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ZK2015

Tapering according to the serotonin transporter occupancy curve

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ZK2015

Hi,

 

I started this topic a while ago

 

and it has been 6 months now since my last dose of Prozac, so I'd like to share the way I used to taper so may be someone out there benefit from it, However I'd like to point out that I'm not a doctor and that this worked for me merely through trial and error, so here we go.

 

As I mentioned in my first topic my first tapering attempt was too fast that I had awful withdrawal symptoms and had to reinstate, and the 10% approach was too slow for me as I was able to make larger drops without much symptoms, I then found the following research paper here on the forums:

It's a paper on the percentage of serotonin transporter occupancy of Prozac (and other SSRIs) in the brain, in other words it basically measures the amount of serotonin receptors in the brain blocked by the medication, at 20mg most SSRIs will block 75%-85% of these receptors.

After going through the paper I found that the percentage for Prozac occupancy follows the following equation:

 

Occupancy% = 86*dose/(1.94+dose)

 

So for example, if you take 20mg Prozac, the approximate occupancy% = 86*20/(1.944+20) = 78%, and so on.

What I did next was finding the maximum percentage I can go down without suffering too much withdrawal symptoms, and with some trial and error I found this percentage to be 8%, meaning if I'm currently at 78% I can go down to 70% without much withdrawal symptoms, any higher and the symptoms are unbearable.

So I prepared a table with 8% drop downs, calculated the dosage for every percentage and stayed on every dosage from 2-4 weeks depending on the symptoms, this worked perfectly for me as I was able to calculate the next dosage that wouldn't cause much symptoms, for example I was able to drop directly from 20mg to 10 mg and from 10mg to 5mg, however as the dosage decreased the drops where slower to maintain the 8% drop, this also allowed me to know when to stop taking the medication completely, for example at 0.5mg I was still at 18% so I had to drop to as low as 0.1mg before stopping completely.

My last dose was on 17/4/2017, I had to make 14 drops over the course of a year, and although I had a couple of hiccups toward the end I was able to get through them by staying a little longer on the dosage and doing lots of exercise.

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ChessieCat

Hi ZK,

 

Thanks for posting about your tapering method.

 

It would be really great if you could post an update in your Intro topic about what symptoms, if any, and their severity since you stopped taking Prozac.

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Krasiyan

I'm guessing the forumala for Paroxetine will not be Occupancy% = 86*dose/(1.94+dose) ? This really puts me to question how I've been probably 80% + occupancy on 40 mg for years and stopped in just one months time. No wonder I'm withdrawing.

 

Even if I start 5 mg it's gonna bring the occupancy back to about 50% in a month. Thats a lot considering it's only 5 mg. And even if I stabilize on 50 % occupancy does stupid pills aren't made to be reduced by 1 mg so good luck stopping it without some kind of professional or something.

 

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Gridley

Check Brassmonkey's thread.  He reduced from 40mg Paxil cutting pills and using a Gemini 20 scale even at very low doses.

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ZK2015
20 hours ago, Krasiyan said:

I'm guessing the forumala for Paroxetine will not be Occupancy% = 86*dose/(1.94+dose) ? This really puts me to question how I've been probably 80% + occupancy on 40 mg for years and stopped in just one months time. No wonder I'm withdrawing.

 

Even if I start 5 mg it's gonna bring the occupancy back to about 50% in a month. Thats a lot considering it's only 5 mg. And even if I stabilize on 50 % occupancy does stupid pills aren't made to be reduced by 1 mg so good luck stopping it without some kind of professional or something.

 

 

Hi Krasiyan, the equation for Paroxetine will be  Occupancy% = 102*dose/(5.2+dose)

so yes at 5mg you will be at 50% occupancy, however it is really a matter of trial and error you can try different percentages till you find the one that you can tolerate and start calculating your doses based on it.

also as Gridley mentioned you can cut your pills or make liquid from them, personally I found it easier to measure doses from liquid solution.

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ZK2015
On 10/29/2017 at 12:50 AM, ChessieCat said:

Hi ZK,

 

Thanks for posting about your tapering method.

 

It would be really great if you could post an update in your Intro topic about what symptoms, if any, and their severity since you stopped taking Prozac.

 

sorry I can't edit the intro topic for some reason.

 

but anyway, my symptoms were very mild during tapering even negligible sometimes, they were mostly anxiety and depression, however the hardest part was toward the end when I stopped completely that's when I started having strong feelings of anxiety again "still bearable though", that lasted for almost 2 weeks but I guess I was waiting for some withdrawal symptom to reappear that I made myself anxious.

I felt completely back to normal about a couple of months after I stopped, and I haven't had any problems since then.

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bruno2016
57 minutes ago, ZK2015 said:

I felt completely back to normal about a couple of months after I stopped, and I haven't had any problems since then.

wow thats really awesome! Thanks for sharing with others. 

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kesh

If you invert the formula you get

 

Dose = (1.94*Occ)/(86 - Occ)

 

Where Occ is percent receptor occupancy. 

 

This means that you could plug in the occupancy taper you want and get the required dose. 

 

However, I don't think anyone knows what kind of receptor occupancy taper is best.

 

 

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RealMe
On 11/3/2017 at 9:32 AM, ZK2015 said:

 

sorry I can't edit the intro topic for some reason.

 

but anyway, my symptoms were very mild during tapering even negligible sometimes, they were mostly anxiety and depression, however the hardest part was toward the end when I stopped completely that's when I started having strong feelings of anxiety again "still bearable though", that lasted for almost 2 weeks but I guess I was waiting for some withdrawal symptom to reappear that I made myself anxious.

I felt completely back to normal about a couple of months after I stopped, and I haven't had any problems since then.

Are you still doing well?  I have started a slow taper of prozac 10, so I read your method and got a lot of hope from your experience.

 

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ZK2015
On 12/29/2017 at 11:52 PM, kesh said:

 

However, I don't think anyone knows what kind of receptor occupancy taper is best.

 

 

It's a matter of trial and error really, it took me a couple of tries till I found the highest occupancy I can taper without much problems 

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ZK2015
11 hours ago, RealMe said:

Are you still doing well?  I have started a slow taper of prozac 10, so I read your method and got a lot of hope from your experience.

 

Yes, it's been 8 months now and doing fine, Wish you luck with your taper.

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Altostrata

The fundamental problem is you do not know the exact shape of your own occupancy curve. The paper is based on an average. You cannot assume your own curve is exactly like this one, or that your own tolerance for tapering is dependent solely on receptor occupancy rates.

 

That said, ZK, I'm glad you're doing well. Please update your Intro topic.

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kesh

Yes, one thing about the original papers is how the data points of individuals' sert occupancy float quite widely around the curve.

 

And the 10mg, 20mg, 40mg typical therapeutic doses for say fluoxetine are in reality likely to have a far wider range for different people. 

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DoctorMussyWasHere
On 29/10/2017 at 12:13 AM, ZK2015 said:

Occupancy% = 86*dose/(1.94+dose)

 

Is anyone keeping a central record of the equations?

 

This one is for risperidone:

y = 90*(x/(0.8+x))

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