How long does it take for Faslodex to start working?

Once Faslodex (fulvestrant) is given by intramuscular (into the muscle) injection it takes 7 days to reach peak levels. When Faslodex is at a therapeutic level it starts to treat the estrogen dependent breast cancer by blocking estrogen receptors on the breast cancer cells and also reducing the number of estrogen receptors.

Even though Faslodex has reached peak plasma levels and is blocking and reducing the number of estrogen receptors, the effect of Faslodex on your breast cancer will not be noticeable for some time.

To find out how long it will take for Faslodex to have a noticeable effect, you will need to discuss this with your cancer health care professional, who will be familiar with your clinical situation and history. They will be monitoring your treatment and will be able to discuss when you may expect to see results from Faslodex treatment.

How often is Faslodex injection given?

Faslodex is given as an injection every two weeks for the first three doses, then once a month thereafter. The half life, which is how long it takes for half of the dose to be removed from the body, is approximately 40 days so the Faslodex remains effective for a long time. This means once you are on the monthly maintenance dose the Faslodex levels remain consistently at a therapeutic level.

Bottom Line:

• Faslodex takes 7 days to reach peak plasma levels after intramuscular injection.
• The effect of Faslodex on your breast cancer will not be noticeable for some time.
• To find out how long it will take for Faslodex to have a noticeable effect on your breast cancer you need to discuss this with your cancer specialist, who is familiar with your individual situation.