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  • BDD Moderators: Keif’ Richards

how the fuck can half life change with roa?

Karamazov

Karamazov

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Jul 28, 2019
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The only cosmos in town
they say for bupe as well as other drugs, the half life is shorter for IV and much longer for sublingual. But once the drug is in your bloodstream, how does your liver know if you shot it or ate it?
 
ghostandthedarknes said:
i would guess because when you iv, it's in your blood all at once. There is no building up to peak.....
Click to expand...

This was always my understanding. It isn't that your liver is "deciding" in some way. I believe it is more that your liver, if applicable, is processing the substance as it goes through the hepatic processes. It is just getting more at once, as more is travelling through the portal at one time, as more is in the blood at one time.

Does that make sense?
 
But for meth the half life doesn't change, IIRC? It's actually longer? About 12 hours.

Why is that?

www.ncbi.nlm.nih.gov

The bioavailability of intranasal and smoked methamphetamine - PubMed

Intranasal and smoked methamphetamine are well absorbed. Although intranasal or smoked routes may decrease the risk of transmission of blood-borne diseases, exposure to methamphetamine and the possibility of drug-related complications remain substantial.
www.ncbi.nlm.nih.gov www.ncbi.nlm.nih.gov
 
That part makes sense, Kief, but then that would apply only up until the drug is absorbed. But many half lives need to pass before a drug is eliminated. So, for bupe, the half life is something like 36 hours sublingual and 8 hours IV. Say you have two people, one who shoots 2mg and another who puts 2mg under his tongue. A day or two later, when presumably all the drug is absorbed, how does the shooter’s liver know to keep the pace of halving every 8 hours and the others guy‘s liver know to keep a pace of every 36?

or is 8 hours the real half life? Once the drug is fully absorbed by whatever roa is this the true pace of elimination?
 
Wow we are getting pretty deep here. It was always my understanding that half-life was a measure of a drug's elimination at the moment of administration.

I'm just now having an epiphany that this might not be correct. Is it measures from the moment a drug enters the plasma?

This would still mean a variable rate of absorption no matter how you administer the drug.
 
It’s deep but you seem to be looking for a deeper answer.

Half-life

Half-life (t½) is the time required to change the amount of a drug in the body by one-half during elimination. The two main factors which affect drug half-life are volume of distribution and clearance; the formula for half-life is (t½ = 0.693 × Vd /CL). The 0.693 factor is in fact the logarithm...
derangedphysiology.com derangedphysiology.com
 
Yes. It stands to reason that if a drug is IVd, therefore bypassing first pass metabolism in the liver, then the half life will be shorter. But as PrincessDiz sez, we are all different. Half lifes are just an average - as are LD50s. Some people get away with it, some do not.
 
With most drugs the half life is only effected as much as the difference between the max concentration peaks. When you take a drug orally, some of that drug is still going to be going from stomach to the blood, even after blood levels have peaked there is still drug within the stomach that has yet to metabolize. When you IV something it all starts metabolizing at once, at the fastest pace the liver can.

As far as buprenorphine, it will metabolize into nor buprenorphine in larger amounts taken orally so that could account for longer half life I suppose
 
I have needles but haven't tried them yet. One day ;)

Methamphetamine is interesting for me. Vaporized it lasts longer than other MOAs. I mean, intranasal lasts about 45 minutes then I need more to keep it going

On the other hand, I've had better luck with MDA intranasal and even rectally than orally. MDMA always works better rectally too. It probably lasts an hour longer that way

Opiates work better and last way longer rectally, even meperidine
 
I think the answer is pretty simple honestly. Oral ROA takes much longer to even get to the liver, which in part is why the come up and peak levels take a few hours usually.

Verses direct IV is an instant injection where max plasma levels are acquired in less than a minute - 10 minutes maximum.

Idk it makes sense to me iv half life is shorter than oral at least. Idk how smoking plays into the picture or how dose and drugs stay in ones system.
 
Can anyone identify why meth's IV half life is longer than most other ROAs??

Gormur said:
Methamphetamine is interesting for me. Vaporized it lasts longer than other MOAs. I mean, intranasal lasts about 45 minutes then I need more to keep it going
Click to expand...

I know - i'm not leaving this thread until someone explains this to me. Lol.
 
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