(conjugated estrogens and medroxyprogesterone acetate)
12 CLINICAL PHARMACOLOGY
12 CLINICAL PHARMACOLOGY
12.1 Mechanism of Action
Endogenous estrogens are largely responsible for the development and maintenance of the female reproductive system and secondary sexual characteristics. Although circulating estrogens exist in a dynamic equilibrium of metabolic interconversions, estradiol is the principal intracellular human estrogen and is substantially more potent than its metabolites, estrone and estriol, at the receptor level.
The primary source of estrogen in normally cycling adult women is the ovarian follicle, which secretes 70 to 500 mcg of estradiol daily, depending on the phase of the menstrual cycle. After menopause, most endogenous estrogen is produced by conversion of androstenedione, which is secreted by the adrenal cortex, to estrone in the peripheral tissues. Thus, estrone and the sulfate-conjugated form, estrone sulfate, are the most abundant circulating estrogens in postmenopausal women.
Estrogens act through binding to nuclear receptors in estrogen-responsive tissues. To date, two estrogen receptors have been identified. These vary in proportion from tissue to tissue.
Circulating estrogens modulate the pituitary secretion of the gonadotropins, luteinizing hormone (LH) and FSH, through a negative feedback mechanism. Estrogens act to reduce the elevated levels of these gonadotropins seen in postmenopausal women.
Parenterally administered medroxyprogesterone acetate (MPA) inhibits gonadotropin production, which in turn prevents follicular maturation and ovulation; although available data indicate that this does not occur when the usually recommended oral dosage is given as single daily doses. MPA may achieve its beneficial effect on the endometrium in part by decreasing nuclear estrogen receptors and suppression of epithelial DNA synthesis in endometrial tissue. Androgenic and anabolic effects of MPA have been noted, but the drug is apparently devoid of significant estrogenic activity.
12.2 Pharmacodynamics
Currently, there are no pharmacodynamic data known for PREMPRO or PREMPHASE tablets.
12.3 Pharmacokinetics
Absorption
PREMPRO and PREMPHASE contain a formulation of medroxyprogesterone acetate (MPA) that is immediately released and CE that are slowly released over several hours. Conjugated estrogens are water-soluble and are well-absorbed from the gastrointestinal tract after release from the drug formulation. MPA is well absorbed from the gastrointestinal tract. Table 3 and Table 4 summarize the mean pharmacokinetic parameters for select unconjugated and conjugated estrogens and medroxyprogesterone acetate following administration of PREMPRO to healthy, postmenopausal women.
| BA* = Baseline adjusted Cmax = peak plasma concentration tmax = time peak concentration occurs t1/2 = apparent terminal-phase disposition half-life (0.693/λz) AUC = total area under the concentration-time curve | ||||||||
DRUG | 2 × 0.625 mg CE/2.5 mg MPA | 2 × 0.625 mg CE/5 mg MPA | ||||||
PK Parameter | Cmax | tmax | t1/2 | AUC | Cmax | tmax | t1/2 | AUC |
Unconjugated Estrogens | ||||||||
Estrone | 175 | 7.6 | 31.6 | 5358 | 124 | 10 | 62.2 | 6303 |
BA* -Estrone | 159 | 7.6 | 16.9 | 3313 | 104 | 10 | 26.0 | 3136 |
Equilin | 71 | 5.8 | 9.9 | 951 | 54 | 8.9 | 15.5 | 1179 |
PK Parameter | Cmax | tmax | t1/2 | AUC | Cmax | tmax | t1/2 | AUC |
Conjugated Estrogens | ||||||||
Total Estrone | 6.6 | 6.1 | 20.7 | 116 | 6.3 | 9.1 | 23.6 | 151 |
BA* -Total Estrone | 6.4 | 6.1 | 15.4 | 100 | 6.2 | 9.1 | 20.6 | 139 |
Total Equilin | 5.1 | 4.6 | 11.4 | 50 | 4.2 | 7.0 | 17.2 | 72 |
PK Parameter | Cmax | tmax | t1/2 | AUC | Cmax | tmax | t1/2 | AUC |
Medroxyprogesterone Acetate | ||||||||
MPA | 1.5 | 2.8 | 37.6 | 37 | 4.8 | 2.4 | 46.3 | 102 |
| BA* = Baseline adjusted Cmax = peak plasma concentration tmax = time peak concentration occurs t1/2 = apparent terminal-phase disposition half-life (0.693/λz) AUC = total area under the concentration-time curve | ||||
DRUG | 4 × 0.45 mg CE/1.5 mg MPA Combination | |||
PK Parameter | Cmax | tmax | t1/2 | AUC |
Unconjugated Estrogens | ||||
Estrone | 149 | 8.9 | 37.5 | 6641 |
BA* -Estrone | 130 | 8.9 | 21.2 | 3799 |
Equilin | 83 | 8.3 | 15.9 | 1889 |
PK Parameter | Cmax | tmax | t1/2 | AUC |
Conjugated Estrogens | ||||
Total Estrone | 5.4 | 7.9 | 22.4 | 119 |
BA* -Total Estrone | 5.2 | 7.9 | 15.1 | 100 |
Total Equilin | 4.3 | 6.5 | 11.6 | 74 |
PK Parameter | Cmax | tmax | t1/2 | AUC |
Medroxyprogesterone Acetate | ||||
MPA | 0.7 | 2.0 | 26.2 | 5.0 |
Food-Effect: Single dose studies in healthy, postmenopausal women were conducted to investigate any potential drug interaction when PREMPRO or PREMPHASE is administered with a high-fat breakfast. Administration with food decreased the Cmax of total estrone by 18 to 34% and increased total equilin Cmax by 38% compared to the fasting state, with no other effect on the rate or extent of absorption of other conjugated or unconjugated estrogens. Administration with food approximately doubles MPA Cmax and increases MPA AUC by approximately 20 to 30%.
Dose Proportionality: The Cmax and AUC values for MPA observed in two separate pharmacokinetic studies conducted with 2 PREMPRO 0.625 mg/2.5 mg or 2 PREMPRO or PREMPHASE 0.625 mg/5 mg tablets exhibited nonlinear dose proportionality; doubling the MPA dose from 2 × 2.5 to 2 × 5 mg increased the mean Cmax and AUC by 3.2- and 2.8-fold, respectively.
The dose proportionality of estrogens and medroxyprogesterone acetate was assessed by combining pharmacokinetic data across another two studies totaling 61 healthy, postmenopausal women. Single CE doses of 2 × 0.3 mg, 2 × 0.45 mg, or 2 × 0.625 mg were administered either alone or in combination with medroxyprogesterone acetate doses of 2 × 1.5 mg or 2 × 2.5 mg. Most of the estrogen components demonstrated dose proportionality; however, several estrogen components did not. Medroxyprogesterone acetate pharmacokinetic parameters increased in a dose-proportional manner.
Distribution
The distribution of exogenous estrogens is similar to that of endogenous estrogens. Estrogens are widely distributed in the body and are generally found in higher concentrations in the sex hormone target organs. Estrogens circulate in the blood largely bound to SHBG and albumin. MPA is approximately 90% bound to plasma proteins, but does not bind to SHBG.
Metabolism
Exogenous estrogens are metabolized in the same manner as endogenous estrogens. Circulating estrogens exist in a dynamic equilibrium of metabolic interconversions. These transformations take place mainly in the liver. Estradiol is converted reversibly to estrone, and both can be converted to estriol, which is a major urinary metabolite. Estrogens also undergo enterohepatic recirculation via sulfate and glucuronide conjugation in the liver, biliary secretion of conjugates into the intestine, and hydrolysis in the intestine followed by reabsorption. In postmenopausal women, a significant proportion of the circulating estrogens exist as sulfate conjugates, especially estrone sulfate, which serves as a circulating reservoir for the formation of more active estrogens. Metabolism and elimination of MPA occur primarily in the liver via hydroxylation, with subsequent conjugation and elimination in the urine.
PATIENT INFORMATION
PATIENT INFORMATION
PREMPRO®
(Conjugated Estrogens/Medroxyprogesterone Acetate Tablets)
PREMPHASE®
(Conjugated Estrogens plus Medroxyprogesterone Acetate Tablets)
Read this PATIENT INFORMATION before you start taking PREMPRO or PREMPHASE and read what you get each time you refill your PREMPRO or PREMPHASE prescription. There may be new information. This information does not take the place of talking to your healthcare provider about your medical condition or your treatment.
What is the most important information I should know about PREMPRO and PREMPHASE (combinations of estrogens and a progestin)?
|
What is PREMPRO or PREMPHASE?
PREMPRO or PREMPHASE are medicines that contain two kinds of hormones, estrogens and a progestin.
What is PREMPRO or PREMPHASE used for?
PREMPRO or PREMPHASE is used after menopause to:
- •
- Reduce moderate to severe hot flushes
Estrogens are hormones made by a woman's ovaries. The ovaries normally stop making estrogens when a woman is between 45 and 55 years old. This drop in body estrogen levels causes the "change of life" or menopause (the end of monthly menstrual periods). Sometimes, both ovaries are removed during an operation before natural menopause takes place. The sudden drop in estrogen levels causes "surgical menopause."
When the estrogen levels begin dropping, some women get very uncomfortable symptoms, such as feelings of warmth in the face, neck, and chest, or sudden strong feelings of heat and sweating ("hot flushes"). In some women the symptoms are mild, and they will not need to take estrogens. In other women, symptoms can be more severe. - •
- Treat menopausal changes in and around the vagina
You and your healthcare provider should talk regularly about whether you still need treatment with PREMPRO or PREMPHASE to control these problems. If you use PREMPRO or PREMPHASE only to treat your menopausal changes in and around your vagina, talk with your healthcare provider about whether a topical vaginal product would be better for you. - •
- Help reduce your chances of getting osteoporosis (thin weak bones)
Osteoporosis from menopause is a thinning of the bones that makes them weaker and easier to break. If you use PREMPRO or PREMPHASE only to prevent osteoporosis due to menopause, talk with your healthcare provider about whether a different treatment or medicine without estrogens might be better for you. Weight-bearing exercise, like walking or running, and taking calcium (1500 mg per day of elemental calcium) and vitamin D (400–800 IU per day) supplements may also lower your chances of getting postmenopausal osteoporosis. It is important to talk about exercise and supplements with your healthcare provider before starting them.
You and your healthcare provider should talk regularly about whether you still need treatment with PREMPRO or PREMPHASE.
Who should not take PREMPRO or PREMPHASE?
Do not take PREMPRO or PREMPHASE if you have had your uterus (womb) removed (hysterectomy).
PREMPRO and PREMPHASE contain a progestin to decrease the chance of getting cancer of the uterus. If you do not have a uterus, you do not need a progestin and you should not take PREMPRO or PREMPHASE.
Do not take PREMPRO or PREMPHASE if you:
- •
- Have unusual vaginal bleeding
- •
- Currently have or have had certain cancers
Estrogens may increase the chance of getting certain types of cancers, including cancer of the breast or uterus. If you have or have had cancer, talk with your healthcare provider about whether you should use PREMPRO or PREMPHASE. - •
- Had a stroke or heart attack
- •
- Currently have or have had blood clots
- •
- Currently have or have had liver problems
- •
- Have been diagnosed with a bleeding disorder
- •
- Are allergic to PREMPRO or PREMPHASE or any of their ingredients
See the list of ingredients in PREMPRO and PREMPHASE at the end of this leaflet.
Tell your healthcare provider
- •
- If you have any unusual vaginal bleeding
Vaginal bleeding after menopause may be a warning sign of cancer of the uterus (womb). Your healthcare provider should check any unusual vaginal bleeding to find out the cause. - •
- About all of your medical problems
Your healthcare provider may need to check you more carefully if you have certain conditions, such as asthma (wheezing), epilepsy (seizures), diabetes, migraine, endometriosis, lupus, problems with your heart, liver, thyroid, kidneys, or have high calcium levels in your blood. - •
- About all the medicines you take
This includes prescription and nonprescription medicines, vitamins, and herbal supplements. Some medicines may affect how PREMPRO or PREMPHASE works. PREMPRO or PREMPHASE may also affect how your other medicines work. - •
- If you are going to have surgery or will be on bedrest
You may need to stop taking PREMPRO or PREMPHASE. - •
- If you are pregnant or think you may be pregnant
PREMPRO and PREMPHASE are not for pregnant women.
- •
- If you are breastfeeding
The hormones in PREMPRO and PREMPHASE can pass into your breast milk.
How should I take PREMPRO or PREMPHASE?
- •
- Take one PREMPRO or PREMPHASE tablet at the same time each day
- •
- If you miss a dose, take it as soon as possible
If it is almost time for your next dose, skip the missed dose and go back to your normal schedule. Do not take 2 doses at the same time. - •
- Estrogens should be used at the lowest dose possible for your treatment only as long as needed
You and your healthcare provider should talk regularly (for example, every 3 to 6 months) about the dose you are taking and whether you still need treatment with PREMPRO or PREMPHASE.
What are the possible side effects of PREMPRO or PREMPHASE?
Side effects are grouped by how serious they are and how often they happen when you are treated.
Serious, but less common side effects include:
- •
- Heart attack
- •
- Stroke
- •
- Blood clots
- •
- Breast cancer
- •
- Cancer of the lining of the uterus (womb)
- •
- Cancer of the ovary
- •
- Dementia
- •
- High or low blood calcium
- •
- Gallbladder disease
- •
- Visual abnormalities
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- High blood pressure
- •
- High levels of fat (triglycerides) in your blood
- •
- Liver problems
- •
- Changes in your thyroid hormone levels
- •
- Fluid retention
- •
- Cancer changes of endometriosis
- •
- Enlargement of benign tumors of the uterus ("fibroids")
- •
- Severe allergic reactions
- •
- Changes in certain laboratory test results, such as high blood sugar
Call your healthcare provider right away if you get any of the following warning signs or any other unusual symptoms that concern you:
- •
- New breast lumps
- •
- Unusual vaginal bleeding
- •
- Changes in vision or speech
- •
- Sudden new severe headaches
- •
- Severe pains in your chest or legs with or without shortness of breath, weakness and fatigue
- •
- Swelling of the face, lips, and tongue with or without red itchy bumps
Common side effects of PREMPRO or PREMPHASE include:
- •
- Headache
- •
- Breast pain
- •
- Irregular vaginal bleeding or spotting
- •
- Stomach or abdominal cramps, bloating
- •
- Nausea and vomiting
- •
- Hair loss
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- Fluid retention
- •
- Vaginal yeast infection
These are not all the possible side effects of PREMPRO or PREMPHASE. For more information, ask your healthcare provider or pharmacist for advice about side effects. You may report side effects to Pfizer Inc. at 1-800-438-1985 or to FDA at 1-800-FDA-1088.
What can I do to lower my chances of getting a serious side effect with PREMPRO or PREMPHASE?
- •
- Talk with your healthcare provider regularly about whether you should continue taking PREMPRO or PREMPHASE
- •
- See your healthcare provider right away if you get vaginal bleeding while taking PREMPRO or PREMPHASE
- •
- Have a pelvic exam, breast exam and mammogram (breast X-ray) every year unless your healthcare provider tells you something else
If members of your family have had breast cancer or if you have ever had breast lumps or an abnormal mammogram, you may need to have breast exams more often. - •
- If you have high blood pressure, high cholesterol (fat in the blood), diabetes, are overweight, or if you use tobacco, you may have higher chances for getting heart disease
Ask your healthcare provider for ways to lower your chances of getting heart disease.
General Information about the safe and effective use of PREMPRO and PREMPHASE
Medicines are sometimes prescribed for conditions that are not mentioned in patient information leaflets. Do not take PREMPRO or PREMPHASE for conditions for which it was not prescribed. Do not give PREMPRO or PREMPHASE to other people, even if they have the same symptoms you have. It may harm them.
Keep PREMPRO and PREMPHASE out of the reach of children.
This leaflet provides a summary of the most important information about PREMPRO and PREMPHASE. If you would like more information, talk with your healthcare provider or pharmacist. You can ask for information about PREMPRO and PREMPHASE that is written for health professionals.
What are the ingredients in PREMPRO and PREMPHASE?
PREMPRO contains the same conjugated estrogens found in Premarin, which are a mixture of sodium estrone sulfate and sodium equilin sulfate and other components, including sodium sulfate conjugates, 17α-dihydroequilin, 17α-estradiol and 17β-dihydroequilin. PREMPRO also contains either 1.5, 2.5, or 5 mg of medroxyprogesterone acetate.
PREMPRO 0.3 mg/1.5 mg and 0.45 mg/1.5 mg tablets also contain calcium phosphate tribasic, microcrystalline cellulose, lactose monohydrate, carnauba wax, hypromellose, magnesium stearate, polyethylene glycol, sucrose, hydroxypropyl cellulose, Eudragit NE 30D, titanium dioxide, yellow iron oxide, propylene glycol and black iron oxide.
PREMPRO 0.625 mg/2.5 mg tablets also contain calcium phosphate tribasic, microcrystalline cellulose, carnauba wax, lactose monohydrate, hypromellose, magnesium stearate, polyethylene glycol, sucrose, hydroxypropyl cellulose, Eudragit NE 30D, propylene glycol, titanium dioxide, red iron oxide, yellow iron oxide, and black iron oxide.
PREMPRO 0.625 mg/5 mg tablets also contain calcium phosphate tribasic, carnauba wax, Eudragit NE 30D, hydroxypropyl cellulose, hypromellose, lactose monohydrate, magnesium stearate, microcrystalline cellulose, polyethylene glycol, sucrose, titanium dioxide, triethyl citrate, FD&C Blue No. 2, black iron oxide, and propylene glycol.
PREMPHASE is two separate tablets. One tablet (maroon color) is 0.625 mg of Premarin, which is a mixture of sodium estrone sulfate and sodium equilin sulfate and other components, including sodium sulfate conjugates, 17 α-dihydroequilin, 17 α-estradiol and 17 β-dihydroequilin. The maroon tablet also contains calcium phosphate tribasic, carnauba wax, hydroxypropyl cellulose, microcrystalline cellulose, powdered cellulose, hypromellose, lactose monohydrate, magnesium stearate, polyethylene glycol, sucrose, titanium dioxide, propylene glycol, FD&C Blue No. 2, FD&C Red No. 40. The second tablet (light-blue color) contains 0.625 mg of the same ingredients as the maroon color tablet plus 5 mg of medroxyprogesterone acetate. The light-blue tablet also contains calcium phosphate tribasic, carnauba wax, Eudragit NE 30D, hydroxypropyl cellulose, hypromellose, lactose monohydrate, magnesium stearate, microcrystalline cellulose, polyethylene glycol, sucrose, titanium dioxide, triethyl citrate, FD&C Blue No. 2, black iron oxide, and propylene glycol.
PREMPRO therapy consists of a single tablet to be taken once daily.
PREMPRO 0.3 mg/1.5 mg
Blister Card - Each carton includes 1 blister card containing 28 oval, cream tablets. Each tablet contains 0.3 mg of the conjugated estrogens found in Premarin tablets and 1.5 mg of medroxyprogesterone acetate for oral administration.
PREMPRO 0.45 mg/1.5 mg
Blister Card - Each carton includes 1 blister card containing 28 oval, gold tablets. Each tablet contains 0.45 mg of the conjugated estrogens found in Premarin tablets and 1.5 mg of medroxyprogesterone acetate for oral administration.
PREMPRO 0.625 mg/2.5 mg
Blister Card - Each carton includes 1 blister card containing 28 oval, peach tablets. Each tablet contains 0.625 mg of the conjugated estrogens found in Premarin tablets and 2.5 mg of medroxyprogesterone acetate for oral administration.
PREMPRO 0.625 mg/5 mg
Blister Card - Each carton includes 1 blister card containing 28 oval, light-blue tablets. Each tablet contains 0.625 mg of the conjugated estrogens found in Premarin tablets and 5 mg of medroxyprogesterone acetate for oral administration.
PREMPHASE therapy consists of two separate tablets; one maroon Premarin tablet taken daily on days 1 through 14 and one light-blue tablet taken on days 15 through 28.
Each carton includes 1 blister pack containing 28 tablets. One blister pack contains 14 oval, maroon Premarin tablets containing 0.625 mg of conjugated estrogens and 14 oval, light-blue tablets that contain 0.625 mg of the conjugated estrogens found in Premarin tablets and 5 mg of medroxyprogesterone acetate for oral administration.
The appearance of PREMPRO tablets is a trademark of Pfizer Inc.
The appearance of PREMARIN tablets is a trademark of Pfizer Inc. The appearance of the conjugated estrogens/medroxyprogesterone acetate combination tablets is a trademark.
Store at 20° to 25°C (68° to 77°F); excursions permitted to 15° to 30°C (59° to 86°F) [see USP Controlled Room Temperature].
This product's labeling may have been updated. For the most recent prescribing information, please visit www.pfizer.com. |
LAB-0504-11.0
Revised 04/2025
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