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  • BDD Moderators: Keif’ Richards | negrogesic

Bioavailability of Methadone

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pema

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I switched from heroin to methadone. This time I had really big problems with it and was still using heroin although I drank my methadone.
So I started injecting methadone. My plan is injecting methadone for the first days and then switch to drinking and then reduce the dose.
Until now, I seems to work. This way I was able to switch to methadone without taking heroin, too. Now after some days, I think I am stable enough to switch to drinking my methadone.
But now I thought of bioavailabilty. I read a study about people smoking and injecting heroin. And withdrawal was much more severe in heroin injector than in smokers although they took same doses. This was because injected heroin had a 4 times higher bioavailability than smoked heroin.
What with methadone? In the end I will feel it by myself, if I will need more methadone when I drink it instead of injecting it. But I am looking for some medical information or clinical studies. Polamidon is not only used as a heroin substitute but also as injectable pain killer. So I think there must be information on that. But I couldn't find anything.
I even don't know if methadone/L-methadone (polamidone) has a high first-pass-effect.

Is dose increase needed when someone switches from injecting methadone to drinking methadone?
Is there a difference how long the effects will last between those two consuming methods?

Any information? Information for doctors, clinical/medical studies - That would be the best. But if there is nothing to find, maybe someone can write about his own experiences.
 
^ that's all he needs to know - oral is 84% and IV is always 100%.

There isn't really a rush with IV methadone and it won't last as long and most people feel that injecting is worthless but for some it's nearly as hard to drop the route (especially needles) as it is to drop the drug(s). Oftentimes when people switch to maintenance drugs and have trouble dropping the needle, they'll shoot saline or water to fix their need for that ritual. Usually this just helps people get over the transition.

What type of methadone are you injecting? I really hope it's not oral syrup full of sugar and additives and either way, I hope you've been filtering it properly. Some areas have few ingredients other than methadone and no coloring agents in their clinics but this is rare for maintenance preparations. Are you going to a clinic or getting it off the street? Using pills or liquid or what?
 
That's pretty high though - even IV isn't that much higher. You might need to increase your dose slightly switching from IV to oral, or you may not notice much difference.

The bioavailability megathread has a few sources - here's a paper giving the oral bioavailability as 80%.

If you're IVing pills you should always make sure you use a micron filter to prevent filler/binder particles from lodging in your lungs causing a progressive and irreversible lung disease called pneumoconiosis/talcosis.

edit: ninja'd by cane!
 
So if oral BOA is 84% and you were IV'ing, it means, in THEORY you should need a 14% increase in dose to have the same level in your blood.

However, more is at play when comparing ROAs than just bio availability...Generally speaking IV use of a substance hits faster, and wears off faster. It is also usually characterized by more intense W/D symptoms (when kicking something like IV heroin vs sniffed heroin).

With methadone, as such a long acting, high potency opioid, with little "rush" so to speak of, I am unsure of how all this will play out. Did you get that "rush" IV'ing methadone? If not it won't be much different, but if you DID, which is supposedly a rare occurrence with methadone, I wonder if you'll be able to deal without it and just the normal feel of methadone.

I also hope that CANE is correct, and that you are NOT IV'ing the shit they give out at methadone clinics. They create that solution in such a way, syrupy, sugary, etc, to make it hard, if not impossible, to IV, and definitely makes it near impossible for it to be safe, no matter how you prep it.

Also remember, quitting drugs is about more than pinching pennies to get as much as you can out of doses as possible. Its about breaking addict behaviors: such as IV drug use. Be careful OP, it seems like youre really walking a thin line between possibly quitting and falling right back down. Thats just my opinion though.
 
Now I found an interessting study by myself:
Dale O, Hoffer C, Sheffels P, Kharasch ED. Disposition of nasal, intravenous, and oral methadone in healthy volunteers. Clin Pharmacol Ther. 2002 Nov;72(5):536-45.
The interessting sentences from this abstract are:
Nasal uptake of methadone was rapid, with maximum plasma concentrations occurring within 7 minutes. The maximum effects of intravenous, nasal, and oral methadone, on the basis of dark-adapted pupil diameter, were reached in about 15 minutes, 30 minutes, and 2 hours, respectively. The respective durations were 24, 10, and 8 hours. Both nasal and oral bioavailabilities were 0.85. Subjects reported that nasal methadone caused a burning sensation.
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I find this result a little bit surprising. Intravenous methadone duration was 24 hours while oral was only 8 hours?? When I drink my methadone, it's enough to drink it 1 time per day. If the duration is only 8 hours, I would need to drink it 3 times daily. Methadone maintenance patients get their stuff only once a day (in Germany) and not 3 times a day what would be necessary when the duration really would be 8 hours. So those results look like a mistake to me.

Although I take methadone daily, I have no experience how long its effects are. I never compared the duration of injected or drunken methadone because I usually take it when I wake up. I never waited until withdrawal symptoms set in.
Has anybody experience with the duration difference of IV/oral methadone?

And what does this mean?
Both nasal and oral bioavailabilities were 0.85.
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What is a bioavailability of 0.85? Does this mean 85%?
And why is there no bioavailability given for the IV methadone? Maybe bioavailability here is 1?
 
i have sniffed methadone, and IVed it, i experienced no rush whatsoever, or even nioticed a difference in sniffing. take it oraly, for christ sake its a miracle drug with such a lng duratin and half life, and nice euphoria, be grateful for that. Remember, the faster a drug hits you, the shorter the duration and half life, so if u shoot a drug with a fast onset, it will hit u hard, if u try to IV a drug with a long half life, dont xpect a rush r nething
 
And I found another interessting study:
H. Valrie Curran, Judi Bolton, Shamil Wanigaratne, Ciaron Smyth. Additional methadone increases craving for heroin: a double-blind, placebocontrolled study of chronic opiate users receiving methadone substitution treatment. Addiction (1999) 94(5), 665-674

The interessting sentences from this abstract are:
It is well absorbed with oral bioavailability of 90% (Sawe, 1986) and peak plasma concentration being reached 2-4 hours after oral administration (Koob, 1992). Its plasma elimination half-life is 16-24 hours in opioid-naive people, but in chronic users extends to 24-48 hours) showing considerable individual variation (Tennant, 1987). This variation in how individuals metabolize thc drug may contribute to differences in withdrawal symptoms reported by patients on methadone substitution following acute daily dosage (Dyer & White, 1997).

Tolerance to the various effects of most centrally acting drugs builds up over repeated use. However, tolerance may develop at different rates to the drug's differing effects. For example, with benzodiazepines, tolerance to sedative effects develops faster than tolerance to anxiolytic or cognitive effects (Curran, 1991). Tolerance to the euphoric and analgesic effects of opioids such as methadone is thought to develop over repeated use (Gossop, 1987) but it is not clear whether tolerance also builds up to methadone's other effects. The prescribed dose is seldom escalated within treatment settings, but patients may obtain extra methadone as well as other opioids outside the treatment setting.
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The oral BA of methadone is HIGHLY variable and unpredictable. It can be anywhere from 30-90%, depending on the person and the rate of metabolism. It is well absorbed through the digestive tract but it its oral BA is very unpredictable.

Here is a paper suggesting a range of 41-90%.

The disposition of methadone was studied in eight opiate dependent subjects during detoxification. Plasma concentrations were determined by mass fragmentography for 48 hours after administration of methadone 20 mg as tablets and simultaneous intravenous injection of deuterium-labelled methadone 20 mg. Pharmacokinetic parameters were calculated for the intravenous dose assuming a two compartment open model. Bioavailability was determined by comparing the areas under the plasma concentration versus time curves of unlabelled and labelled methadone. The beta-phase plasma half-lives varied five-fold, with a range from 8.5 to 47 h. The apparent volumes of distribution varied from 2.1 to 5.61/kg. Five patients had a bioavailability exceeding 90%, and three had lower bioavailabilities of between 41 and 76%. The unlabelled and labelled drug appeared to be pharmacokinetically equivalent. The data show that for a majority of these subjects the bioavailability was higher than 45%, the previously reported value. The marked individual variation in methadone pharmacodynamics and kinetics, and the possibilities both of cellular and methabolic tolerance, require an individually optimized dosage regimen.
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u only get a fast immediate rush from IVING drugs if the drug itself has a short half-life and fast onset. other than that u wont feel an immediate rush from shooting shit like u do with coke and heroin
 
my belief is that if a drug is fast acting,and u shoot it, u will get a hell of a rush, the more long acting it is, u wont feel shit IVing it, i have IVed methadone pills, havent felt shit,..subutex is the only rush i felt when i IVed sick..
 
Old thread. Please don't revive them unless there's something of extreme importance to add.

Closed. PM me if you have questions.
 
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