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Dose-splitting for interdose withdrawal from short half-life drugs


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Also see:  doses-twice-a-day


Some members experience interdose withdrawal because of the half life of their drug.  This can happen if the half life of the drug is less than 24 hours.


Some members may experience interdose withdrawal if the half life of their drug is about 24 hours and they are a fast metaboliser.


Sometimes interdose withdrawal can occur when the member has to change from extended release to immediate release to get the doses they require.


Another situation when interdose withdrawal needs to be considered is when extended release tablets are compounded.  Even with a slow release formula added when the tablets are compounded, the shorter half life may cause interdose withdrawal.


Some members might experience interdose withdrawal when they get to a low dose of a drug.


If you suspect that you are getting interdose withdrawal the first thing to do is to do a search on the internet to try to find out the half life of the drug you are taking.  If you can't find this information check the Tips for Tapering topic for your drug.  The information may be there.  If not, then ask in your Introduction topic and one of the mods or members might be able to provide the information.


The easiest way to work out if you are experiencing interdose withdrawal is to keep daily symptom notes for several days.  If you can see a daily pattern of when your withdrawal symptoms increase related to the time you take your dose then it might from the shorter half life of your drug, or you being a faster metaboliser.


This is an example of how to keep daily notes:


On 9/28/2016 at 4:49 AM, Altostrata said:




6 a.m. Woke with anxiety
8 a.m. Took 2.5mg Lexapro
10 a.m. Stomach is upset
10:30 a.m. Ate breakfast
11:35 a.m. Got a headache, lasted one hour
12:35 p.m. Ate lunch
4 p.m. Feel a bit better
5 p.m. Took 2.5mg Lexapro
6 p.m. Ate dinner
9:20 p.m. Headache
10:00 p.m. Took 50mg Seroquel
10:20 p.m. Feeling dizzy
10:30 p.m. Fell asleep
2:30 a.m. Woke, took 3mg Ambien (NOT "took 1/2 tablet Ambien")
2:45 a.m. Fell asleep
4:30 a.m. Woke but got back to sleep




Only make one change at a time.  That is, if you are splitting your dose DO NOT make a dose reduction/increase, add/stop supplement, change brand or form of drug etc at the same time you are splitting your dose.


If you want to split your dose the gentlest way to do this is to move part of your dose, usually 1/2 of the dose, by 1 hour each day.  If you feel anxious about dose splitting you could move it by 1/2 hour each day.  You will need to observe your withdrawal symptoms and especially your sleep during this time.  If you find that your sleep is starting to be affected then you could move your second dose to the previous dose time, that is back or forward 1 hour or 1/2 hour and observe for a few days or longer to see if things settle.


So if you are currently taking your drug in the morning you would move a portion later each day.  If you are currently taking your drug in the evening you would move a portion earlier each day.


To keep the drug level consist in your body, generally it would better if your dose was split into 2 equal parts and taken 12 hours apart.  However, this may not always be possible, either because you are not able to split the dose evenly (eg compounded capsule doses won't allow it) or your sleep is affected if you take the dose too close to bed time (for an activating drug). 


If you do have to split the dose into unequal amounts, I suggest that you take the smaller dose in the evening so that if you do experience any withdrawal symptoms they are more likely to be whilst you are sleeping.  However, this may not be appropriate for a sedating drug.


Please note that there are no hard and fast rules about how to do this.  This is why it is important to observe your symptoms to see how the dose splitting affects you.


Edited by ChessieCat
added link to other topic


MISSION ACCOMPLISHED:  (6 year taper)      0mg Pristiq  on 13th November 2021

ADs since ~1992:  25+ years - 1 unknown, Prozac (muscle weakness), Zoloft; citalopram (pooped out) CTed (very sick for 2.5 wks a few months after); Pristiq:  50mg 2012, 100mg beg 2013 (Serotonin Toxicity)  Tapering from Oct 2015 - 13 Nov 2021   LAST DOSE 0.0025mg

Post 0 updates start here    My tapering program     My Intro (goes to tapering graph)

 VIDEO:   Antidepressant Withdrawal Syndrome and its Management

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  • Altostrata changed the title to Dose-splitting for interdose withdrawal from short half-life drugs

Great part about realizing that whether the drug is either sedating or stimulating needs to be taken into account just as much as the half life for maximum symptomatic relief. Great post!


 Starting ds 2 (12.5 CR'S) = 25 MG PAXIL CR 1/21/15: 1 Pill + 10mg liquid (2 weeks) 2/4: 1 Pill + 9mg Lq (3 weeks) 2/25: 1 Pill + 8 mg lq (1 week) 3/4: 1 Pill + 6 mg lq (2 weeks) 3/18/15 1 Pill + 4 mg lq (2 weeks) 4/1/15 1 Pill + 3 mg lq (2 weeks) 4/14/15 1 Pill + 2 mg lq (2 weeks) 4/29/15 1Pill + 1 mg lq (16 days) 5/15/15 1 12.5 mg Pill ONLY (9 days) 5/24/15 12 mgs liquid (8 days) 6/1/15 11mg lq (12 days) 6/13/15 10 mg.  12/3/15 Drop from 8mg to 7.6 (24 days to) 12/27/15 7.2mgs 8/4/16 6.8mgs,  11/1/16 6.4mgs, 2/5/17 6 mgs  4/3/17 5.6mgs, 4/24/17 5.2mg, 6/13/17 4.8mgs, 9/20/17 4.4mgS, 11/23/17 4 mgs, 1/1/18 3.6 mgs, 2/15/18 3.2 mgs. 4/13/18 2.8mgs, 5/11/18 2.4mgs, 6/10/18 2.0 mgs, 8/4/18 1.6mgs,  9/27/18 1.2mgs, 12/24/18 0.8mg, 3/24/19 0.64 mg,(syringe change issue date?) 4/22/19 0.60 mg, 5/24/19 0.60 mg, 7/7/19 0.52 mgs, 8/4/19 0.44mgs, 11/4/19 0.36mgs, 2/1/20 0.28mgs, 3/1/20 0.24mgs (crash April 6) Compound started 6/28/21: 0.24mgs, 8/29/21: 0.22mgs, 10/31/21: 0.20mgs, 1/03/22: 0.18mgs, 3/5/22: 0.16mgs, 5/5/22: 0.14mgs.


Original Wellbutrin Dose: 6 months from 9/14 to 3/2015, 300 XL 3/15/15: Half to 150 XL ( severe symptoms started on day 12) 4/16/15: 125mg   for 20 days to: 5/6/15:   100mg  for  15 days to: 5/21/15    75mg  for  10 days to: 6/1/15:  56.25mg      13 days to: 6/13/15: 37.25mg    7 days to: 6/20/15  28.12mg   14 days to: 7/4/15  18.75mg, 7 days to: 7/11/15; RAISE BACK TO: 28.12 to 8/14/15: 18.75mg  20 days to :9/3/15 : 12.5mg, 8/4/16 9mg 1/9/17: 8.5mg 2/8/17 8mg, 3/9/17: 7.6  4/9/17  7.2  5/27/17 6.4 6/24/17 5.8, 8/1/17 5.0, 8/29/17 4.2mgs, 10/2/17 3.5mgs, 12/28/17 2.5mgs, 2/27/18 1.7mgs,  4/19/18 0.8 mgs, LAST DOSE: 6/11/18:  3 YEARS, 2 MONTHS, 27 DAYS...

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