Alprazolam (xanax) Half-life Theory? Urgent

FoolsGold Says:

After much research, I understand Alprazolam's (Xanax) half life is approximately 11 hours, correct? So, as an example, if a person took a 1 mg dose of xanax, it would be down to .5 milligrams in their system after the approximate 11 hours?

I know there are a lot of other factors too, such as age, weight, metabolism, etc., but can anyone help me understand how you would figure up approximately how much would be in someone's system going by half lives and if they took multiple doses? This may sound confusing so I'll use an example.

Day 1:

2:00 P.M. - Took 1.5 mg
6:00 P.M. - Took 0.5 mg

Day 2:

7:00 A.M. - Took 1.0 mg
10:00 A.M. - Took 0.5 mg
4:00 P.M. -Took 0.5 mg
10:00 P.M. - Took 1.0 mg

Day 3:

9:00 A.M. - Took 1.5 mg
1:00 P.M. - Took 1.0 mg
5:00 P.M. - Took 0.5 mg
9:00 P.M. - Took 0.5 mg

Day 4:

8:00 A.M. - Took 1.0 mg
11:00 A.M. - Took 1.0 mg

Now, using the above amounts and half life of approximately 11 hours, how could you figure this up? Start with the 1.5 mg dose at 2:00 P.M. and then add the 0.5 mg dose at 6:00 P.M., which comes out to 2.0 mgs, and then divide that by 2 when the 11 hour half life hits at 1:00 A.M. bringing the level down to 1.0 mg. Then add day 2's, 7:00 A.M., 1 mg dose to that, bringing it up to 2.0 mgs now? And just continue like that?

Sorry if this is confusing, just really trying to understand it all, and hoping someone can help. Thanks!

2 Replies

Earliest Newest Votes
Verwon Says:

Hello, FoolsGold! How are you?

No, the flaw in your theory is that fact that you have the entire amounts adding up and being halved, when a new one is taken, that's not how it works. If it were, you'd never be able to lower a dosage of a medication.

If you took 1.5mgs at 2pm, then it will reach 50% 11 hours later, if you take another 0.5mgs at 6pm, it's going to reach its 50%, 11 hours later and so on. Since they weren't taken together, you can't add them together, then figure that the half-life 11 hours later is 1mg, it doesn't work like that.

I'm not sure if I'm being clear here, so please feel free to let me know if that is the case and I'll try to make it more clear.

But basically, to sum it up, the entire elimination time is 5 to 6 half-lives, so for Xanax, you're looking at 55 to 66 hours. Thus, if I took at 1mg dosage at 6am, by the time I hit that 55/66 hour span after taking it, that original 1mg dose is done, regardless of my having taken more at noon. That's why you can't just take a dose or 2 of a higher amount, then suddenly go lower and still get the same beneficial effects of the higher dosage, that's also why people who drop suddenly experience withdrawals.

The amounts that accrue to lengthen this process due to someone being on it continuously for a long period of time, are actually minuscule and would be undetectable.

The FDA lists this medication as carrying the risk of being habit forming and could cause side effects, such as nausea, dizziness, headache and irritability.

Is there anything else I can help with?

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kim lawson Says:

LEVELS OF XANAX. XANAX LINGERS OR a short action benzodiazepine. 4h, maybe more depending on your liver function. Fatty infiltration or a > healthy liver, like high hepatic enzymes

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