Conjugated oestrogens (Premarin)
How does it work?
Premarin tablets contain conjugated oestrogens as the active ingredient. These are a naturally occuring form of the main female sex hormone, oestrogen.
Womens ovaries gradually produce less and less oestrogen in the period up to the menopause, and oestrogen blood levels decline as a result. The declining levels of oestrogen can cause distressing symptoms, such as irregular periods, hot flushes, night sweats, mood swings and vaginal dryness or itching.
Oestrogen (in this case in the form of conjugated oestrogens) can be given as a supplement to replace the falling levels in the body and help reduce these distressing symptoms of the menopause. This is known as hormone replacement therapy (HRT). HRT is usually only required for short-term relief from menopausal symptoms and its use should be reviewed at least once a year with your doctor.
Premarin tablets are a continuous, oestrogen-only form of HRT. As they only contain oestrogen, they are most suitable for women who have had a hysterectomy. Women who have not had a hysterectomy should also be prescribed a progestogen medicine to take with this medicine for the last 12 to 14 days of each 28-day pack. This is because oestrogen stimulates the growth of the womb lining (endometrium), which can lead to endometrial cancer if the growth is unopposed. A progestogen is given to cause a monthly withdrawal bleed, which opposes oestrogen's effect on the womb lining. This reduces the risk of endometrial cancer, though it does not eliminate this risk entirely. This known as combined HRT. If a woman has had her womb surgically removed (a hysterectomy), endometrial cancer is not a risk, and a progestogen is not necessary as part of HRT (unless the woman has a history of endometriosis).
HRT is also sometimes used to prevent osteoporosis in postmenopausal women. The declining level of oestrogen at menopause can affect the bones, causing them to become thinner and more prone to breaking. Oestrogen supplements help prevent bone loss and fractures that may occur in women in the years after menopause.
However, in December 2003, a review of the available evidence on the risks and benefits of HRT by the Medicines and Healthcare products Regulatory Agency (MHRA) and the Committee on Safety of Medicines (CSM) in the UK, concluded that the risks of using HRT long-term to prevent osteoporosis in women aged over 50 years exceed the benefits. As a result, this medicine should not be used as a first-line option for preventing postmenopausal osteoporosis in women over 50. However, it may be used as a second-line option for women at high risk of fractures who cannot take other medicines that are licensed for this purpose.
Women considered to be at risk of developing fractures following the menopause include those who have had an early menopause, those with a family history of osteoporosis, those who have had recent prolonged corticosteroid therapy (eg prednisolone), those with a small thin frame, and smokers.
You can read more about the risks and benefits of HRT and other medicines for preventing osteoporosis in the factsheets about menopause and osteoporosis linked below.
What is it used for?
- Hormone replacement therapy to relieve symptoms of the menopause
- Second-line option for preventing osteoporosis in postmenopausal women who are at high risk of fractures and cannot take other medicines licensed for preventing osteoporosis.
- Women taking any form of HRT should have regular medical and gynaecological check-ups. Your need for continued HRT should be reviewed with your doctor at least once a year.
- It is important to be aware that all women using HRT have an increased risk of being diagnosed with breast cancer compared with women who don't use HRT. This risk needs to be weighed against the personal benefits to you of taking HRT. There is more detailed information about the risks and benefits associated with HRT in the factsheet about the menopause linked above. You should discuss these with your doctor before starting HRT. Women on HRT should have regular breast examinations and mammograms and should examine their own breasts regularly. Report any changes in your breasts to your doctor or nurse.
- It is important to be aware that women using HRT have a slightly increased risk of stroke and of blood clots forming in the veins (eg deep vein thrombosis/pulmonary embolism) compared with women who don't use HRT. The risk is higher if you have existing risk factors (eg personal or family history, smoking, obesity, certain blood disorders - see cautions below) and needs to be weighed against the personal benefits to you of taking HRT. There is more detailed information about the risks and benefits associated with HRT in the factsheet about the menopause linked above. Discuss these with your doctor before starting treatment.
- The risk of blood clots forming in the veins (thromboembolism) while taking HRT may be temporarily increased if you experience major trauma, have surgery, or are immobile for prolonged periods of time (this includes travelling for over five hours). For this reason, your doctor may recommend that you stop taking HRT for a period of time (usually four to six weeks) prior to any planned surgery, particularly abdominal surgery or orthopaedic surgery on the lower limbs, or if you are to be immobile for long periods. The risk of blood clots during long journeys may be reduced by appropriate exercise during the journey and possibly by wearing elastic hosiery. Discuss this with your doctor.
- Stop taking this medicine and inform your doctor immediately if you experience any of the following symptoms while taking this medicine: stabbing pains or swelling in one leg; pain on breathing or coughing; coughing up blood; breathlessness; sudden chest pain; sudden numbness affecting one side or part of the body; fainting; worsening of epilepsy; migraine or severe headaches; visual disturbances; severe abdominal complaints; increased blood pressure; itching of the whole body; yellowing of the skin or eyes (jaundice); or severe depression.
- This medicine will not usually cause a monthly withdrawal bleed, unless you are also prescribed progestogen tablets to take for the last few days of each month. However, you may experience spotting or breakthrough bleeding during the first few months of treatment. Missing a dose may increase the chance of this. If any breakthrough bleeding or spotting continues after a few months of taking the medicine, or after stopping treatment, you should consult your doctor.
- A woman is considered fertile for two years after her last menstrual period if she is under 50, or for one year if over 50. HRT does not provide contraception for women who fall within this group. If a potentially fertile women is taking HRT but also requires contraception, a non-hormonal method (eg condoms or contraceptive foam) should be used.
Use with caution in
- Close family history of breast cancer (eg mother, sister or grandmother has had the disease)
- History of benign breast lumps (fibrocystic breast disease)
- History of fibroids in the womb
- History of endometriosis
- History of overgrowth of the lining of the womb (endometrial hyperplasia)
- Personal or family history of blood clots in the veins (venous thromboembolism, eg deep vein thrombosis or pulmonary embolism)
- Blood disorders that increase the risk of blood clots in the veins, eg antiphospholipid syndrome, factor V Leiden
- Women taking medicines to prevent blood clots (anticoagulants), eg warfarin
- Long-term inflammation of skin and some internal organs (systemic lupus erythematosus)
- Personal or family history of recurrent miscarriage
- Severe obesity
- Varicose veins
- History of high blood pressure (hypertension)
- Raised levels of fats called triglycerides in the blood (hypertriglyceridaemia)
- History of liver disease, eg liver cancer
- Decreased kidney function
- Heart failure
- History of diabetes
- History of gallstones
- History of migraines or severe headaches
- History of epilepsy
- History of asthma
- History of an ear disorder that may cause hearing loss (otosclerosis)
- History of irregular brown patches appearing on the skin, usually of the face, during pregnancy or previous use of hormone preparations such as contraceptive pills (chloasma). Women with a tendency to this condition should minimise their exposure to the sun or UV light while taking HRT.
Not to be used in
- Known, suspected, or past history of breast cancer
- Known or suspected cancer in which growth of the cancer is stimulated by oestrogen, eg cancer of the lining of the womb (endometrial cancer)
- Untreated overgrowth of the lining of the womb (endometrial hyperplasia)
- Vaginal bleeding of unknown cause
- Women with a blood clot in a vein, eg in the leg (deep vein thrombosis) or in the lungs (pulmonary embolism), or a past history of these conditions
- Women who have recently had a stroke caused by a blood clot
- Women who have recently had a heart attack
- Angina pectoris
- Active liver disease
- History of liver disease when liver function has not returned to normal
- Hereditary blood disorders known as porphyrias
- Rare hereditary problems of galactose intolerance, fructose intolerance, the Lapp lactase deficiency, glucose-galactose malabsorption or sucrase-isomaltase insufficiency (Premarin tablets contain lactose and sucrose).
This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.
Pregnancy and Breastfeeding
Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.
- This medicine should not be used by women who are pregnant or breastfeeding. You should stop taking this medicine and consult your doctor immediately if you get pregnant during treatment.
- A woman is considered fertile for two years after her last menstrual period if she is under 50, or for one year if over 50. HRT does not provide contraception for women who fall within this group. If you could get pregnant while taking this HRT, you should use a non-hormonal method of contraception (eg condoms or contraceptive foam). Seek medical advice from your doctor.
Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Because a side effect is stated here, it does not mean that all people using this medicine will experience that or any side effect.
- Breakthrough bleeding and spotting
- Breast pain, tenderness or enlargement
- Gut disturbances, such as nausea, abdominal pain, bloating, flatulence, indigestion
- Leg cramps
- Weight changes
- Vaginal thrush
- Changes in sex drive
- Rise in blood pressure
- Gall bladder disease
- Swelling of the ankles due to to fluid retention (peripheral oedema)
- Skin reactions such as rash and itch
- Steepening of corneal curvature which may make contact lenses uncomfortable.
- Premenstrual-like symptoms
- Disturbance in liver function
- Irregular brown patches on the skin, usually of the face (chloasma)
- Blood clots in the blood vessels (eg, DVT, pulmonary embolism, heart attack, stroke - see warnings above)
The side effects listed above may not include all of the side effects reported by the drug's manufacturer.For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.
How can this medicine affect other medicines?
It is important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start treatment with this medicine. Similarly, check with your doctor or pharmacist before taking any new medicines while taking this one, to ensure that the combination is safe.
The following medicines may potentially reduce the blood levels and effect of this medicine, which could result in recurrence of symptoms or irregular bleeding:
- antiepileptic medicines such as carbamazepine, phenytoin, phenobarbital and primidone
- barbiturates such as amobarbital
- nevirapine and efavirenz for HIV infection
- protease inhibitors for HIV infection such as ritonavir and nelfinavir
- rifamycin antibiotics such as rifabutin and rifampicin
- the herbal remedy St John's wort (Hypericum perforatum).
Oestrogens may increase the blood level of ropinirole used to treat Parkinson's disease.
Some women with diabetes may need small adjustments in their dose of insulin or antidiabetic tablets while taking this medicine. You should monitor your blood sugar and seek advice from your doctor or pharmacist if your blood sugar control seems to be altered after starting this medicine.
Other medicines containing the same active ingredient