CLINICAL PHARMACOLOGY
Progesterone is a naturally occurring steroid that is secreted by the ovary, placenta, and adrenal gland.
In the presence of adequate estrogen, progesterone transforms a proliferative endometrium into a
secretory endometrium. Progesterone is essential for the development of decidual tissue, and the effect
of progesterone on the differentiation of glandular epithelia and stroma has been extensively studied.
Progesterone is necessary to increase endometrial receptivity for implantation of an embryo. Once an
embryo is implanted, progesterone acts to maintain the pregnancy. Normal or near-normal endometrial
responses to oral estradiol and intramuscular progesterone have been noted in functionally agonadal
women through the sixth decade of life. Progesterone administration decreases the circulatory levels
of gonadotropins.
Pharmacokinetics
Absorption
Due to the sustained release properties of Crinone, progesterone absorption is prolonged with an
absorption half-life of approximately 25 to 50 hours, and an elimination half-life of 5 to 20 minutes.
Therefore, the pharmacokinetics of Crinone are rate-limited by absorption rather than by elimination.
The bioavailability of progesterone in Crinone was determined relative to progesterone administered
intramuscularly. In a single dose crossover study, 20 healthy, estrogenized postmenopausal women
received 45 mg or 90 mg progesterone vaginally in Crinone 4% or Crinone 8%, or 45 mg or 90 mg
progesterone intramuscularly. The pharmacokinetic parameters (mean ± standard deviation) are shown in
Table 1.
TABLE 1 Single Dose Relative Bioavailability
|
Crinone 4% |
45 mg Intramuscular
Progesterone |
Crinone 8% |
90 mg Intramuscular
Progesterone |
C,max(ng/mL) |
13.15 ± 6.49 |
39.06 ± 13.68 |
14.87 ± 6.32 |
53.76 ± 14.9 |
Cavg 0-24 (ng/mL) |
6.94 ± 4.24 |
22.41 ± 4.92 |
6.98 ± 3.21 |
28.98 ± 8.75 |
AUC0-96 (ng·hr/mL) |
288.63 ±
273.72 |
806.26 ± 102.75 |
296.78 ±
129.90 |
1378.91 ± 176.39 |
Tmax (hr) |
5.6 ± 1.84 |
8.2 ± 6.43 |
6.8 ± 3.3 |
9.2 ± 2.7 |
t 1/2(hr) |
55.13 ±
28.04 |
28.05 ± 16.87 |
34.8 ± 11.3 |
19.6 ± 6.0 |
F (%) |
27.6 |
19.8 |
Cmax - maximum progesterone serum concentration
Cavg 0-24 - average progesterone serum concentration over 24 hours
AUC 0-96 - area under the drug concentration versus time curve from 0-96 hours post dose
Tmax - time to maximum progesterone concentration
t1/2 - elimination half-life
F - relative bioavailability |
The multiple dose pharmacokinetics of Crinone 4% and Crinone 8% administered every other day and
Crinone 8% administered daily or twice daily for 12 days were studied in 10 healthy, estrogenized
postmenopausal women in two separate studies. Steady state was achieved within the first 24 hours after
initiation of treatment. The pharmacokinetic parameters (mean ± standard deviation) after the last
administration of Crinone 4% or 8% derived from these studies are shown in Table 2.
TABLE 2 Multiple Dose Pharmacokinetics
|
Assisted Reproductive
Technology |
Secondary Amenorrhea |
Daily Dosing
8% |
Twice Daily Dosing
8% |
Every Other Day
Dosing 4% |
Every Other Day
Dosing 8% |
C,max(ng/mL) |
15.97± 5.05 |
14.57 ± 4.49 |
13.21± 9.46 |
13.67 ± 3.58 |
Cavg 0-24 (ng/mL) |
8.99 ± 3.53 |
11.6 ± 3.47 |
4.05 ± 2.85 |
6.75 ± 2.83 |
Tmax (hr) |
5.40 ± 0.97 |
3.55 ± 2.48 |
6.67 ± 3.16 |
7.00 ± 2.88 |
AUC0-96 (ng·hr/mL) |
391.98
±153.28 |
138.72 ± 41.58 |
242.15 ± 167.88 |
438.36 ± 223.36 |
t 1/2(hr) |
45.00 ± 34.70 |
25.91 ± 6.15 |
49.87 ± 31.20 |
39.08 ± 12.88 |
Distribution
Progesterone is extensively bound to serum proteins (~ 96-99%), primarily to serum albumin and
corticosteroid binding globulin.
Metabolism
The major urinary metabolite of oral progesterone is 5β-pregnan-3α, 20α-diol glucuronide which is
present in plasma in the conjugated form only. Plasma metabolites also include 5β-pregnan-3α-ol-20-one
(5β-pregnanolone) and 5α-pregnan-3α-ol-20-one (5α-pregnanolone).
Excretion
Progesterone undergoes both biliary and renal elimination. Following an injection of labeled
progesterone, 50-60% of the excretion of progesterone metabolites occurs via the kidney;
approximately 10% occurs via the bile and feces, the second major excretory pathway. Overall
recovery of labeled material accounts for 70% of an administered dose, with the remainder of the dose
not characterized with respect to elimination. Only a small portion of unchanged progesterone is
excreted in the bile.
Clinical Studies
Assisted Reproductive Technology
In a single-center, open-label study (COL1620-007US), 99 women (aged 28-47 years) with either
partial (n = 84) or premature ovarian failure (n = 15) who were candidates to receive a donor oocyte
transfer as an Assisted Reproductive Technology ("ART") procedure were randomized to receive
either Crinone 8% twice daily (n = 68) or intramuscular progesterone 100 mg daily (n = 31). The study
was divided into three phases (Pilot, Donor Egg and Treatment). The first phase of the study consisted
of a test Pilot Cycle to ensure that the administration of transdermal estradiol and progesterone would
adequately prime the endometrium to receive the donor egg. The second phase was the Donor Egg
Cycle during which a fertilized oocyte was implanted. Crinone 8% was administered beginning the
evening of Day 14 of the Pilot and Donor Egg cycles. Subjects with partial ovarian function also
underwent a Pre-Pilot Cycle and a Pre-Donor Egg Cycle during which time they were administered
only leuprolide acetate to suppress remaining ovarian function. The Pre-Pilot Cycle, Pilot Cycle, Pre-
Donor Egg Cycle, and Donor Egg Cycle each lasted approximately 34 days. The third phase of the
study consisted of a 10-week treatment period to maintain a pregnancy until placental autonomy was
achieved.
Sixty-one women received Crinone 8% as part of the Pilot Cycle to determine their endometrial
response. Of the 55 evaluable endometrial biopsies in the Crinone 8% group performed on Day 25 to
27, all were histologically "in-phase", consistent with luteal phase biopsy specimens of menstruating
women at comparable time intervals. Fifty-four women who received Crinone 8% and had a
histologically "in-phase" biopsy received a donor oocyte transfer. Among these 54 Crinone-treated
women, clinical pregnancies (assessed about week 10 after transfer by clinical examination, ultrasound
and/or ß-hCG levels) occurred in 26 women (48%). Seventeen women (31%) delivered a total of 25
newborns, seven women (13%) had spontaneous abortions and two women (4%) had elective abortions.
In a second study (COL1620-F01), Crinone 8% was used in luteal phase support of women with tubal or
idiopathic infertility due to endometriosis and normal ovulatory cycles, undergoing in vitro fertilization
("IVF") procedures. All women received a GnRH analog to suppress endogenous progesterone, human
menopausal gonadotropins, and human chorionic gonadotropin. In this multi-center, open-label study,
139 women (aged 22-38 years) received Crinone 8% once daily beginning within 24 hours of embryo
transfer and continuing through Day 30 post-transfer. Clinical pregnancies assessed at Day 90 posttransfer
were seen in 36 (26%) of women. Thirty-two women (23%) delivered newborns and four
women (3%) had spontaneous abortions. (See PRECAUTIONS, Pregnancy)
Secondary Amenorrhea
In three parallel, open-label studies (COL1620-004US, COL1620-005US, COL1620-009US), 127
women (aged 18-44) with hypothalamic amenorrhea or premature ovarian failure were randomized to
receive either Crinone 4% (n = 62) or Crinone 8% (n = 65). All women were treated with either
conjugated estrogens 0.625 mg daily (n = 100) or transdermal estradiol (delivering 50 mcg/day) twice
weekly (n = 27).
Estrogen therapy was continuous for the entire three 28-day cycle studies. At Day 15 of the second
cycle (six weeks after initiating estrogen replacement), women who demonstrated adequate response to
estrogen therapy (by ultrasound) and who continued to be amenorrheic received Crinone every other
day for six doses (Day 15 through Day 25 of the cycle).
In cycle 2, Crinone 4% induced bleeding in 79% of women and Crinone 8% induced bleeding in 77% of
women. In the third cycle, estrogen was continued and Crinone was administered every other day
beginning on Day 15 for six doses. On Day 24 an endometrial biopsy was performed. In 53 women who
received Crinone 4%, biopsy results were as follows: 7% proliferative, 40% late secretory, 19% mid
secretory, 13% early secretory, 7% atrophic, 6% menstrual endometrium, 6% inactive endometrium and
2% negative endometrium. In 54 women who received Crinone 8%, biopsy results were as follows:
44% late secretory, 19% mid secretory, 11% early secretory, 19% atrophic, 5% menstrual endometrium
and 2% "oral contraceptive like" endometrium.