Maybe I'm just dense here, but would someone PLEASE explain this to me. I've never really gotten it. I'm on klonopin daily, xanax as needed.
Is the half-life the duration that the drug is working? Or the duration that it's at it's most concentrated levels? Or how long it stays in your system at all?
My xanax "works" between 2-3 hours, and my klonopin "works" all day. Does either of those have anything to do with it?

I apologize in advance for my ignorance. It was explained to me a long time ago, but I never really understood it then either. I was just afraid to ask for clarification.
Thanks,

Croix

i think a half-life is how long it takes the drug to decrease by half in your system.

Libby is correct.

half-life (hflf, häf-)
n.

1. Physics. The time required for half the nuclei in a sample of a specific isotopic species to undergo radioactive decay.
2. Biology.
      1. The time required for half the quantity of a drug or other substance deposited in a living organism to be metabolized or eliminated by normal biological processes. Also called biological half-life.
      2. The time required for the radioactivity of material taken in by a living organism to be reduced to half its initial value by a combination of biological elimination processes and radioactive decay.

Croix,
everyone is correct.  A's for everybody.  

The half life is the length of time that it takes for half the medicine to leave your system.

A good rule of thumb for total clearance from the body is to multiply the half life x 5.

Xanax:  11 hrs.     Total clearance roughly 55 hours or 2 days.

Klonopin:  30 - 40 hrs.  Total clearance roughly 175 hrs, or 7 days.

So, it's not a surprise that you find the Klonopin to be effective longer.  My impression is that when people have long term anxiety/panic problems they will often be switched from xanax to klonopin.

One other factor to consider is tolerance. The body becomes tolerant to xanax fairly quickly, which means the dose has to be increased to recieve the same effect.

I haven't taken klonopin, but I found the immediate release Xanax to be effective for about 3 - 4 hours at max.   The XR extended release tabs provide a smoother delivery and do me well for about 10 - 11 hours, though the literature says they effective for 17. 

Hope that helps.

A.M.

Yeah, a little. Is the half life rule supposed to apply to everyone, or is it a metabolism thing? Because like I said, my xanax usually only works for about 2 hours. It's just an add-on during tornado season. My klonopin (as a mood stabilizer) however "works" within 15,20 minutes ( that time frame usually attributed to xanax though, right?)
My xanax use probably won't have to be upped due to tolerance since I only take it occasionally. But I'm worried my klonopin might be eventually.

Sorry if this isn't making much sense, I took my nightly klonopin 30 min. ago and feel drunk. I'm just trying to get it all straight in my head.

Thanks in advance,
Croix

Well sure, if your metabolism is slower or faster, your clearance rate will change.  And the numbers that are given are just averages from actually a fairly small sample of people (not that many people are keen on taking radioactive drugs, even for money, and the tests are incredibly expensive).

So yes you could be a fast xanax metabolizer, or, my bet, you have probably a bit of tolerance and may need to use a larger dose or take the next dose sooner ---"Ask you doctor".

My impression is that more people here complain about xanax losing effect than klonopin...just my impression. 

Hope that keeps you going.

A.M.

p.s.  In looking at the xanax PI sheet I noticed that it says the typical dose for anxiety is 4 - 6mg.  Wow.  1mg does me pretty good; 4mg would lay me out on the floor.  I guess I'm an amateur worrier.

Thanks AM. Just what I was looking for.
My xanax doesn't need to be upped I think because I only need it to work for a short time. Specific phobia. I take .5mg when I need it to last for about 2 hours. If I need it to last longer (depending on when the tornado watch is scheduled to expire) then I just take another .5mg dose.

I hope that made sense.

Taking 1mg makes me too sleepy. I got a kid I need to be awake to care for. I just need it to take the edge off when I'm in panic mode. If I took 4mg, that would be the equivalent of taking a horse tranquilizer for me. I'd probably pass out within half an hour and sleep for days.

My klonopin is used mostly as a mood stabilizer and works well for such. It also keeps the general anxiety tamed.

Croix

Just to clarify this topic.

Everything stated about half life is correct, however;

Benzodiazepenes have multiple effective half lives.  One is the time it takes for the plasma concentration of the medication to reach half its original level after a single dose.  There are also metabolites produced by the medication that have various half lives (this is complex).

Another is the length of time you feel sedated by the drug.  This is the affect that tends to diminish with repeated dosing and explains why, after taking benzo x daily for a while it doesnt seem to work as well.

The final point is the length of time the drug provides an anti-anxiety affect.  This has been demonstrated by research to be quite different to the sedating half life.  It has also become clear that tolerance to this effect builds up much more slowly than to sedation.  This point is key because we often build up tolerance quickly to the sedating affect and decide to increase dosage or frequency, when the drug is still working just not making you tired anymore.

The difference betweeen sedation and anti-anxiety half lives is much greater with longer acting benzos - eg your valium sedation half life might be 4 hrs, anti-anxiety half life 8 hrs and plasma concentration half life as much as 50-100 hrs.  So there is a very long period of time where the drug is still being metabolised by your body but is having little or no effect from an efficacy point of view.  During this period it is important to remember that some of the side effects such as motor skill impairment may still be prominent.

CM, Help.

I switched from 2 mg Ativan 1 3x day, 2 at bedtime, total 10 mg. per day. The two at bedtime did the job for sedation and thus sleep, however, the anti-anxiety efficacy during the day was shit and I was taking more than prescribed.

Switched to Klonopin, 2 mg, 3x per day. Anxiety is in check, but I have NO sedation whatsoever during the day or, more importantly, at bedtime.  In fact, my anxiety starts to ramp up again in the evening around 8:00 or 9:00 p.m., as I start getting worried how long it will be before I can sleep.

I see pdoc this Saturday, and will discuss it with him, but what is your opinion? I have an addictive personality, which is why Klonopin DOES work so much better. The administration of the medication throughout my system I can't even feel. I just *don't* feel anxious. So I guess what we're talking about is a potential sleep aid, which just gives me a blah feeling, like, here we go another potential addiction. I'm comfortable with habituation for some reason, but feeling fiendish trips my red flag, and that's how I was on Ativan. (and Ritalin, a whole nother story, I don't take it anymore).

I take 60 mgs. of Cymbalta for MDD.

Any thoughts on the sleep thing?

Thanks!
S9

If you have an addictive personality and are finding tolerance building fast to drugs like xanax and atvian. you face the risk of becoming more habitual and increasingly tolerant due to the multi-day dosing.

You would almost certainly be better off on a higher dose of a longer acting drug, preferably to be used once or twice per day, or even better less often.  So the klono was proabably a good switch.

The short acting benzos are probably going to get you into trouble longer term; with the kind of doses you are talking about you will end up needing a fair hit just to avoid withdrawal, which any case would be a nightmare if you ever have to go through it.

As for other options for sleep and peace at night, there are a lot!

- an tetracyclic drug like remeron or mianeserin could help. When augmented with an ssri these drugs really knock you out if taken at night.  Low doses work well too.
- a low dose of an ap like seroquel could help as per the tetracyclic
- a sleep specific medication like ambien could be indicated

Talk to your dr about these options.  Long term, benzos arent good for sleep because you end up waking up early, and as we discussed before, build tolerance to the sedating effects.

ive been on mianserin for sleep before.  In fact I still have some.  The standard therapeutic dose is 40-60mg/day. I used to take 10mg at night and I slept like a baby and it stopped jaw clenching from the paxil.

Only issue is weight gain - 75% or so of people on remeron gain significant weight.  Mianserin is better and if only a small dose is used, it shouldnt be a major issue.

I dont use it anymore, but its good to know I have something in the med bag for sleep if I am ever desperate (as opposed to my valium, which is for anxiety).

Lastly, im not sure about cymbyalta and remeron/mianserin together.  Thats a q for your p-doc.  Its fine with ssri's. but I dont know about mixing it with MRI's, NARI's and SNRI's.

i am a little bit confused about what is being said here. i understand the distnction that CM made between sedating half-life, anti-anxiety half-life, and plasma half-life (which basically explains why xanax doesn't last for 11 hours.) but if klonopin has a half-life of 30-40 hours and we are dosing every day or even multiple times a day, isn't there a build up of klonopin in the system that we would notice eventually? or does our tolerance increase faster than this build up?

I will leave that for the scientists, all I know is Klonopin doesn't do shit to sedate me, and like the Ramones, "I WANNA be sedated," not 24 hours a day anymore, but at bedtime I want to sleep.

Thanks, CM, for your thoughtful and thorough reply. I will take it as a cheat sheet when I see Pdoc Sat.
S9

Yes, thanks for the clarification. I still find my klonopin to be sedating, that's why I take it at night. Not as a sleep aid, but I can't be dragging ass in the morning. I'm hoping the sedation wears off soon so I can start taking it in the am.

Thanks again, CM

Croix

Yes there is a little of both going on.  You are redosing while the drug is in your system, hence after a week of 3 times per day you have a higher plasma concentration than just after a single dose - when you take your dose that is.

However it works the other way too.  You can still have a reasonable plasma concentration and experience nasty withdrawal effects.  Its more the rate of reduction that the level of concentration that is important. Hence, why xanax is an absolute bitch to withdraw from, whereas valium is not so bad.

THe other consideration is, you could take a valium (or klono i particular as its stronger) tonight, and still be groggy from it the next day (more typical for casual users).

SSRI's are just the same.  Think of prozac.  Its half life is one week or something, but its taken daily. 

Id say with a balanced view you build tolerance to regular dosing and the half lives (all of them) gradually decrease over time. THe listed half lives are for a person taking a single dose with no tolerance.