Legal Classification of Medication
POM
Tamoxifen tablets can only be obtained in accordance with a prescription given by an appropriate practitioner and therefore the legal status of the medication is prescription only medication (POM).
Formulations
Tamoxifen is available as tablets and oral solution. The following strengths are available:
Class of drug
Tamoxifen is an oestrogen-receptor antagonist.
Indications
How does it work?
Oestrogen promotes the growth of breast cancer cells. Tamoxifen stops oestrogen from reaching cancer cells so that they grow slowly or stop growing altogether. Breast cancer cells can be either sensitive to oestrogen or progesterone. Cancer cells which are sensitive oestrogen respond well to tamoxifen.
How is it taken?
Tamoxifen should be swallowed whole with a glass of water. It is usually prescribed as a single daily dose and should be taken at the same time each day. Tamoxifen is usually prescribed for 5 years.
For the treatment of breast cancer 20mg daily is taken. Evidence has shown that higher doses give no further benefits as 20mg taken daily substantially increases survival rate in early breast cancer.
Women treated for infertility usually take20mg daily on days 2, 3, 4, and 5 of cycle. The doctor will determine the best possible dose required as it might need to be increased in some circumstances.
Pregnancy and Breast feeding
Tamoxifen should not be used in pregnancy as it can effect fetal development. Effective contraception should be used during treatment and 2 months after stopping it.
Tamoxifen can stop lactation in nursing mothers therefore it should be avoided and used only if the benefits outweigh the risks.
Contra-indications
Tamoxifen treatment should not be used in patients who have a history or are likely to develop clots in blood which travel to other parts of the body (thromboembolism)
Side-effects
The following are side-effects experienced when on tamoxifen therapy:
Tamoxifen can increase the risk of blood clot formation in a blood vessel which is carried to other parts of the body. If symptoms such as sudden breathlessness and any pain in the leg or calf muscle develop the medicine should be stopped and an emergency doctor should be contacted as soon as possible.
Patients taking tamoxifen have a slightly higher risk of cancer of the uterus. However, it must be stressed that studies have shown that the benefits of the treatments far overweigh the risks. Symptoms such as unusual vaginal discharge or pelvic pain should be reported to the doctor immediately.
