Tamoxifen

It07:Tamoxifen

General
Systematic name	(Z)-2-[4-(1,2-Diphenylbut-1-enyl)phenoxy]-N,N-dimethylethylamine citrate
Other names	Tamoxifen
Molecular formula	C26H29NO
SMILES	CC\C(C1=CC=CC=C1)=C(/C2=CC=CC=C2)C3=CC=C(OCCN(C)C)C=C3
Molar mass	563.6
Appearance	white to off-white crystalline powder
CAS number	10540-29-1
Properties
Density & phase	{{{Density}}} g/cm³
Solubility in water	0.05 g/100 ml (25°C)
Melting point	143 - 146 K
Boiling point	{{{Bp}}} K
Acidity (pK_a)	{{{pKa}}}
Basicity (pK_b)	{{{pKb}}}
Chiral rotation [α]_D	{{{Rotation}}}°
Viscosity	{{{Viscosity}}} cP at 25°C

Overview

Tamoxifen (brand name- Nolvadex) is a hormone drug that is used to treat breast cancer. It is an anti-oestrogen drug which means it stops the effect of oestrogen on the body’s tissues. It less commonly is used for infertility problems and can stimulate ovulation. Research is being undertaken to whether Tamoxifen is successful in preventing breast cancer in high risk patients.

How it works

The mechanism is not fully understood yet, but there is knowledge of how anti-oestrogen drugs work. Most breast cancers have receptor proteins on their surface which need oestrogen to fit into them in order for the cancer to replicate. Tamoxifen is a competitive inhibitor, fitting into these receptors and therefore stopping the oestrogen from reaching the cells. This means that the replication of the cells is either slowed down hugely or stopped altogether. Tamoxifen is either used before surgery to shrink the tumour before being removed, or after surgery to stop the cancer from returning.

How it’s taken

Tamoxifen is taken in tablet form usually in 10mg strength. Typically it is taken twice daily at the same times each day. If this is unresponsive the dose is increased to 20mg twice daily. Trials are still underway researching how long Tamoxifen should be taken for. At the moment it is believed that 5 years is the right amount of time, however some people are only prescribed it for 2 years, others indefinitely.

Common side effects

Flushes and sweats these can be reduced by cutting down on tea, coffee, nicotine or alcohol. Other drugs can also be used to reduce these symptoms.

Nausea, vomiting and indigestion – these are common effects that usually go away after a few weeks, also taking the tablets with food can help.

Weight gain- this can be due to water retention.

Change in periods- they can become lighter, heavier or stop completely.

Less common side effects can be; depression, tiredness, dizziness, headaches, blood clots, visual problems, voice changes and tumour flare.