*
D004967:Estrogens; D004966:Estrogens, Conjugated (USP)