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Drugs reference index «Conjugated estrogens»

Conjugated estrogens

Brand names: Prempro, Premphase, Cenestin, Premarin

Why is Conjugated estrogens prescribed?

Premarin is an estrogen replacement drug. The tablets are used to reduce moderate to severe symptoms of menopause, including feelings of warmth in the face, neck, and chest, and the sudden intense episodes of heat and sweating known as "hot flashes." Cenestin tablets, containing a synthetic form of conjugated estrogens, may also be prescribed for these symptoms.

In addition to the symptoms of menopause, Premarin tablets are prescribed for teenagers who fail to mature at the usual rate, and to relieve the symptoms of certain types of cancer, including some forms of breast and prostate cancer.

In addition, either the tablets or Premarin vaginal cream can be used for other conditions caused by lack of estrogen, such as dry, itchy external genitals and vaginal irritation.

Along with diet, calcium supplements, and exercise, Premarin tablets are also prescribed to prevent postmenopausal osteoporosis, a condition in which the bones become brittle and easily broken. Before taking Premarin solely for this purpose, you should carefully consider using alternative, nonestrogen therapies.

The addition of progesterone to estrogen-replacement therapy has been shown to reduce the risk of uterine cancer. Prempro combines estrogen and progesterone in a single tablet taken once daily. Premphase is a 28-day supply of tablets. The first 14 contain only estrogen. The second 14 supply both estrogen and progesterone. Both Prempro and Premphase are prescribed to reduce the symptoms of menopause, including vaginal problems, and to prevent osteoporosis.

Most important fact about Conjugated estrogens

Because estrogens have been linked with an increased risk of uterine and endometrial cancer (cancer in the lining of the uterus), it is essential to have regular checkups and to report any unusual vaginal bleeding to your doctor immediately.

Premarin and other estrogen drugs, with or without progesterone, should not be used to prevent heart disease. Recent studies have confirmed an increased rate of heart attack, stroke, and dangerous blood clots among women taking estrogen or estrogen combinations for 5 years. Blood clots can lead to phlebitis, stroke, heart attack, a loss of blood supply to the lungs, a blockage in the blood vessels serving the eye, and other serious disorders.

How should you take Conjugated estrogens?

Take Premarin exactly as prescribed. Do not share it with anyone else.

If you are taking calcium supplements as a part of the treatment to help prevent brittle bones, check with your doctor about how much to take.

You should take a few moments to read the patient package insert provided with your prescription.

If you are using Premarin vaginal cream, apply it as follows:

  1. Remove cap from tube.
  2. Screw nozzle end of applicator onto tube.
  3. Gently squeeze tube from the bottom to force sufficient cream into the barrel to provide the prescribed dose. Use the marked stopping points on the applicator as a guide.
  4. Unscrew applicator from tube.
  5. Lie on back with knees drawn up. Gently insert applicator deeply into the vagina and press plunger downward to its original position.

To cleanse the applicator, pull the plunger to remove it from the barrel, then wash with mild soap and warm water. Do not boil or use hot water.

  • If you miss a dose...Take the forgotten dose as soon as you remember. If it is almost time for the next dose, skip the one you missed and go back to your regular schedule. Never try to "catch up" by doubling the dose.
  • Storage instructions...Store at room temperature.

What side effects may occur?

Side effects cannot be anticipated. If any develop or change in intensity, inform your doctor immediately. Only your doctor can determine whether it is safe to continue taking Premarin.

  • Side effects of conjugated estrogens may include:Abdominal/stomach cramps, bloating, breast pain, enlargement of benign tumors of the uterus (also called fibroids), fluid retention, hair loss, headache, high blood pressure, high blood sugar, irregular vaginal bleeding or spotting, liver problems, nausea and vomiting, vaginal yeast infections
  • Other possible side effects of Cenestin may include:Constipation, increased heartbeat, joint pain, skin tingling

Why should Conjugated estrogens not be prescribed?

Do not take Premarin if you have ever had a bad reaction to it, or have undiagnosed abnormal vaginal bleeding.

Except in certain special circumstances, you should not be given Premarin if you have ever had breast cancer, uterine cancer, or any other "estrogen-dependent" cancer.

Do not take Premarin if you have had any circulation problem involving blood clots, or have had a stroke or heart attack in the past year.

Do not take Premarin if you have liver disease or your liver is not working properly.

Do not use Premarin if you are pregnant or trying to become pregnant.

Special warnings about Conjugated estrogens

For women who have not had a hysterectomy, the risk of endometrial and uterine cancer increases when estrogen-only drugs are used for a long time or taken in large doses. Estrogen therapy can also worsen endometriosis (uterine tissue growing outside the uterus). If you've ever had endometriosis, make sure the doctor is aware of it. If you've had a hysterectomy but still have residual endometriosis, your doctor may want you to use an estrogen/progesterone combination.

Certain studies have shown that women taking estrogen for prolonged periods of time (4 years or more) face an increased risk of breast cancer, and a study by the National Heart, Lung and Blood Institute (NHLBI) has confirmed an increased risk among women taking estrogen/progesterone combinations. Use combination products (and estrogen-only preparations, too) with special caution if you have a family history of breast cancer or have ever had an abnormal mammogram. Be sure to get an annual breast exam from your doctor, and do your own self-examination each month.

The NHLBI study also found an increased risk of dementia for women taking estrogen/progesterone combinations. It's unknown whether this applies to estrogen-only drugs.

Because Premarin can increase the risk of heart attack, stroke, blood clots, and certain estrogen-dependent cancers, contact your doctor right away if you notice any of the following:

Abdominal pain, tenderness, or swellingAbnormal bleeding from the vaginaBreast lumpsCoughing up bloodPain in your chest or calvesSevere headache, dizziness, or faintnessSudden shortness of breathVision changes

Women who take Premarin after menopause are more likely to develop gallbladder disease.

Estrogens such as Premarin can cause hypercalcemia, a severe increase of calcium levels in the blood. Women with breast or bone cancer are especially at risk and should stop taking Premarin immediately if they develop hypercalcemia. In addition, women with the opposite problem—hypocalcemia, or a severe decrease of calcium in the blood—should use Premarin with caution.

Women who have not had a hysterectomy and take estrogen along with progesterone have a lower risk of precancerous endometrial changes. However, you should be aware that estrogen/progesterone combinations could increase "bad" LDL cholesterol and blood sugar levels as well as increase the risk of breast cancer.

There is a slight chance that estrogen therapy could cause an increase in blood pressure. Ask your doctor to check your blood pressure regularly.

If you have high levels of fat in your blood, specifically a high triglyceride level, conjugated estrogens such as Premarin are likely to cause side effects in the pancreas.

Use Premarin with caution if you have a history of liver problems, including jaundice. Call your doctor right away if you develop abdominal pain or yellowing of the skin.

Premarin can alter thyroid function. If you're taking thyroid medication, you may need your dosage adjusted.

Premarin can also cause fluid retention. Use the drug with caution if you have heart or kidney problems, or any other condition that's affected by excess fluid in the body.

Some studies have shown that using estrogen-only drugs, especially for 10 years or more, could increase the risk of ovarian cancer. It's unknown whether this also applies to estrogen/progesterone combinations. Another study showed that certain estrogen/progesterone combinations increased the risk of dementia (e.g., Alzheimer's disease).

Estrogens such as Premarin have been known to make certain conditions worse, including asthma, diabetes, epilepsy, migraine, porphyria (a genetic enzyme deficiency), lupus, and liver tumors.

If you are using Premarin vaginal cream, you should be aware that this product can weaken latex condoms, diaphragms, and cervical caps.

Possible food and drug interactions when taking Conjugated estrogens

If Premarin is taken with certain other drugs, the effects of either could be increased, decreased, or altered. It is especially important to check with your doctor before combining Premarin with the following:

Barbiturates such as phenobarbitalBlood thinnersCarbamazepineClarithromycinDrugs used for epilepsyErythromycinGrapefruit juiceItraconazoleKetoconazoleMajor tranquilizersOral diabetes drugsRifampinRitonavirSt. John's wortSteroid medicationsThyroid preparationsTricyclic antidepressantsVitamin C

Special information if you are pregnant or breastfeeding

If you are pregnant or plan to become pregnant, notify your doctor immediately. Premarin and conjugated estrogens should not be taken during pregnancy because of the possibility of harm to the unborn child. Premarin cannot prevent a miscarriage. Estrogens can decrease the quantity and quality of breast milk, and progestins appear in breast milk. Your doctor may advise you not to breastfeed while you are taking Conjugated estrogens.

Recommended dosage for Conjugated estrogens

Your doctor will start therapy with Conjugated estrogens at a low dose and adjust the dosage according to your response. He or she will want to check you periodically at 3- to 6-month intervals to determine the need for continued therapy.


Hot flashes associated with menopause

The usual starting dosage is 0.3 milligrams daily, taken continuously or in cycles such as 25 days on Premarin and 5 days off.

Tissue degeneration in the vagina

The usual starting dosage is 0.3 milligrams daily, taken continuously or in cycles.

Low estrogen levels due to reduced ovary function

The usual dosage is 0.3 to 0.625 milligrams daily, taken cyclically.

Ovary removal or ovarian failure

The usual dosage is 1.25 milligrams daily, taken cyclically.

Prevention of osteoporosis (loss of bone mass)

The usual starting dosage is 0.3 milligrams daily, taken continuously or in cycles.

Advanced androgen-dependent cancer of the prostate, for relief of symptoms only

The usual dosage is 1.25 to 2.5 milligrams 3 times daily.

Breast cancer (for relief of symptoms only) in appropriately selected women and men with metastatic disease

The suggested dosage is 10 milligrams 3 times daily for a period of at least 3 months. Tell your doctor if you have any unusual bleeding.


Given cyclically for short-term use only.

Degeneration of genital tissue or severe itching in the genital area

The recommended dosage is one-half to 2 grams daily, inserted into the vagina, depending on the severity of the condition. You will use the cream for 3 weeks, then stop for 1 week. Tell your doctor if you notice any unusual bleeding.


Symptoms associated with menopause (hot flashes, night sweats, and vaginal tissue degeneration) or for the prevention of osteoporosis (loss of bone mass)

The usual starting dose for Prempro is one 0.3-milligram/1.5-milligram tablet once a day. If this dose proves insufficient, your doctor may increase the dose to one 0.625-milligram/0.25- or 0.5-milligram tablet once a day.

For Premphase therapy, follow a 28-day cycle. Take 1 maroon Premarin tablet (equal to 0.625 milligrams estrogen) every day for the first 14 days; on the 15th day, begin taking 1 light-blue tablet (equal to 0.625 milligrams estrogen/5 milligrams progesterone) daily.


The usual starting dose is 0.45 milligrams a day. If this proves insufficient, the doctor may gradually increase the dose up to a maximum of 1.25 milligrams daily.


Any medication taken in excess can have serious consequences. If you suspect an overdose of Premarin, seek medical attention immediately.

  • Symptoms of conjugated estrogen overdose may include:Nausea, vomiting, withdrawal bleeding
  • Conjugated Estrogens MedFacts Consumer Leaflet (Wolters Kluwer)
  • Cenestin Advanced Consumer (Micromedex) - Includes Dosage Information
  • Cenestin MedFacts Consumer Leaflet (Wolters Kluwer)
  • Enjuvia MedFacts Consumer Leaflet (Wolters Kluwer)
  • Enjuvia Consumer Overview
  • Premarin Prescribing Information (FDA)
  • Premarin Consumer Overview

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