From the FDA Drug Label
The clinical relevance of the in vitro findings is unknown Coadministration of conjugated estrogens and progesterone capsules to 29 postmenopausal women over a 12-day period resulted in an increase in total estrone concentrations (Cmax 3.68 ng/mL to 4.93 ng/mL) and total equilin concentrations (Cmax 2.27 ng/mL to 3.22 ng/mL) and a decrease in circulating 17β estradiol concentrations (Cmax 0.037 ng/mL to 0. 030 ng/mL). TABLE 2. Mean (± S.D.) Pharmacokinetic Parameters for Estradiol, Estrone, and Equilin Following Coadministration of Conjugated Estrogens 0. 625 mg and Progesterone Capsules 200 mg for 12 Days to Postmenopausal Women Conjugated EstrogensConjugated Estrogens plus Progesterone Capsules DrugCmax (ng/mL)Tmax (hr)AUC(0-24h) (ng × h/mL)Cmax (ng/mL)Tmax (hr)AUC(0-24h) (ng × h/mL) Estradiol 0.037 ± 0.04812.7 ± 9.10.676 ± 0.7370.030 ± 0.03217.32 ± 1.210.561 ± 0.572 Estrone Total a 3.68 ± 1.5510.6 ± 6.861.3 ± 26.364.93 ± 2.077.5 ± 3.885.9 ± 41. 2 Equilin Total a2.27 ± 0.956.0 ± 4.028.8 ± 13.03.22 ± 1.135.3 ± 2.638.1 ± 20.2
The normal progesterone estrogen ratio is not explicitly stated in the provided drug label. However, the label does provide information on the pharmacokinetic parameters of progesterone and estrogen when coadministered.
- The label reports an increase in total estrone concentrations and total equilin concentrations, and a decrease in circulating 17β estradiol concentrations when conjugated estrogens and progesterone capsules are coadministered.
- The exact ratio of progesterone to estrogen is not provided, and therefore, no conclusion can be drawn regarding the normal progesterone estrogen ratio 1.
From the Research
The normal progesterone to estrogen ratio varies throughout a woman's menstrual cycle, with no single "ideal" ratio, as these hormones naturally fluctuate in relation to each other throughout the cycle. During the follicular phase, estrogen is dominant with levels ranging from 20-400 pg/mL, while progesterone remains low at about 0.1-1.5 ng/mL 2. At ovulation, estrogen peaks at 100-400 pg/mL. In the luteal phase, progesterone becomes dominant, rising to 2-25 ng/mL, while estrogen levels reach a second, smaller peak of 100-300 pg/mL. This shifting ratio is essential for normal reproductive function, as estrogen builds the uterine lining while progesterone prepares it for potential implantation. Some key points to consider include:
- Hormone balance rather than a specific ratio is what matters for reproductive and overall health 3.
- Significant deviations from these patterns may indicate conditions like estrogen dominance, anovulation, or luteal phase defects, which might require medical evaluation 4.
- The use of progesterone and estrogen in hormone replacement therapy (HRT) is well established, with progesterone acting to counteract the proliferative effects of estradiol on the endometrium 3.
- Recent data suggest that micronized progesterone may be safer for the breast, but less efficient than synthetic progestin on the endometrium 3. Overall, the balance between progesterone and estrogen is crucial for maintaining normal reproductive function and overall health in women, and any significant deviations from normal patterns should be evaluated and addressed by a healthcare professional.