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Why does Methadone take so long to peak ?

Because it's really lipophilic and it has really high plasma-protein binding (~80%). This means that it lags in each tissue distribution step; i.e. entering the gut wall, leaving the gut, leaving the blood, penetrating the brain.
 
Last edited:
BilZ0r said:
Because it's really lipophilic and it has really high plasma-protein binding (~80%). This means that it lags in each tissue distribution step; i.e. entering the gut wall, leaving the gut, leaving the blood, penetrating the brain.
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Really - 80%? Could you give me a reference for that because I always thought it wasn't too bound & that it was the pKa & BBB permeation that made it so slow... shows how much I know ;)
 
Why does it being lipophilic make it 'lag' in between membranes? Forgive me of any ignorance as I'm just about to start a course of pharmacology at Uni but I've noticed that chemicals with high lipid-solubility tend to be much faster at crossing the BBB and reaching peak plasma levels because of their ability to cross membranes so easily?
Could somebody explain to me why it may cling to one membrane rather than another?
Cheers =D
 
In one word: structure

Even intravenous methadone takes quite some time reach peak plasma, subjectively, about 70 minutes. The wonderful thing about this, is the amazing duration which it stays at peak plasma. Having abused virtually all clases of opioids, even rare esoteric opioids; I still rank IV methadone ampules/vials among the most favorable opioid commonly available. However, due to my propensity for opioid addiction I mujst abstain from even oral methadone, which i also enjoy. Morphine and DAM has its place, but the k-agonist properties can make the experience emotionally volitile. The last time I used IV street levek tar heroin (roughly six years ago), I wound uo crying like an infant. Methadone, in high doses, preferable. Levorphanol is also a drug that offers similarly enjoyable effects, with the added benefits of a" rush' of sorts. I have barred myself from using opioids of any potency, P.O. or I.V.

Methadone is worth the wait in regard to pharmacokinetics (of which there is huge amount of data online). If you are having issues with withdrawal, i suggest doing what I used to do when on MMT: set your alarm for 60-90 minutes before intended wake up time, take the tablets or liquid, sleep for another 60-90 miniutes, and upon waking you will" comfortable".
 
It's the biochemical makeup of your brains anatomy and also the process which facilitates the enzyme sin the gut to transform methadone into methylesylmethadone, which is the primarily psychoactive drug that crosses the blood brain barrier.

Either that, or:
You have a tolerance dope-fiend!
 
Yeah I agree with this findings.

IV methadone doesn't seem to be any better than PO methadone. If you are dope sick though, I would IV the methadone, because you will start to feel "better" faster than if you did it by PO.

However, I'm not sure I totally believe that ;)
 
Many people think there is little difference, until they try methadone that is formulated for injection. Injecting the syrup or some crude pill extraction is not only dangerous, it simply does not nearly mimic methadone formulated for intravenous use. You will only this in a hospital setting, and even the......Methadone is by far the most "controlled" of the C-II opioids (because of its very strict prescribing indications), and it is comparatively 'well-inventoried/reconciled". Health-care professionals always find ways around these things however, some of the physicians and assistants/nurses are rather clever...........
 
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