Consumer medicine information

What is in this leaflet

This leaflet answers some common questions about TAMOSIN. It does not contain all of the available information.

It does not take the place of talking to your doctor or pharmacist.

All medicines have risks and benefits. Your doctor has weighed the risks of you taking TAMOSIN against the benefits they expect it will have for you.

If you have any concerns about taking this medicine, ask your doctor or pharmacist.

Keep this leaflet with the medicine. You may need to read it again.

What TAMOSIN is used for

TAMOSIN contains the active ingredient tamoxifen (as tamoxifen citrate). Tamoxifen is an anti-oestrogen medicine and is used to counteract the actions of the naturally occurring female sex hormone, oestrogen.

TAMOSIN is used in the treatment of breast cancer.

TAMOSIN blocks the actions of oestrogen. In some types of breast cancer, oestrogen can help the cancer cells to grow.

Ask your doctor if you have any questions about why TAMOSIN has been prescribed for you. Your doctor may have prescribed it for another reason.

This medicine is only available with a doctor's prescription.

TAMOSIN is not addictive.

Before you take it

When you must not take it

Do not take TAMOSIN if you have ever had an allergic reaction to:

• tamoxifen
• lactose. This product contains sugars as lactose.
• any of the other ingredients listed at the end of this leaflet.

Some of the symptoms of an allergic reaction may include shortness of breath, wheezing or difficulty breathing; swelling of the face, lips, tongue or other parts of the body; rash, itching or hives on the skin.

Do not take TAMOSIN if you are pregnant. It may affect your developing baby.

Do not take TAMOSIN after the expiry date printed on the pack.

Do not take TAMOSIN if the packaging is torn or shows signs of tampering or if the tablets do not look quite right.

Before you start to take it

Tell your doctor if you are allergic to any other medicines or any foods, dyes or preservatives.

Tell your doctor if you are pregnant, may be pregnant or plan to become pregnant. Taking TAMOSIN during pregnancy can harm your developing baby. Your doctor will discuss the risks involved.

Tell your doctor if you have not been through menopause. If it is possible that you could become pregnant, you must use a non-hormonal barrier method of contraception, while you are taking TAMOSIN and for two months after you stop taking it.

Tell your doctor if you are breast feeding or plan to breast feed. It is not known if tamoxifen is excreted in breast milk so it is not recommended for use while breast feeding.

Tell your doctor if you have or have had any of the following medical conditions:

• liver problems
• blood clots in legs, lungs, heart or brain
• any unexplained vaginal bleeding or discharge
• blood disorders such as a low platelet count or a low white blood cell count.

It may not be safe for you to take TAMOSIN if you have any of these conditions.

If you have not told your doctor about any of the above, tell them before you start taking TAMOSIN.

Taking other medicines

Tell your doctor if you are taking any other medicines, including any that you buy without a prescription from a pharmacy, supermarket or health food shop.

Some medicines and TAMOSIN may interfere with each other. These include coumarin type anticoagulants used to prevent blood clots, such as warfarin, as an increase in the anticoagulant effect may occur. Where co-administration is initiated by your doctor, careful monitoring is required.

These medicines may be affected by TAMOSIN or may affect how well it works. You may need to take different amounts of your medicine or you may need to take different medicines.

Avoid taking drugs containing paroxetine, fluoxetine, quinidine, cinacalcet, bupropion, oestrogens, thiazide diuretics, mitomycin and rifampicin.

Your doctor and pharmacist have more information on medicines to be careful with or avoid while taking TAMOSIN.

How to take it

How much to take

Your doctor will advise you on what your dose will be.

The usual dose is 20 mg (one tablet) daily. Some people may need to take 40 mg (two tablets) daily. Your doctor will tell you if this is necessary.

How to take it

Swallow the tablets whole with a full glass of water.

Do not crush or chew the tablets.

When to take it

Take TAMOSIN at about the same time each day.

It does not matter if you take TAMOSIN before, with or after food.

How long to take it

Keep taking TAMOSIN for as long as your doctor tells you to.

If you forget to take it

If it is almost time for your next dose, skip the dose you missed and take your next dose when you are meant to.

Otherwise, take it as soon as you remember, and then go back to taking your medicine as you would normally.

Do not take a double dose to make up for the dose that you missed.

If you are not sure what to do, ask your doctor or pharmacist.

If you take too much (overdose)

Immediately telephone your doctor or the Poisons Information Centre (phone 13 11 26) for advice, or go to Accident and Emergency at your nearest hospital, if you think that you or anyone else may have taken too much TAMOSIN. Do this even if there are no signs of discomfort or poisoning. You may need urgent medical attention.

Symptoms of overdose may include problems with heart rhythm.

While you are taking it

Things you must do

Tell any other doctors, dentists and pharmacists that are treating you that you are taking TAMOSIN, especially if you are about to be started on any new medicines.

Have regular eye examinations.

Beware of other medicines that are known to increase the risk for eye disorders.

If you experience fatigue while taking tamoxifen, exercise caution when driving or operating machinery.

Tell your doctor immediately if you:

• become pregnant while taking TAMOSIN, or within two months of stopping treatment
• notice any unusual vaginal bleeding or discharge
• pelvic pain or pressure
• notice any changes to your eyesight
• notice any symptoms of blood disorders such as unusual bruising or bleeding.

Tell your doctor that you are taking TAMOSIN if you are about to have any blood tests.

It is very important to keep all of your doctor's appointments, so that your progress can be checked.

Things you must not do

Do not get pregnant while you are taking TAMOSIN.

Do not take TAMOSIN to treat any other complaints unless your doctor tells you to.

Do not give TAMOSIN to anyone else, even if they have the same condition as you.

Do not stop taking TAMOSIN or lower the dosage without checking with your doctor.

Side effects

Tell your doctor as soon as possible if you do not feel well while you are taking TAMOSIN.

All medicines can have side effects. Sometimes they are serious, most of the time they are not. You may need medical treatment if you get some of the side effects.

Ask your doctor or pharmacist to answer any questions you may have.

Tell your doctor if you notice any of the following and they worry you:

• hot flushes
• nausea, vomiting or stomach upset
• headache
• skin rash, itching
• dizziness or lightheadedness
• depression
• swelling of the hands, feet or ankles
• itching around the vagina or genitals
• leg cramps
• hair thinning or hair loss
• aching muscles or muscle tenderness not caused with exercise.

Tell your doctor immediately if you notice any of the following:

• problems with your eyesight
• unusual vaginal bleeding or discharge
• changes in your menstrual periods
• unusual bruising or bleeding
• pain in the bones or at the site of your cancer
• yellowing of the skin and/or eyes
• frequent infections such as fever, severe chills, sore throat or mouth ulcers
• increase in blood calcium levels, therefore you may notice this as nausea, vomiting and excessive thirst.
• symptoms of a blood clot or if you notice a clot, especially in your arms or legs.

This list is not exhaustive, please refer to your doctor or pharmacist for a more complete list.

Cases of optic nerve diseases have been reported in patients receiving tamoxifen and, in a small number of cases, blindness has occurred.

Tell your doctor if you have any unusual vaginal bleeding or other gynaecological symptoms (such as pelvic pain or pressure) when you are taking TAMOSIN or anytime afterwards. This is because a number of changes to the lining of the womb (endometrium) may occur, some of which may be serious and could include cancer.

Increased risk of blood clots and ovarian cysts (in premenopausal women) have been reported in patients taking TAMOSIN.

Rarely, an increased level of triglycerides (increased levels of fats in the blood) sometimes with pancreatitis (pain or tenderness in the upper abdomen) has been reported in patients taking TAMOSIN.

Tell your doctor if you notice anything else that is making you feel unwell, even if you think the problems are not connected with this medicine and are not referred to in this leaflet.

Other side effects not listed above may also occur in some people.

Do not be alarmed by this list of possible side effects. You may not experience any of them.

After taking it

Storage

Keep TAMOSIN in a cool, dry place, protected from light, where the temperature stays below 25°C.

Keep the tablets in the bottle until it is time to take them.

Do not store it in the bathroom or near a sink. Do not leave it on a windowsill or in the car. Heat or dampness can destroy some medicines.

Keep it where children cannot reach it. A locked cupboard at least one-and-a-half metres above the ground is a good place to store medicines.

Disposal

If your doctor tells you to stop taking this medicine or the expiry date has passed, ask your pharmacist what to do with any medicine left over.

Product description

What it looks like

TAMOSIN tablets are round white tablets with “20” debossed on one side.

Available in a carton containing a plastic bottle containing 30 or 60 tablets.

Not all pack sizes are supplied.

Ingredients

Active ingredient:

Each TAMOSIN tablet contains tamoxifen citrate, equivalent to 20 mg of tamoxifen.

Inactive ingredients:

• maize starch
• lactose monohydrate
• povidone
• sodium starch glycollate
• magnesium stearate.

TAMOSIN tablets do not contain gluten, sucrose, tartrazine or any other azo dyes.

Sponsor

Orion Pharma (Aus) Pty Limited
Level 24, Tower 3
300 Barangaroo Avenue, Sydney,
NSW 2000, Australia
Telephone: 1800 861 913

Australian Registration Number:
AUST R 43527.

This leaflet was revised in September 2022.

Published by MIMS October 2022

1 Name of Medicine

Tamoxifen citrate.

2 Qualitative and Quantitative Composition

Each Tamosin tablet contains tamoxifen citrate equivalent to 20 mg of tamoxifen.

Excipients with known effect.

3 Pharmaceutical Form

Tablet.
Tamosin is a white, round, convex tablet, 9 mm in diameter with 20 debossed on one side.

4 Clinical Particulars

4.1 Therapeutic Indications

Palliative treatment of breast cancer.

4.2 Dose and Method of Administration

The recommended daily dose of Tamosin is 20 mg. A dose of 40 mg may be used in patients with advanced breast cancer in which no response is seen with the minimal dose.
Response is usually not achieved until after a treatment period of 2 to 3 months.
The current recommended treatment duration is five years; however, the optimum duration has not been established.

Older people.

Method of administration.

4.3 Contraindications

Tamoxifen must not be given during pregnancy. Premenopausal patients must be carefully examined before treatment for breast cancer to exclude the possibility of pregnancy.
Tamoxifen is contraindicated in patients hypersensitive to it.

4.4 Special Warnings and Precautions for Use

An increased incidence of endometrial changes including hyperplasia, endometrial polyps, cancer and uterine sarcoma (mostly malignant mixed Mullerian tumours) have been reported in association with tamoxifen treatment. The incidence and pattern of this increase suggest that the underlying mechanism is related to the oestrogenic properties of tamoxifen. Any patients receiving or having previously received tamoxifen who report abnormal gynaecological symptoms, especially vaginal bleeding or who presents with menstrual irregularities, vaginal discharge and symptoms such as pelvic pain or pressure should be promptly investigated.
Severe cutaneous adverse reactions (SCARs) including Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN), which can be life-threatening or fatal, have been reported in association with tamoxifen treatment. At the time of prescription patients should be advised of the signs and symptoms and monitored closely for skin reactions. If signs and symptoms suggestive of these reactions appear, tamoxifen should be withdrawn immediately and an alternative treatment considered (as appropriate). If the patient has developed a serious reaction such as SJS or TEN with the use of tamoxifen, treatment with tamoxifen must not be restarted in this patient at any time.
In patients with hereditary angioedema, tamoxifen may induce or exacerbate symptoms of angioedema.
A number of secondary primary tumours, occurring at sites other than the endometrium and the opposite breast, have been reported in clinical trials, following the treatment of breast cancer patients with tamoxifen. No causal link has been established and the clinical significance of these observations remains unclear.
During treatment periodic check-ups including gynaecological examination focusing on endometrial changes are recommended of a frequency and nature adapted to the individual woman and modified according to her clinical needs.
When starting tamoxifen therapy the patient should undergo an ophthalmological examination. Other concomitant medications that are known to increase risk for eye disorders (e.g. retinopathy) should be taken into account. Cases of visual disturbances, including infrequent reports of corneal changes, and common reports of retinopathy have been described in patients receiving Tamosin therapy. Cataracts have commonly been reported in association with the administration of Tamosin. Repeated ophthalmologic examination is essential in patients receiving tamoxifen treatment. If visual changes (cataracts and retinopathy) occur while on tamoxifen therapy urgent ophthalmological investigation is necessary. Most ocular adverse reactions are reversible after tamoxifen discontinuation.
There is evidence that treatment with tamoxifen may increase the risk of thromboembolic events, including stroke, deep vein thrombosis, and pulmonary embolism. In patients with breast cancer, prescribers should obtain careful histories with respect to the patient's personal and family history of venous thromboembolism (VTE). Severe obesity, increasing age and all other risk factors for VTE should be evaluated. If suggestive of a prothrombotic risk, patients should be screened for thrombophilic factors. Patients who test positive should be counselled regarding their thrombotic risk. The decision to use tamoxifen in these patients should be based on the overall risk to the patient. Long-term anticoagulant prophylaxis may be justified for some patients with breast cancer who have multiple risk factors for VTE.
All patients should be advised to contact their doctors immediately, if they become aware of any symptoms of venous thromboembolism. Patients should be advised to seek immediate medical attention if they become aware of any symptoms of thromboembolic events; in such cases, tamoxifen therapy should be stopped and appropriate antithrombosis measures initiated. In patients receiving tamoxifen for breast cancer, the decision to re-start tamoxifen should be made with respect to the overall risk for the patient. In selected patients, the continued use of tamoxifen with prophylactic anticoagulation may be justified. Co-administration with cytotoxic agents increases the risk for thromboembolic events.
Tamosin should be used cautiously in patients with existing leucopenia or thrombocytopenia. Leucopenia has been observed following the administration of Tamosin sometimes in association with anaemia and/or thrombocytopenia. Neutropenia has been reported on rare occasions; this can sometimes be severe and rarely cases of agranulocytosis have been reported. Decreases in platelet counts, usually to 50,000 to 100,000/mm³, infrequently lower, have been occasionally reported in patients taking Tamosin for breast cancer. Periodic complete blood counts, including platelet counts, may be appropriate.
In delayed microsurgical breast reconstruction Tamosin may increase the risk of microvascular flap complications.

Use in premenopausal women.

Use in the elderly.

Paediatric use.

Effects on laboratory tests.

4.5 Interactions with Other Medicines and Other Forms of Interactions

When tamoxifen is used in combination with coumarin type anticoagulants, a significant increase in anticoagulant effect may occur. In the case of concomitant treatment particularly during the initial phase thorough monitoring of the coagulation status is mandatory.
In the literature it has been shown that CYP2D6 poor metabolisers have a lowered plasma level of endoxifen, one of the most important active metabolites of tamoxifen. Concomitant medications that inhibit CYP2D6 may lead to reduced concentrations of the active metabolite endoxifen. Therefore, potent inhibitors of CYP2D6 (e.g. paroxetine, fluoxetine, quinidine, cinacalcet or bupropion) should whenever possible be avoided during tamoxifen treatment.
Radiation recall has been reported very rarely in patients on tamoxifen who have received prior radiotherapy. The reaction is usually reversible upon temporary cessation of therapy and re-challenge may result in a milder reaction. Treatment with tamoxifen was continued in most cases.
Tamoxifen tablets contain lactose monohydrate. Patients with rare hereditary problems of galactose intolerance, total lactase deficiency or glucose-galactose malabsorption should not take this medicine.
Thrombocyte aggregation inhibitors should not be combined with tamoxifen in order to avoid bleeding during possible thrombocytopenic period.
The use of tamoxifen in combination with aromatase inhibitor (such as anastrozole) as adjuvant therapy has not shown improved efficacy compared with tamoxifen alone.
Hormone preparations, particularly oestrogens (e.g. oral contraceptives) should not be combined with tamoxifen because a mutual decrease in effect is possible.
Medicaments which decrease renal calcium excretion, e.g. thiazide diuretics, may increase the risk of hypercalcaemia.
There are two case reports where concomitant use of tamoxifen and tegafur was observed to induce chronic active hepatitis and liver cirrhosis.
Concomitant use of mitomycin (even in small doses) and tamoxifen increases risk for haemolytic-uremic syndrome, anaemia and thrombocytopenia. Concomitant use should be avoided.
Tamoxifen is mainly metabolised by CYP3A4. Caution is required when coadministered with known inhibitors or inducers (such as rifampicin) of CYP3A4 enzymes.
An increased risk of thromboembolic events may occur if Tamosin is administered in combination with cytotoxic agents. Because of this increase in risk of VTE, thrombosis prophylaxis should be considered for these patients for the period of concomitant chemotherapy.

4.6 Fertility, Pregnancy and Lactation

Effects on fertility.

4.7 Effects on Ability to Drive and Use Machines

Tamoxifen is unlikely to impair the ability of patients to drive or operate machinery. However, fatigue has been reported with the use of tamoxifen and caution should be observed when driving or operating machinery while such symptoms persist.

4.8 Adverse Effects (Undesirable Effects)

When side effects are severe, it may be possible to control them by a simple reduction of dosage (to not less than 20 mg/day) without loss of control of the disease. If side effects do not respond to this measure, it may be necessary to stop the treatment.
The adverse reactions which have been reported are of two types:
those associated specifically with the antioestrogenic action of the drug, e.g. hot flushes, vaginal bleeding, vaginal discharge, pruritus vulvae, tumour pain and tumour flare;
those of a more general nature, e.g. gastrointestinal intolerance, headache, lightheadedness, skin rash and, occasionally, fluid retention and alopecia.
List of possible adverse drug reactions reported in association of tamoxifen therapy are tabulated in Table 1.
Infrequent cases of endometrial, ocular and haematological adverse effects have been reported (see Section 4.4 Special Warnings and Precautions for Use). When such adverse reactions are severe, it may be possible to control them by a simple reduction in dosage (within the recommended dosage range) without loss of control of the disease. If adverse reactions do not respond to this measure, it may be necessary to stop the treatment.
There may be an increased tendency to thrombophlebitis. When Tamosin is used in combination with cytotoxic agents there is increased risk of thromboembolic events occurring.
Haemorrhagic episodes may occur.

Reporting suspected adverse effects.

4.9 Overdose

On theoretical grounds, an overdose would be expected to cause enhancement of the antioestrogenic side effects mentioned above. Observations in animals show that extreme overdosage (100 to 200 times the equivalent of the recommended daily human dose) may produce oestrogenic effects.
It has been reported in the literature that tamoxifen given at several times the recommended dose is associated with a prolongation of the QT interval of the ECG.

Treatment.

5 Pharmacological Properties

5.1 Pharmacodynamic Properties

Mechanism of action.

Clinical trials.

5.2 Pharmacokinetic Properties

Absorption.

Bioavailability.

Distribution.

Protein binding.

Metabolism.

Excretion.

Half-life.

Clinical implications of pharmacokinetic data.

5.3 Preclinical Safety Data

Genotoxicity.

Carcinogenicity.

6 Pharmaceutical Particulars

6.1 List of Excipients

Each tablet contains the following inactive ingredients: lactose monohydrate, magnesium stearate, povidone, sodium starch glycollate and maize starch.

6.2 Incompatibilities

Incompatibilities were either not assessed or not identified as part of the registration of the medicine. Please see Section 4.5 Interactions with Other Medicines and Other Forms of Interactions.

6.3 Shelf Life

3 years.

6.4 Special Precautions for Storage

Store below 25°C. Protect from light.

6.5 Nature and Contents of Container

HDPE plastic bottles containing 30 or 60 tablets.
Not all pack sizes are marketed.

6.6 Special Precautions for Disposal

In Australia, any unused medicine or waste material should be disposed of in accordance with local requirements.

6.7 Physicochemical Properties

Tamoxifen citrate is 2-[4-[(Z)-1, 2-diphenylbut-1-enyl] phenoxy]-N, N-dimethylethanamine dihydrogen 2-hydroxypropane-1,2,3- tricarboxylate. C₂₆H₂₉NO.C₆H₈O₇.
Tamoxifen citrate is a white or almost white polymorphic, crystalline powder. The molecular weight is 563.6 g/mol.

Chemical structure.

CAS number.

7 Medicine Schedule (Poisons Standard)

S4 (Prescription Only Medicine).

Summary Table of Changes