Anyone takes lower dose of xtandi and still effective ?

[Tinkudi]

Dad , 83 , has started on 80 mg of xtandi recently. Seems to be tolerating it ok , except some tiredness.

i had showed two doctors - one said to do 80 mg for a month or two and then we will take a call if to increase it . The other doctor said to scale up to 160 mg soon.

Has anyone here being taken xtandi at a lower than full dose and it is still effective ?

[Justfor_]

Define "effective". If you place trust on the SoC cookbook, "effectiveness" is synonymous to 160 mg and nothing else. User Stoneartist has been adjusting his dose in accordance to his PSA (I am doing the same with Bicalutamide). Finally, it boils down to whom you trust.

[Tinkudi in reply to Justfor_]

Hi again bica man 😊!,

Any pointers how to decide if dose is effective ?

[Justfor_ in reply to Tinkudi]

If the PSA trend is negative (declining) I call it effective.

[Tinkudi in reply to Justfor_]

Does it have to reach a certain level of psa or just a declining psa is good

[Justfor_ in reply to Tinkudi]

Ultimately, a constant decline will end up to lower then the min measurable value of the analyzer used. But you don't need to reach this point. Trending down is good enough.

[Tinkudi in reply to Justfor_]

How many days after starting it is a good time to check that

[Justfor_ in reply to Tinkudi]

No magic numbers from me, sorry. You will have to understand the mechanism and decide for yourself. The published half-life of xtandi for the "average" patient is 5.8 days, but it grossely varies from 2.8 to 10.2 days. lets asume that your dad is the "average" patient and has been on 80 mg for some days. After 10 days he will have achieved the steady state drug concentration as if he had been on 56 mg xtandi for some months now. At 20 days it will be like 72 mg, equally for 30 days -> 78 mg, 40 days -> 79 mg and finally 50 days -> 80 mg. So, if you are impatient (and I know that you are!) you can get a glimpse of any positive light in 10 or 20 days, but you stay the course, i.e. you don't adjust the dosage yet. To be absotely certain fefore deciding, you will have to check his PSA at the 2 months mark, when, even if your dad's half life is 10.2 days, the concentration will be close to 79 mg.

[Tinkudi in reply to Justfor_]

Thank you very much. 🤗

[Stoneartist]

I have the fortunate situation that my PSA decline is predictable with some accuracy - will make a new post later today. Using this predictable downward curve I tested Xtandi at 160, 120 and 80 - and found absolutely no difference. Most doctors put you on 160 because its the standard - but they readily decrease the dosage if the side effects are too much. But the clinical trails didnt do a lot of dosage testing - and the 160mg standard was chosen as the highest dose before more serious side effects start to show. I am on 80mg and doing fine!!

[Tinkudi in reply to Stoneartist]

Thanks. 😊. Looking forward to your post later today

[Rocketman1960 in reply to Stoneartist]

I rode the Xtandi horse for 66 months at 80mg.

[Tinkudi in reply to Rocketman1960]

Why half dose ?

[Rocketman1960 in reply to Tinkudi]

The first 2 weeks at 160mg turned me into an invalid. I am a great believer in lowest effective dose when it comes to meds. Early on Xtandi was given at the Phase trail dose of 160mg. It didn't take long for the powers to be to figure out that dose was a sledge hammer where a finishing hammer would do.

[Tinkudi in reply to Stoneartist]

Waiting for your post on xtandi 😊.

[Fiddler2004]

Yes, 80 mg here after starting at 160. Year 4 at 80mg 🙏 I'll post the dosage link from Xtandi soon. Best to you and your Dad.

[Tinkudi in reply to Fiddler2004]

Thanks. Was 160 tough on side effects ?

[Fiddler2004 in reply to Tinkudi]

Yes, very rough at 160mg. I remember specifically both feet and ankles swelled (huge) and painful, extreme fatigue and systemic pain. Doc was about to switch meds until I sent her here -> chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/astellas.us/docs/us/12A005-... (dosage modification information from Xtandi for either 120 or 80, I'm at 80mg, year 5, along with Lupron ,PSA currently rising ever so slowly, but still working, Xtandi in particular helps control the pain. )

[Fiddler2004 in reply to Fiddler2004]

It good medicine for me, hope it works out for you.

[Tinkudi in reply to Fiddler2004]

Thanks and wish you many more good years 😊

[Fiddler2004 in reply to Tinkudi]

Thank you and the same for you!

[ctflatlander]

I've been on 1/2 dose 6 1/2 years, still kicking. 80 yo

[Tinkudi in reply to ctflatlander]

Hi.

A few questions pls 😊

Why did you decide on half dose of xtandi ?

Why did you elect for Orchiectomy when even without that you had good T numbers ? Are you happy with the at decision

I see you started 2000 mg metformin and then stopped it later. Why was this ? We’re you taking the slow release metformin or regular one

Thanks

[EdBar]

I started at 160, used that dosage for a few years and my oncologist, Dr. Sartor lowered it to 80 due to cumulative side effects. 80 has been effective, fatigue is better but still there, it goes hand in hand with Xtandi.

Ed

[Tinkudi in reply to EdBar]

You judge efficacy based on psa numbers or also PSMA ?

[EdBar in reply to Tinkudi]

Mainly PSA, and I think scaling up from 80 to highest tolerable dose is reasonable. Especially from the start. But I’m not a doctor, but have around 10 years experience with Xtandi.

Ed

[Tinkudi in reply to EdBar]

I am sorry I did not understand - scaling up from 80 to highest tolerable dose , especially from the start.

Do you mean at the start of taking xtandi one should try to take the highest dose one can tolerate ?

[EdBar]

yes

[Tinkudi in reply to EdBar]

Why do you say that if Lower dose also proves to be effective ?

[EdBar in reply to Tinkudi]

It would likely be more effective at the higher dose.

[RCOG2000]

I had a complete response using 40 mg a day in combination with lupron for one year

[Tinkudi in reply to RCOG2000]

Did your doctor advise this ?

[RCOG2000]

complete response was defined by absence of any disease on PSmA pet ct. and undetectable psa. 8 months post treatment ultrasensitive psa remains undetectable

[MateoBeach in reply to RCOG2000]

👍🏼

[mtechguy]

I was in same situation where 160mg was too strong and reduced to 80mg with lot less tiredness and especially legs restlessness during sleep. But yesterday my MO suggested he will switch me to Apalutamide since he is not comfortable with lower dose for Xtandi