how to transition from xtandi to Apalutamide?

[podsart]

A change is suggested by Dr. However, Since Xtandi has a 1/2 life about 6 days, from the day you stop the amount of Xtandi starts decaying. So, Apalutamide has a half life of about 3 days, but has a fast absorption rate. This means , if you stop xtandi on day 1 and start Apalutamide on day 2, there is a period where both meds overlap in your system.

you could wait, 3-4 half life’s of xtandi for example. So, I think then you have a decay 1/2x1/2=1/4x1/2=1/8x1/2=1/16th in your body left on average, and so on. So, in this case, you have waited 3x6=18 days on avg, before starting Apalutamide. This would be a drug interaction safety approach.

on the other side of this balance beam , is your Pca safety. Assume the drug switch is due to sense that xtandi is failing to some extent. If you take a wait 3 or 4 xtandi 1/2 lives to take Apalutamide, there may be a risk that your shield against your Pca is being lowered to some extent , presumably giving your Pca a new defense hole to come through, thereby increasing danger in the cancer risk side.

So how do you find the optimal transition timing?

[tarhoosier]

what does tour doctor say?

[cesces]

You would think your doc would give good instructions. But this is the very type of thing they do poorly at.

[podsart in reply to cesces]

thanks,sometimes true

[Tall_Allen]

You are transitioning because Xtandi is no longer working for you, so what does it matter if both drugs are in your system temporarily? Erleada has greater AR affinity, so it hopefully will replace Xtandi at binding sites. If the concern is toxicity, monitor liver enzymes .

[podsart]

Thanks, didnt know Erleada has greater AR affinity. Would be helpful when I talk to doc if can you direct me to the source doc re this affinity difference. Do you know if Daralutimide is even greater in its AR affinity?