PREMPHASE 14/14
Clinical safety rating: caution
Comprehensive clinical and safety monograph for PREMPHASE 14/14 (PREMPHASE 14/14).
Conjugated estrogens (CE) bind to estrogen receptors (ERα and ERβ), modulating gene transcription and non-genomic signaling pathways to induce estrogenic effects. Medroxyprogesterone acetate (MPA) is a progestin that binds to progesterone receptors, suppressing endometrial proliferation and counteracting estrogen-induced endometrial hyperplasia. The combination provides hormone replacement therapy with reduced risk of endometrial cancer.
| Metabolism | Conjugated estrogens are primarily metabolized in the liver via cytochrome P450 3A4 (CYP3A4) and other CYP enzymes, with conjugation (glucuronidation and sulfation) to inactive metabolites. Medroxyprogesterone acetate is extensively metabolized in the liver, primarily via hydroxylation and conjugation, with CYP3A4 playing a major role. Both undergo enterohepatic recirculation and are excreted in urine and feces. |
| Excretion | Conjugated estrogens are excreted primarily in urine (≥90%) as glucuronide and sulfate conjugates; medroxyprogesterone acetate is extensively metabolized and excreted in urine (≤60%) and feces (≤30%) as metabolites. |
| Half-life | Conjugated estrogens have a terminal elimination half-life of 12-24 hours for conjugated equine estrogens; medroxyprogesterone acetate has a half-life of 12-17 hours. Steady-state is reached within 5-7 days. |
| Protein binding | Conjugated estrogens: ~50-80% bound to albumin and sex hormone-binding globulin (SHBG); medroxyprogesterone acetate: ~85-90% bound to albumin (not SHBG). |
| Volume of Distribution | Conjugated estrogens: Vd ~1-2 L/kg, distributed widely into tissues including breast, uterine, and adipose tissue; medroxyprogesterone acetate: Vd ~0.5-1 L/kg. |
| Bioavailability | Oral bioavailability of conjugated estrogens is 60-80%; medroxyprogesterone acetate is 100% (oral). Transdermal or vaginal routes for estrogens alone show 10-20% absorption vs oral. |
| Onset of Action | Oral: Onset of estrogenic effects (e.g., relief of vasomotor symptoms) within 2-4 weeks; progestogenic effects on endometrium occur after 10-14 days of continuous dosing. |
| Duration of Action | Extended duration: For vasomotor symptoms, continuous daily dosing required; for endometrial protection, 14 days of progestin per cycle (cyclic regimen). Clinical effects persist for 24-48 hours after last dose. |
One tablet orally once daily, each tablet contains conjugated estrogens 0.625 mg and medroxyprogesterone acetate 5 mg.
| Dosage form | TABLET |
| Renal impairment | No specific dose adjustment recommended; use with caution in patients with renal impairment. |
| Liver impairment | Contraindicated in patients with severe hepatic disease (Child-Pugh class C); use with caution in mild to moderate impairment (Child-Pugh class A or B) with dose reduction as clinically indicated. |
| Pediatric use | Not indicated for use in pediatric patients. |
| Geriatric use | No specific dose adjustment; monitor for adverse effects such as thromboembolic events and malignancy. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for PREMPHASE 14/14 (PREMPHASE 14/14).
| Breastfeeding | Estrogens and progestins are excreted in human milk in small amounts. Milk-to-plasma ratio (M/P) for conjugated estrogens is approximately 0.4-0.6; for MPA, M/P ratio is about 0.3-0.5. Exposed infants may experience jaundice, breast enlargement, or hormonal effects. PREMPHASE may reduce milk production and quality. Breastfeeding is generally not recommended during therapy; if used, monitor infant for adverse effects. |
| Teratogenic Risk | PREMARIN (conjugated estrogens) and medroxyprogesterone acetate (MPA) are contraindicated in pregnancy. Estrogen use during first trimester is associated with urogenital tract abnormalities (e.g., hypospadias) and possible transgenerational effects. Second and third trimester exposure may increase risk of fetal reproductive tract abnormalities (e.g., vaginal adenosis, clear cell adenocarcinoma) from DES-like effects, though risk is lower with current formulations. MPA is a progestin with potential androgenic effects; animal studies show feminization of male fetuses and masculinization of female fetuses at high doses. Overall, use in pregnancy is contraindicated. |
■ FDA Black Box Warning
Estrogen-plus-progestin therapy should not be used for the prevention of cardiovascular disease. The Women's Health Initiative (WHI) study reported increased risks of myocardial infarction, stroke, invasive breast cancer, pulmonary emboli, and deep vein thrombosis in postmenopausal women (50-79 years) treated with daily oral CE 0.625 mg/MPA 2.5 mg. Risks are dose- and duration-dependent.
| Serious Effects |
["Undiagnosed abnormal genital bleeding","Known, suspected, or history of breast cancer","Known or suspected estrogen-dependent neoplasia (e.g., endometrial cancer)","Active or history of deep vein thrombosis, pulmonary embolism, or thrombophlebitis","Active or history of arterial thromboembolic disease (e.g., stroke, MI)","Known protein C, protein S, or antithrombin deficiency (or other thrombophilic disorders)","Known or suspected pregnancy","Liver dysfunction or disease (e.g., active hepatitis, cirrhosis)","Hypersensitivity to conjugated estrogens, medroxyprogesterone acetate, or any ingredients"]
| Precautions | ["Cardiovascular disorders: Increased risk of stroke and DVT; discontinue if thrombosis suspected.","Malignancy: Increased risk of breast cancer (especially with combined therapy), endometrial cancer (estrogen-alone therapy), and ovarian cancer; perform regular breast exams and mammography.","Dementia: Possible increased risk in women ≥65 years; avoid use for prevention.","Gallbladder disease: Increased risk requiring cholecystectomy.","Hypercalcemia: May occur in women with breast cancer and bone metastases.","Visual abnormalities: Discontinue if sudden partial or complete vision loss occurs (consider retinal vascular thrombosis).","Fluid retention: Use with caution in conditions exacerbated by fluid retention (e.g., cardiac/renal dysfunction).","Hypothyroidism: May increase thyroid-binding globulin levels, requiring dose adjustment of thyroid hormone.","Triglyceride elevations: Use with caution in patients with hypertriglyceridemia; monitor levels."] |
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| Fetal Monitoring | Maternal: Blood pressure, liver function, glucose tolerance, thyroid function, serum lipid profile, and endometrial assessment (if uterus intact). Fetal: Not indicated as drug is contraindicated in pregnancy; if inadvertent exposure occurs, monitor for urogenital anomalies and developmental outcomes. |
| Fertility Effects | Estrogen-progestin combinations suppress ovulation and may impair fertility during use. After discontinuation, fertility typically returns, but prolonged use may delay return of ovulatory cycles. Endometrial changes from progestin component can affect implantation. No evidence of permanent fertility impairment. |