Health Centres - Noristerat
How does it work?
Noristerat injection contains the active ingredient norethisterone enantate, which is a synthetic form of the naturally occurring female sex hormone, progesterone.
Noristerat injection is a depot contraceptive that is given into the muscle of the buttock. The injection forms a reservoir of norethisterone in the muscle, which is then continuously released into the bloodstream over a period of eight weeks.
The norethisterone prevents pregnancy in three ways. It works mainly by preventing the release of an egg from the ovaries (ovulation). In a woman's normal monthly cycle progesterone levels increase following ovulation, and this prevents the release of further eggs. The norethisterone released from the depot contraceptive 'tricks' the body into thinking ovulation has already occured, and this prevents normal ovulation from happening.
Towards the end of the eight weeks that the contraception lasts for, the norethisterone mainly works by its effects on cervical mucus and the lining of the womb. Norethisterone increases the thickness of the natural mucus at the neck of the womb, making it more difficult for sperm to cross from the vagina into the womb. By preventing sperm entering the womb, successful fertilisation of any eggs that are released is less likely. The hormone also changes the quality of the womb lining (endometrium), making it less receptive for any fertilised eggs to implant into.
The contraceptive effect of the injection lasts for eight weeks. The injection should ideally be given in the first five days of a normal menstrual cycle (day one is the first day of your period). If given at this time it is effective straight away, ie no extra contraception is needed. It can also be given at any other time in your cycle if your doctor is sure that you are not pregnant, but you will need to use additional contraception, eg condoms for the first seven days after having the injection.
You can have this injection immediately after giving birth and you will be protected against pregnancy straight away. (This may not be advised if your baby has jaundice and you are breastfeeding - see below for more details.)
If you have had a miscarriage or abortion at under 24 weeks, you can have this injection immediately after and you will be protected against pregnancy straight away. If you have the injection more than seven days after the miscarriage or abortion, you will need to use extra contraception to prevent pregnancy for the first seven days after having the injection.
What is it used for?
Warning!
- It is important that you discuss the pros and cons of Noristerat with your doctor before you are given the injection. The injection cannot be reversed once it has been given and its effects (which may include any unwanted side effects) last for at least eight weeks.
- Noristerat will not protect you against sexually transmitted infections, so you may still need to use condoms as well.
- This medicine must not be given to pregnant women. Women who have not had a menstrual bleed in the eight weeks before the second injection is due should not be given a second injection until a pregnancy test has confirmed that they are not pregnant.
- Consult your doctor if you develop unexplained nausea, vomiting, abdominal pain, fatigue, loss of appetite, darkened urine or yellowing of the eyes or skin (jaundice) during treatment, as these may be signs of liver problems.
- You should not have a second injection of this contraceptive if you experience any of the following after the first injection: liver problems, recurrent severe headaches or migraines; return of earlier depression; large rise in blood pressure; signs of blood clots, eg swelling or stabbing pains in arms or legs, breathlessness, pain on breathing or coughing, chest pain or tightness, weakness or numbness in one side of the body, or fainting; sudden changes to your eyesight, hearing, speech, smell, taste or touch. Consult your doctor immediately if you experience any of these symptoms.
- It is important to be aware that women using hormonal contraceptives appear to have a small increase in the risk of being diagnosed with breast cancer, compared with women who do not use these contraceptives. However, this risk must be weighed against the benefits of using the contraceptive, which can be discussed with your doctor.
Use with caution in
- Heart disease
- A history of blood clots in the blood vessels (thromboembolism)
- Decreased liver function
-
Diabetes
- History of depression
- History of migraine.
Not to be used in
- Known or suspected pregnancy
- Abnormal vaginal bleeding of unknown cause
- History of breast cancer
- History of cancer of the lining of the womb
- History of liver cancer
- Active liver disease
- History of jaundice or generalised itching during a previous pregnancy
- History of an itchy, blistering rash called herpes gestationis during a previous pregnancy
- Deterioration of a disorder causing worsening deafness (otosclerosis) during a previous pregnancy
- Anaemia caused by a hereditary blood disorder where abnormal haemoglobin is produced (sickle cell anaemia)
- Severe diabetes with complications affecting the eyes, kidneys or nerves
- Severe disease of the arteries, eg that has caused a stroke or heart attack
- Disorders of lipid metabolism
-
High blood pressure
- Women with a blood clot in a vein of the leg (deep vein thrombosis) or in the lungs (pulmonary embolism)
- Rare hereditary blood disorders called porphyrias
- Women who know they are going to have an operation in the next twelve weeks and women who are going to be immobile for a long time, eg following an accident.
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.
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 contraceptive must not be given to women who are pregnant. Consult your doctor immediately if you think you could be pregnant after having this injection.
- This contraceptive injection does not affect the production of breast milk and can be given immediately following birth to mothers who are breastfeeding. The hormone does pass into breast milk in tiny amounts, but this is not known to be harmful to healthy infants. However, if your baby has severe or persistant jaundice that requires medical treatment, the manufacturer recommends that you should not breastfeed after having this injection. Seek further medical advice from your doctor.
Side effects
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.
- Changes in menstrual bleeding, eg irregular bleeding or sometimes stopping of bleeding
- Bloating
- Breast discomfort
- Headache
- Dizziness
- Nausea
- Depressed mood
- Reactions at injection site
- Weight gain
- Skin reactions such as rash and itch
The side effects listed above may not include all of the side effects reported by the drug's manufacturer.
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