Plasma concentrations of progesterone are higher in the uterine artery than in the radial artery after vaginal administration of micronized progesterone in an oil-based solution to postmenopausal women.
OBJECTIVE
To verify the occurrence of preferential distribution of vaginally administered progesterone to the uterus compared with extrapelvic regions in vivo and in humans.


METHODS
Prospective clinical study.


METHODS
University medical school.


METHODS
Twenty postmenopausal women undergoing transabdominal hysterectomy for benign pathologies.


METHODS
Forty-five minutes before surgery, the women received a single vaginal administration of an oil-based micronized progesterone (100 mg) solution currently available on the market for IM use. During the operation, parallel blood samples were drawn from the uterine and radial arteries.


METHODS
Plasma levels of progesterone were measured by RIA.


RESULTS
Mean (+/- SD) plasma levels of progesterone were significantly higher in the uterine artery than in the radial artery (9.75 +/- 3.21 vs. 5.12 +/- 2.06 ng/mL, respectively).


CONCLUSIONS
Vaginal administration allows a preferential distribution of progesterone to the uterus, which confirms the existence of the so-called "first uterine pass effect."
Cicinelli
E
E
Department of Gynecology and Obstetrics, Medical School, University of Bari, Italy.
Cignarelli
M
M
Sabatelli
S
S
Romano
F
F
Schonauer
L M
LM
Padovano
R
R
Einer-Jensen
N
N
D000282:Administration, Intravaginal; D001158:Arteries; D005260:Female; D006801:Humans; D008875:Middle Aged; D017698:Postmenopause; D011374:Progesterone / Q000008:administration & dosage* / Q000097:blood*; D011446:Prospective Studies; D017534:Radial Artery; D012996:Solutions; D014599:Uterus / Q000098:blood supply*
D012996:Solutions; D011374:Progesterone