How long for Mirtzapine to clear system

[anxious1980]

Hi Guys

I was recently prescribed mitazapine for insomnia and anxiety caused by insomnia. However I found that upon waking I was more anxious and slept less on the mitazapine than off of it.

I was only on it for 10 nights and have ceased taking it 2 days ago - feeling far less zombified and actually slept better past 2 nights (still waking).

My question is how long will it take for my body to be clear of the Mitazapine after taking it for 10 days.

Many Thanks

---------- Post added at 19:09 ---------- Previous post was at 17:49 ----------

Anyone?

[MyNameIsTerry]

Clear elimination has the following:

HL.......%
0.........100
1.........50
2.........25
3.........12.50
4.........6.25
5.........3.13

When its under 5% its no longer clinically significant. It's more complicated than this when you consider how people taper as it will mean some overlap and then with some meds (e.g. Benzo's) you also have the storage outside of blood plasma which also needs elimination.

Factors involved in speed of distribution (drug starting to work) & elimination (clearance out of blood plasma) can be things like age (children differ, there are specific calculations for age that can be used for older people), speed of metabolism, weight (which will impact on metabolism), renal insufficiency conditions, etc. There are some very complicated guides on the internet for those interested such as some books on pharmacokinetics on Google Books but they are very difficult to understand without a medical background.

Mirt has a half life of about 20-40 hours so times that by the above. I would go with the conservative though to be sure.

[anxious1980]

Hi Terry,

Thank you for your post - could you help me a little more as I am a bit confused with it ;)

I was on 15mg for 12 nights - my last night of taking it was Tuesday 22nd September. How much would roughly be in my system now?

Thank you

[MyNameIsTerry]

No probs.

If you took it at 12am Tuesday night then you have gone 3 days (72hrs) + 10 more hours = 82hrs.

With your half life involved it would look like this:

HL.......%
0.........100
40........50
80........25
120......12.50
160......6.25
200......3.13

Thats at the longest rate of the half life, it could be less than this.

So, at 82hrs you could be at 25% but easily it could be less because if you calculated at 20hrs of half life you would have the following:

HL.......%
0.........100
20........50
40........25
60........12.50
80........6.25
100......3.13

This puts you at 6.25% which is only just above the clinically significant dose of 5%.

If you went down the middle at a 30hr half life you would get:

HL.......%
0.........100
30.......50
60.......25
90.......12.50
120......6.25
150......3.13

Which would put you close to 12.50%.

[anxious1980]

Thank you Terry - it has actually been 86 hours of not taking it. So realistically tomorrow I may not have any in my system or very minimal amounts.

I have actually felt much better in the day times not taking it - however last night when I went to bed my heart was pounding quite fast and I felt a little panicked. This morning also upon waking I felt a little anxious, thoughts going a little fast etc. Do you think this could be because the body is getting used to not having the drug in there?

I think I have to admit I may have anxiety attached to sleeping etc hence why I was put on Mirtazapine in the first place for insomnia. Driving me insane as this time 9 weeks ago - I had never even experienced anxiety. I must say though every morning I woke on the mirtazapine I felt worse as anxious and zombified was not good.

I am considering having a few drinks shortly for my birthday which is another reason I wanted to know how long it takes to clear the system.

Sorry to keep bugging you.

---------- Post added at 10:38 ---------- Previous post was at 10:36 ----------

Also when you say 25% or 12.5% does that mean 25% of 15mg is left in the system?

[MyNameIsTerry]

Yes, 25% of the full dose.

Meds reach "steady-state" by 3-5 half lives. This just means your blood plasma reflects as much going in as coming out. So, you would have achieved that with your 12 doses. Once you stop taking them the above calculations are pretty simple as you base it on your last dose only. (it's harder with tapering as there is still some going in)

The lowest half life will reflect someone with a higher metabolism just as the longer would reflect a slow one. However, there are other factors e.g. if you had renal insufficiency it would take longer. You can usually influence it by drinking more water to help flush out too. Some meds come out in higher levels in faeces too so as long as you are regular you will be efficiently getting them out.

Yes, if you have not recovered from your anxiety it will be lurking beneath so by removing more & more of the med, thats very likely to happen. It could also be some withdrawal but with being on it only 12 days that seems less likely. The guys on here will understand that more, I've never been on Mirt.

The calculation here is a standard pharmacokinetic one. Drugs differ in how fast they reach steady-state and how fast they filter out again. If you have a look at your med on Drugs.com there will be some tabs e.g. side effects, interactions, but there will also be a "professionals" tab which will explain more about this.

Some people have problems with anxiety & alcohol so if your anxiety is intensified the next day, you know you are currently one of them. It doesn't have to stay that way though, it can be because earlier on your anxiety is worse and later on things bother you less or not at all. It's very much an individual thing. Drugs.com will tell you if Mirt and alcohol have interactions, which is likely, but having said that some meds interact more with others.

[anxious1980]

Thank you for all your help Terry - have a lovely day x

[hanshan]

A simple rule of thumb is to multiply the half-life by five, so 150 - 200 hours to be clear after the last dose, based on a half-life of 30 - 40 hours. There will still be a small amount in the body but without effect.