Significant differences in estradiol bioavailability from two similarly labelled estradiol matrix transdermal systems.
OBJECTIVE
To compare the bioavailabilities of estradiol delivered by two transdermal estradiol matrix systems; Alora and Evorel.


METHODS
A single-center, open-label, randomized, two-period cross-over study in 33 postmenopausal women. The subjects received two successive 84-h applications of either Alora or Evorel (each labelled to deliver 50 micrograms/day 17 beta-estradiol) in a randomized sequence. Serial serum samples, collected over the 84-h period following the application of the second patch, were analyzed for estradiol using a validated radioimmunoassay method.


RESULTS
The fluctuation index produced by Evorel was significantly higher than that produced by Alora (Evorel, 135%; Alora, 76%; p < 0.0005). In addition, the estradiol baseline-corrected area under the curve for Evorel was significantly lower than that for Alora (Alora, 2871.8 pg h/ml; Evorel, 1870.6 pg h/ml; p < 0.0005). Both patches were found to be generally well tolerated.


CONCLUSIONS
Alora delivered a higher, more consistent concentration of estradiol into the systemic circulation over the entire dosing interval than did Everol. Although the full clinical significance of these findings is currently unknown, this study demonstrates that there are significant differences in estradiol delivery from these two products, although they are labelled with the same nominal delivery rate.
Buch
A B
AB
Procter & Gamble Pharmaceuticals, Clinical Pharmacology and Pharmacokinetics, PO Box 8006, Mason, Ohio 45040, USA.
Shen
L Z
LZ
Kelly
S C
SC
Russell
D A
DA
Sahota
R S
RS
Bixler
C A
CA
Moehrke
W
W
Powell
J H
JH
D000279:Administration, Cutaneous; D000368:Aged; D001682:Biological Availability; D018592:Cross-Over Studies; D004958:Estradiol / Q000008:administration & dosage* / Q000009:adverse effects / Q000493:pharmacokinetics*; D005260:Female; D006801:Humans; D007700:Kinetics; D008875:Middle Aged; D017698:Postmenopause
D004958:Estradiol