Anastrozole (INN) (marketed under the trade name Arimidex by AstraZeneca) is an aromatase-inhibiting drug approved for treatment of breast cancer after surgery, as well as for metastasis in both pre- and post-menopausal women. The severity of breast cancer is increased by oestrogen, as sex hormones cause hyperlasia, and differentiation at oestrogen receptor sites. Anastrozole works by inhibiting the synthesis of the hormone oestrogen. The patent on Arimidex by AstraZeneca expired June 2010.
The ATAC (Arimidex, Tamoxifen, Alone or in Combination) trial was an international randomised controlled trial of 9366 women with localized breast cancer who received either anastrozole, tamoxifen, or both for five years, followed by five years of follow-up After more than 5 years the group that received Arimidex (Anastrozole) had significantly better clinical results than the tamoxifen group. The trial suggested that Arimidex is the preferred medical therapy for post-menopausal women with localized breast cancer which is oestrogen receptor (ER) positive. Another study found that the risk of recurrence was reduced by 40%, which also included an increased risk of bone fractures, and that ER negative patients benefited from switching to Anastrozole.
Mechanism of action
Anastrozole binds reversibly to the aromatase enzyme through competitive inhibition, and it inhibits the conversion of androgens to oestrogens in peripheral tissues (outside the central nourvous system (CNS)), and a few CNS sites in various regions within the brain.
Side effects
Bone weakness has been associated with Anastrozole. Women who switched to Arimidex after two years on tamoxifen, they reported twice as many fractures as those who continued to take tamoxifen (2.1% compared to 1%). Bisphosphonates can be sometimes prescribed to prevent the osteoporosis induced by aromatase inhibitors. The level of circulating oestradiol is likely causal in this situation, and not the anastrozole itself, and so the dose will determine likelihood of osteoporosis (oestradiol inhibits osteoclasts, which resorb bone).
Usage in men
Anastrozole has been tested for reducing oestrogens, including oestradiol, in men. Excess oestradiol in men can cause benign prostatic hyperplasia, gynaecomastia, and symptoms of hypogonadism. It can also contribute to a higher risk of stroke, heart attack, chronic inflammation, prostate enlargement and prostate cancer. Some athletes and body builders use anastrozole as part of their steroid cycle to reduce and prevent symptoms of excess oestrogen-gynaecomastia, emotional lability and water retention. Study data suggests dosages of 0.5 mg to 1 mg a day reduce serum oestradiol by approximately 50% in men, which is different from post-menopausal women.
Usage in children
Anastrozole may be used off-label in children with precocious puberty, or children with pubertal gynaecomastia. Following the onset of puberty, the epiphyseal plate begins to close due to an increased amount of oestrogen production escaping local metabolism and spreading to the circulatory system. Arimidex has been shown to help slow this process, and increase adult height prediction in adolescent males treated with protein-based peptide hormones for the treatment of growth hormone deficiency.
Chemical synthesis
The synthesis begins with nucleophilic substitution of two benzylic bromides in α,α'-dibromomesitylene with cyanide, by treatment with potassium cyanide under phase transfer conditions, affording the dinitrile. Exhaustive methylation with methyl iodide and sodium hydride leads to the replacement of the more acidic side chain hydrogen atoms by methyl groups. The treatment with bromine in the presence of benzoyl peroxide leads to the formation of the corresponding benzyl bromide. Reaction of that product with 1,2,4-triazole in the presence of a base completes the synthesis of the aromatase inhibitor.
Information specific to: Arimidex 1mg tablets when used in Breast cancers.
Arimidex is a medicine which is used in breast cancer. Arimidex contains Anastrozole. It is supplied by AstraZeneca UK Limited.
Arimidex 1mg once daily
Mode of Action
Arimidex prevents the production of specific types of hormones in the human body. It is used to treat breast cancer in women who have already gone through the menopause. Arimidex is only used to treat breast cancers which are sensitive to either oestrogen or progesterone hormones. It is not suitable for children or for treating cancers which are not hormone sensitive.
Suitability
Arimidex is not suitable for everyone, and some people must never use it. Other people must only use it with special care.
Your doctor may only prescribe this medicine with special care or may not prescribe it at all if you:
- are allergic or sensitive to or have had a reaction to any of the ingredients in the
medicine
- are pregnat
- breast-feeding
- pre-menopausal
- have galactose intolerance
- have growth problems
- have liver problems
- have glucose-galactose malabsorption problems
- have kidney problems
- have Lapp lactase deficiency
- have osteoporosis (weak bones) or have risk factors for developing osteoporosis
- have risk factors for developing Carpal Tunnel Syndrome
Your doctor may also only prescribe Anastrozole with special care or may not prescribe it at all for a child or an adolescent.
As part of the process of assessing suitability to take Arimidex, your doctor may also arrange the following tests:
- to determine whether or not the medicine is suitable and whether it must be prescribed with extra care
- to check that this medicine is not having any undesired effects
Over time, it is possible that Arimidex can become unsuitable for some people, or they may become unsuitable for it. If at any time it appears that Arimidex has become unsuitable, it is important that you contact your doctor straight away.
Alcohol
Alcohol can interact with certain medications. In the case of Arimidex, there are no known interactions between alcohol and Arimidex.
Diet
Medications can interact with certain foods. In some cases, this may be harmful and your doctor may advise you to avoid certain foods.
In the case of Anastrozole, there are no specific foods which you must exclude from your diet when taking the drug.
Driving and operating machinery
When taking any medicine, you must be aware that it might interfere with your ability to drive or operate machinery safely.
In the case of Arimidex, this medication may affect your ability to drive or operate machinery and you should see how Arimidex affects you, before you judge whether you are safe to drive or operate machinery. If you are in any doubt about whether you should drive or operate machinery, talk to your doctor first.
Family planning and pregnancy
Most medicines, in some way, can affect the development of a baby in the womb. The effect on the baby differs between different drugs, and also depends on the stage of pregnancy that a woman has reached when taking Anastrozole.
In the case of Arimidex, women who are pregnant must not take Arimidex, as it is not suitable during pregnancy. It is very important that you seek urgent medical advice if you become pregnant or think you have become pregnant while taking Anastrozole.
If you are planning to become pregnant, you must discuss your personal circumstances with your doctor so that together you can make a decision about what treatment you may need during your pregnancy.
Arimidex 1mg once daily
Breast feeding
Certain drugs can pass into breast milk and may reach your baby through breast-feeding.
In the case of Arimidex, women who are breast-feeding must not take this medicine. Before you have your baby, you must discuss breast-feeding with your doctor or midwife. If you wish to breast-feed, then you must discuss with your doctor whether there are any other medications you could take that would also allow you to breast-feed. You must not stop this medicine without taking advice from your doctor.
Taking other medicines
If you are taking more than one medicine, they may interact with each other. At times, your prescriber may decide to use medicines which interact with each other, in other cases this may not be appropriate.
The decision to use drugs which interact between them, depends on your specific circumstances. Your doctor may decide to use medicines which interact, if it is believed that the benefits of taking the medicines together outweigh the risks. In such cases, it may be necessary to alter your dose or monitor you more closely.
You must inform your doctor about the names of all the medicines that you are taking, so that they can consider all possible interactions. This includes all the medicines which have been prescribed by your family doctor (GP), hospital doctor, dentist, nurse, health visitor, midwife or pharmacist. You must also tell your doctor about drugs which you have bought over the counter without prescriptions.
Tamoxifen may interact with Arimidex.
The following types of medicine may interact with Arimidex:
- cytochrome P450 enzyme inhibitors
- medicines similar to luteinizing hormone releasing hormone
- oestrogens
If you are taking Arimidex and one of the above medicines or types of medicines, make sure your prescriber is informed about it.
Complementary preparations and vitamins
Medicines may interact with complementary preparations and vitamins. In general, there is not much information available about interactions between medicines and complementary preparations or vitamins.
If you are planning to take or are already taking any complementary preparations and vitamins, you must ask your doctor whether there are any known interactions with Arimidex.
Your doctor can advise you whether it is appropriate for you to take combinations which are known to interact. They can also discuss with you the possible effect which the complementary preparations and vitamins may have on your condition.
If you experience any unusual effects while taking Anastrozole in combination with complementary preparations and vitamins, you must inform immediately your doctor.
Ingredients of Arimidex
Medicines contain active ingredients. They may also contain other, additional ingredients which help ensure the stability, safety and effectiveness of the medicine. They are also added to improve the medicine's taste and appearance, and to make it easier to take. Some may be used to prolong the life of the medicine.
You must check that you are able to take the ingredients in your medicine, especially if you have any allergies.
Arimidex contains:
- anastrozole
- macrogol 300
- hypromellose
- lactose monohydrate
- povidone
- magnesium stearate
- sodium starch glycollate
- titanium dioxide
If you are not able to take any of the ingredients in Arimidex, you should inform your doctor or pharmacist to see if they can suggest an alternative medicine. If you have reacted badly to Arimidex before, do not take Arimidex again. Speak to your doctor, pharmacist or specialist cancer nurse as soon as possible.
How to take Arimidex
Some medicines have specific instructions about how to take them. This is because they work better when they are taken correctly. These instructions can include getting the right dose and special instructions for preparing the medicine. You must make sure that you follow any specific instructions given to you by your doctor, or that are in the Patient Information Leaflet which comes with this medicine.
If you are having problems taking Arimidex, you must speak to your doctor or pharmacist. They may be able to give you advice on other ways to take your medicine, or other similar drugs which are easier for you to take.
When to take Arimidex
Some medicines work best if they are taken at a specific time of the day. Getting the most from your medicine can also be affected by what you eat, when you eat, and the times at which you take other medicines.
Make sure you follow any specific instructions given to you by your doctor or that are in the Patient Information Leaflet which comes with Arimidex.
Make sure you follow any specific instructions given to you by your doctor or that are in the Patient Information Leaflet which comes with Arimidex.
Taking too much of your medicine (Overdose)
Taking extra doses of some medicines can be harmful. In some cases even one extra dose may cause you problems. If you take extra doses of your medicine, you should get medical advice immediately. You may need a test to assess the effect of taking extra doses. This is because the effects of taking too much medicine are very complex, so it is very important that you seek medical advice immediately.
Make sure you take all of your medicine containers with you, if you are advised to go to hospital.
Stopping Arimidex
Suddenly stopping Arimidex may cause your original condition to return. This is why you must talk to your doctor/oncologist if you are having any problems taking your medicine.
If you are not having any problems taking Arimidex, then do not stop taking it, even if you feel better, unless advised to do so by your doctor. If you are in any doubt, contact your doctor for further advice.
Looking after Arimidex
The instructions on how you should keep your medicine are on the pharmacy label. You must keep your medicine in the original container. This will help to keep your medication in the best condition and also allow you to check the instructions.
Do not take Arimidex if the packaging appears to have been tampered with, or if the medicine shows any signs of damage. Make sure that the medicine is out of the sight and reach of children.
Do not take Arimidex if the packaging appears to have been tampered with, or if the medicine shows any signs of damage. Make sure that the medicine is out of the sight and reach of children.
Arimidex 1mg once daily
Side-effects of Arimidex
A medicine is only made available to the public if the clinical trials have shown that the benefits of taking the medicine outweigh the risks. Once a medicine has been licensed, information on the medicine's effects, both intended and unintended, is continuously recorded and updated.
Some side-effects may be serious while others may only be a mild inconvenience. Everyone's reaction to a medicine is different. It is difficult to predict which side effects you may have from taking a particular medicine, or whether you will have any side effects at all. The important thing is to inform your doctor/oncologist, pharmacist or specialist nurse, if you are having problems with your medication.
Very common side effects of Arimidex (More than 10% of patients who take Arimidex):
- arthritis
- hot flushes
- osteoporosis
- weakness
- nausea
- headaches
- joint pain or stiffness
- skin rash or rashes
Common side effects of Arimidex (More than 1% of patients taking Arimidex):
- Bone pain
- allergic reactions
- hair loss
- diarrhoea
- abnormal laboratory test results
- carpal tunnel syndrome
- loss of appetite
- high levels of cholesterol in the blood
- sleepiness
- vomiting
- vaginal bleeding - seek medical advice if bleeding is persistent
- vaginal dryness
Uncommon side effects of Arimidex (More than 0.1% of patients taking Arimidex):
- liver problems
- urticaria
- trigger finger
Rare side effects of Arimidex (More than 0.01% of patients taking Arimidex):
- anaphylactic reactions
- erythema multiforme
- vasculitis including bruising of the skin
Very rare side effects of Arimidex (More than 0.001% of patients taking Arimidex):
- angioedema
- Stevens-Johnson syndrome
The frequency of these side-effects of Arimidex (Anastrozole) is still not known:
- Cataracts
- Deep vein thrombosis (DVT)
- Pulmonary embolism (PE)
- mood changes
- angina
- bone fractures
- cerebrovascular problems (including stroke)
- endometrial cancer
- heart attack (myocardial infarction - MI)
- heart or blood circulation problems
- lowering of bone mineral density
- thromboembolism
- tiredness
- vaginal discharge
If you feel unwell, or if you have concerns about a side effect of Arimidex, you will need to seek advice from your doctor as soon as possible.
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