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  • BDD Moderators: Keif’ Richards | negrogesic

Bioavailability/Half-life MEGA Thread

bioavailability megathread question

So I've been searching around here on bluelight for a while now and I've read over numerous bioavailability threads and I can't find anything on taking Lorazepam [ativan] sublingually, I know in most cases pills are most effective this way where onset is concerned, I know these are stupid questions and I probably know the answer [which i assume is yes] but I want some clarification and affirmation on this please.8)

Also is it the same so alprazolam [generic xanax]?
 
anyone know the BA's for heroin?


Heroin Bioavailability:
nasal: ??? (i'd guess between 50-70% )
smoked: ~47-52%
oral: ~20-30%
IV: 100%
plugged: ?? (i'd guess aroundd 75-8% )
 
I've read the sublingual Bioavailability of buprenorphine at around 30% and intranasal at around 50%. But with suboxone which contains naloxone, the naloxone has a better bioavailability intranasally and almost none sublingually.
This is where the manufacturer gets off saying this is a detterent to keep ppl from doing it this or IV route. But there is something very contradicting in thier literature. They go on to say that buprenorphine has an even higher affinity for mu receptors than naloxone and naloxone cannot reverse buprenorphine overdose (It can somewhat alleviate it in very high doses). So this being the case, how would naloxone cause withdrawl when suboxone is injected if the bup has a higher affinity than the naloxone anyway? I personally know that snorting the pills do not cause withdrawl and are at least 20% more potent than when taken sublingually. What I said above explains why. The naloxone probably decreases its effects somewhat but with the increased bioavailability of bup Intranasally, your left with an overall higher net effect of Bup. This is proved in this study below. they administered injections of pure bup and bup with nalaxone and the pure form received higher scored on the subjective opiate effect list but the combination still scored positively on the opiate effect list proving that naloxone does not cancel out bup's effects when used other than the sublingual route. It is a scare tactic. keep in mind that if one is dependent or has a tolerance to a drug higher than that of buprenorphines ceiling effect, any withdrawl felt after using suboxone is due to the buprenorphine and its high affinity, not the naloxone.

http://jpet.aspetjournals.org/cgi/content/full/303/2/695
 
What has a higher bioavailability for adderall, snorting or taking it orally? I'm talking about the IR pills btw.

I get confused with all this amphetamine talk and the salts and what I'm taking vs. street amphetamines?
 
Any ideas for Quetiapine\Seroquel nasal BA? I know this is an unusual one but i dont have many left, and oral BA is only 9% and i need them for sleep cos i ran out of benzo's .. :(
 
Question just to see if I'm understanding bioavailability and stuff. This is hypothetical: If you have 20 mgs of oxy and it has a (I'm just making this up) 50% nasal BA and 100% IV BA, then would 10 mgs IV feel like 20 mgs nasally?
 
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oxycodone's rectal BA is given in wiki as 60-87%. Anecdotally I'd say that it feels about the same as the oral BA, just with a much faster onset.
 
Rectal vs. oral methadone

I know that the oral BA of methadone is so high that it is not worth plugging, but I was wondering whether it is likely that the oral BA of methadone is higher than the rectal BA?

If the rectal BA is significantly lower than the oral BA, I will stick with oral methadone, but if it is more or less the same I will try rectal, as the onset will be shorter and peak higher, meaning I will get more of a kick.
 
Aims

Rectal administration of methadone may be an alternative to intravenous and oral dosing in cancer pain, but the bioavailability of the rectal route is not known. The aim of this study was to compare the absolute rectal bioavailability of methadone with its oral bioavailability in healthy humans.

Methods

Seven healthy subjects (six males, one female, aged 20–39 years) received 10 mg d5 -methadone-HCl rectally (5 ml in 20% glycofurol) together with either d -
methadone intravenously (5 mg) or orally (10 mg) on two separate occasions. Blood samples for the LC-MS analyses of methadone and it’s metabolite EDDP were drawn for up to 96 h. Noninvasive infrared pupillometry was peformed at the same time as blood sampling.

Results

The mean absolute rectal bioavalability of methadone was 0.76 (0.7, 0.81), compared to 0.86 (0.75, 0.97) for oral administration (mean (95% CI)). Rectal absorption of methadone was more rapid than after oral dosing with Tmax values of 1.4 (0.9, 1.8) vs. 2.8 (1.6, 4.0) h. The extent of formation of the metabolite EDDP did not differ between routes of administration. Single doses of methadone had a duration of action of at least 10 h and were well tolerated.
Click to expand...

http://paincenter.wustl.edu/c/BasicResearch/documents/BrJClinPharm2004.pdf


Report back after you do it, along with dose used, and use history with Methadone (i.e. do you take the same dose every day via PNMNGMT or MMT, etc).
 
Tchort said:
http://paincenter.wustl.edu/c/BasicResearch/documents/BrJClinPharm2004.pdf


Report back after you do it, along with dose used, and use history with Methadone (i.e. do you take the same dose every day via PNMNGMT or MMT, etc).
Click to expand...

I have been maintained on 60mg daily for quite some time now and double dose every Saturday (orally). This Saturday I will double dose (take 120mg) rectally and will report back on Saturday evening/Sunday morning. Hopefully the larger peak resulting from this method of administration should make it more euphoric than oral dosing.
 
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