Soltamox 10mg/5ml Oral Solution

Each 5ml dose of oral solution contains tamoxifen 10mg (as tamoxifen citrate)

Excipients:

Ethanol - 750mg per 5ml

Liquid sorbitol (non-crystallising) (E420) - 1g per 5ml

For a full list of excipients, see section 6.1.

Oral Solution

A clear colourless liquid

- Adjuvant treatment of oestrogen-receptor positive early breast cancer

- Treatment of oestrogen-receptor positive locally advanced or metastatic breast cancer

Adjuvant treatment of breast cancer, Adults (including elderly):

The recommended dose is 20mg, given either in divided doses twice daily or as a single dose once daily. The current recommended treatment duration is five years; however the optimum duration has not been established.

Treatment of locally advanced or metastatic breast cancer:

The recommended dose is 20mg to 40mg, given either in divided doses twice daily or as a single dose once daily.

Children: Not applicable.

Pregnancy and lactation

Hypersensitivity to tamoxifen or to any of the excipients

Concurrent anastrozole therapy (see section 4.5)

Premenopausal patients must be carefully examined before treatment to exclude pregnancy.

Women should be informed of the potential risks to the foetus, should they become pregnant whilst taking tamoxifen; or within two months of cessation of therapy.

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.

Menstruation is suppressed in a proportion of premenopausal women receiving tamoxifen for the treatment of breast cancer.

Any patients who have received tamoxifen therapy and have reported abnormal vaginal bleeding or patients presenting with menstrual irregularities, vaginal discharge and pelvic pressure or pain should undergo prompt investigation due to the increased incidence of endometrial changes including hyperplasia, polyps, cancer and uterine sarcoma (mostly malignant mixed Mullerian tumours) which has been reported in association with tamoxifen treatment. The underlying mechanism is unknown, but may be related to the oestrogenic-like effect of tamoxifen.

Before initiating tamoxifen a complete personal history should be taken. Physical examination (including pelvic examination) should be guided by the patients past medical history and by the 'contraindications' and 'special warnings and precautions for use' warnings for use for tamoxifen. During treatment periodic check-ups including gynaecological examination focussing 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. If visual changes (cataracts and retinopathy) occur while on tamoxifen therapy it is urgent that an ophthalmological investigation be performed, because some of such changes may resolve after cessation of treatment if recognised at an early stage.

In cases of severe thrombocytopenia, leucocytopenia or hypercalcaemia, individual risk-benefit assessment and thorough medical supervision are necessary.

Venous thromboembolism:

• A 2-3-fold increase in the risk for VTE has been demonstrated in healthy tamoxifen-treated women (see section 4.8).

• Caution is advised regarding use of tamoxifen in patients who screen positive for thrombophilic factors; occasionally concomitant prophylactic anticoagulation may be justified (see section 4.5).

•VTE risk is further increased by severe obesity, increasing age and concomitant chemotherapy (see section 4.5). Long-term anti-coagulant prophylaxis may be justified for some patients with breast cancer who have multiple risk factors for VTE.

• Surgery and immobility: Tamoxifen treatment should only be stopped if the risk of tamoxifen-induced thrombosis clearly outweighs the risks associated with interrupting treatment. All patients should receive appropriate thrombosis prophylactic measures.

• Patients should be advised to seek immediate medical attention if they become aware of any symptoms of VTE; in such cases, tamoxifen therapy should be stopped and appropriate anti-thrombosis measures initiated.

• In the above all cases, the risks and benefits to the patient of tamoxifen therapy must be carefully considered.

The blood count including thrombocytes, liver function test and serum calcium should be controlled regularly.

Assessment of triglycerides in serum may be advisable because in most published cases of severe hypertriglyceridemia dyslipoproteinemia was the underlying disorder.

This product contains 19%v/v ethanol, i.e. 750mg per dose equivalent to 19ml of beer or 8ml of wine per dose. It is harmful for those suffering from alcoholism. It should be taken into account in high-risk groups such as patients with liver disease or epilepsy. It may modify or increase the effect of other medicines.

This product contains glycerol which may cause headache, stomach upset and diarrhoea.

This product also contains sorbitol. Patients with rare hereditary problems of fructose intolerance should not take this medicine.

Tamoxifen is not intended for use in children.

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 (see section 5.2).

Concomitant medications that inhibit (CYPD2D6 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 (see section 4.5 and 5.2).

Coumarin-type anti-coagulants:

When used in combination with tamoxifen solution 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.

Thrombocyte aggregation inhibitors:

In order to avoid bleeding during a possible thrombocytopenic interval thrombocyte aggregation inhibitors should not be combined with tamoxifen.

Cytotoxic agents:

When used in combination with tamoxifen solution there is increased risk of thromboembolic events occurring (see also Sections 4.4 and 4.8). Because of this increase in risk of VTE, thrombosis prophylaxis should be considered for these patients for the period of concomitant chemotherapy. Tamoxifen and its metabolites have been found to be inhibitors of hepatic cytochrome p-450 mixed function oxidases. The effect of tamoxifen on metabolism and excretion of other antineoplastic drugs, such as cyclophosphamide and other drugs that require mixed function oxidases of activation, is not known.

Anastrozole:

The use of tamoxifen in combination with anastrozole as adjuvant therapy has not shown improved efficacy compared with tamoxifen alone.

Bromocriptine:

Tamoxifen increases the dopaminergic effect of bromocriptine.

Hormone preparations:

Hormone preparations, particularly oestrogens (e.g. oral contraceptives) should not be combined with tamoxifen because a mutual decrease in effect is possible.

As tamoxifen is metabolised by cytochrome P450 34A, care is required when co-administered with drugs known to induce this enzyme, such as rifampicin, as tamoxifen levels may be reduced. The clinical relevance of this reduction is unknown.

Plasma concentrations of tamoxifen may be increased by concomitant treatment with CYP3A4 inhibitors.

Pharmacokinetic interaction with CYP2D6 inhibitors, showing a reduction in plasma level of an active tamoxifen metabolite, 4-hydroxy-N-desmethyltamoxifen (endoxifen), has been reported in the literature. The relevance of this to clinical practice is not known.

Pharmacokinetic interaction with CYP2D6 inhibitors, showing a 65-75% reduction in plasma levels of one of the more active forms of the drug, i.e. endoxifen, has been reported in the literature. Reduced efficacy of tamoxifen has been reported with concomitant usage of some SSRI antidepressants (e.g. paroxetine) in some studies. As a reduced effect of tamoxifen cannot be excluded, co-administration with potent CYP2D6 inhibitors (e.g. paroxetine, fluoxetine, quinidine, cinacalcet or bupropion) should whenever possible be avoided (see section 4.4 and 5.2).

Pregnancy:

There are only data from a small number of women who have been exposed to tamoxifen during pregnancy. Although no causal relationship has been established, only a small number of spontaneous abortions, birth defects and foetal deaths in women treated with tamoxifen during pregnancy have been reported.

Animal studies have shown reproduction toxicity (see section 5.3). Although the clinical relevance of the observed preclinical effects is unknown, some of them, especially vaginal adenosis, are similar to those seen in young women who were exposed to DES in utero and who have a 1 in 1000 risk of developing clear cell carcinoma of the vagina or cervix. Such exposure has not been reported to cause subsequent vaginal adenosis or clear cell carcinoma of the vagina or cervix in the small number of young women known to have been exposed in utero to tamoxifen.

Since the use of tamoxifen during pregnancy is contraindicated, women should be advised not to become pregnant whilst taking tamoxifen and within two months after stopping tamoxifen medication and should use barrier or other non hormonal contraceptive methods if sexually active.

Lactation:

It is not known whether tamoxifen is excreted into breast milk. Therefore, tamoxifen treatment is contraindicated during breast-feeding. Tamoxifen inhibits lactation in humans and no rebound lactation was observed after completion of therapy.

No studies on the effects of the ability to drive and use machines have been performed.

Since visual disturbances and light-headedness have been observed commonly with the use of tamoxifen, caution is advised when driving or using machines. The amount of alcohol in this product may impair the ability to drive or use machines.

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

Endometriosis has been reported.

Leucopenia has been observed following the administration of tamoxifen, sometimes in association with anaemia and/or thrombocytopenia.

When undesirable events are severe it may be possible to control them by a simple reduction of dosage without loss of control of the disease. If undesirable events do not respond to this measure, it may be necessary to cease treatment.

At doses of 160mg/m² daily and higher, changes in ECG (QT-prolongation) and at doses of 300 mg/m² daily, neurotoxicity (tremor, hyperreflexia, gait disorders, and dizziness) occurred.

Overdosage of tamoxifen will increase the anti-oestrogenic effects. There is no specific antidote to overdosage and treatment should therefore be symptomatic.

Pharmacotherapeutic group: Hormone antagonists and related agents

ATC Code: L02B A01

Tamoxifen is a non-steroidal anti-oestrogen and inhibits the effects of endogenous oestrogen, probably by binding with oestrogen receptors. Tamoxifen competes for the binding sites with estradiol and by occupying the receptor reduces the amount of receptor available for endogenous estradiol. Tamoxifen also prevents the normal feedback inhibition of oestrogen synthesis in the hypothalamus and in the pituitary.

Tamoxifen decreases cell division in oestrogen-dependent tissues. In metastatic breast cancer, partial or complete remissions were observed in 50-60% of cases, particularly in bone and soft tissue metastases if oestrogen-receptors were found in the tumour. In cases of negative hormone-receptor status, particularly of the metastases only approx. 10% showed objective remissions. Women with oestrogen receptor-positive tumours or tumours with unknown receptor status who received adjuvant treatment with tamoxifen experienced significantly less tumour recurrences and had a higher 10-year survival rate. The effect was greater after 5 years of adjuvant treatment compared with 1-2 years of treatment. The benefit appears to be independent of age, menopausal status, daily tamoxifen dose and additional chemotherapy.

In postmenopausal women, tamoxifen has no effect on the plasma concentrations of oestrogens but reduces the concentrations of LH-, FSH-, and prolactin, however within the normal range. Additionally tamoxifen has been reported to lead to maintenance of bone mineral density in postmenopausal women.

In premenopausal women, tamoxifen can increase the concentrations of oestrogens and prostagens but they will return to predose levels after discontinuation of the treatment.

In the clinical situation, it is recognised that tamoxifen leads to reduction in levels of blood total cholesterol and low density lipoproteins in postmenopausal women of the order of 10 - 20%. Tamoxifen increases steroid- and thyroxine-binding proteins and can thus affect the concentrations of cortisol and thyroid hormones. Additionally, tamoxifen reduces the plasma concentrations of antithrombin III

CYP2D6 polymorphism status may be associated with variability in clinical response to tamoxifen. The poor metaboliser status may be associated with reduced response. The consequences of the findings for the treatment of CYP2D6 poor metabolisers have not been fully elucidated (see sections 4.4, 4.5 and 5.2).

CYP2D6 genotype

Available clinical data suggest that patients, who are homozygote for non-functional CYP2D6 alleles, may experience reduced effect of tamoxifen in the treatment of breast cancer.

The available studies have mainly been performed in postmenopausal women (see sections 4.4 and 5.2).

Absorption:

After oral administration tamoxifen is well-absorbed achieving maximum serum concentrations within 4 - 7 hours and is extensively metabolised.

Distribution:

Tamoxifen concentrations have been observed in lung, liver, adrenals, kidney, pancreas, uterus and mammary tissues.

Metabolism:

Tamoxifen is highly protein bound to serum albumin (>99%). Metabolism is by hydroxylation, demethylation and conjugation, giving rise to several metabolites which have a similar pharmacological profile to the parent compound and thus contribute to the therapeutic effect. After four weeks of daily therapy, it was observed that steady state serum levels were achieved and an elimination half-life of seven days was calculated whereas that for N-desmethyltamoxifen, the principal circulating metabolite, is 14 days.

Excretion:

Elimination occurs, chiefly as conjugates with practically no unchanged drug, principally through the faeces and to a lesser extent through the kidneys.

Tamoxifen is metabolised mainly via CYP3A4 to N-desmethyl-tamoxifen, which is further metabolised by CYP2D6 to another active metabolite endoxifen. In patients who lack the enzyme CYP2D6 endoxifen concentrations are approximately 75% lower than in patients with normal CYP2D6 activity. Administration of strong CYP2D6 inhibitors reduces endoxifen circulating levels to a similar extent.

Although reproductive toxicology studies in rats, rabbits and monkeys have shown no teratogenic potential, tamoxifen was associated in rodent models of foetal reproductive tract development with changes similar to those caused by estradiol, ethynylestradiol, clomifene and diethylstilbestrol (DES). The clinical relevance of these changes is unknown. However some of them, especially vaginal adenosis, are similar to those seen in young women who were exposed to DES in utero (see section 4.6).

Tamoxifen was not mutagenic in a range if in vitro and in vivo mutagenicity tests. Investigations in different in vivo and in vitro systems have shown that tamoxifen has a genotoxic potential following hepatic activation. Gonadal tumours in mice and liver tumours in rats receiving tamoxifen have been reported in long-term studies. The clinical relevance of these findings has not been established.

Ethanol

Glycerol (E422)

Propylene glycol (E1520)

Sorbitol liquid (non-crystallising) (E420)

Natural aniseed flavouring A05 (flavouring preparations, isopropyl alcohol, water)

Liquorice flavouring L03 (flavouring preparations, natural flavouring substances, artificial flavouring substances, propylene glycol (E1520), isopropyl alcohol)

Purified water

Not applicable

Shelf life of the medicinal product as packaged for sale: 2 years

Shelf life after first opening the container: 3 months

Do not store above 25°C. Do not refrigerate or freeze.Store in the original package in order to protect from light.

Not all pack sizes may be marketed.

No special requirements.

Rosemont Pharmaceuticals Ltd

Rosemont House

Yorkdale Industrial Park

Braithwaite Street

Leeds

LS11 9XE

UK

PL 00427/0121

Date of first authorisation: 16 August 1999

Date of last renewal: 5 December 2008

04 February 2011