Author Topic: Bioavailability of intranasal and smoked meth  (Read 8427 times)

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Rhodium

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Bioavailability of intranasal and smoked meth
« on: December 04, 2003, 02:52:00 AM »
The bioavailability of intranasal and smoked methamphetamine
Debra S. Harris MD, Harold Boxenbaum PhD, E. Thomas Everhart PhD, Gina Sequeira MS, John E. Mendelson MD, Reese T. Jones MD

Clinical Pharmacology & Therapeutics 74(5), 475-486 (2003)

(https://www.thevespiary.org/rhodium/Rhodium/pdf/bioavailability.intranasal.smoked.meth.pdf)
DOI:

10.1016/j.clpt.2003.08.002



Abstract

Background
Patients in harm-reduction treatment programs are switching from intravenous to other routes of methamphetamine (INN, metamfetamine) administration to avoid risks associated with needle use. Relatively little has been reported about the bioavailability of methamphetamine when smoked or used intranasally.

Methods
Eight experienced methamphetamine users were administered smoked or intranasal methamphetamine concurrently with an intravenous dose of deuterium-labeled methamphetamine. Plasma and urine concentrations were measured for calculation of bioavailability and other pharmacokinetic parameters by noncompartmental methods.

Results
Methamphetamine was well absorbed after smoking or intranasal administration, with bioavailabilities of 79% after intranasal administration and 67% of the estimated delivered dose or 37.4% of the absolute (pipe) dose after smoking. Maximum methamphetamine concentrations occurred at 2.7 and 2.5 hours after intranasal and smoked doses. The elimination half-life was similar for intravenous (11.4 hours), intranasal (10.7 hours), and smoked (10.7 hours) methamphetamine. Clearance (272 mL · h-1 · kg-1), steady-state volume of distribution (4.2 L/kg), and mean residence time (16 hours) of the intravenous dose were similar to previously reported values. Dextroamphetamine (INN, dexamfetamine) half-life (all routes) was 16.2 hours. Methamphetamine and dextroamphetamine renal clearances (all routes) were about 100 and 1100 mL · h-1 · kg-1, respectively.

Conclusions
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.

jello

  • Guest
Is the bioavailability of smoked a bit low?
« Reply #1 on: December 05, 2003, 12:24:00 AM »
I recently read a similar abstract in which the bioavailabilty of smoked meth was somewhat higher. Theoretically, smoking meth is right up there with intravenously injecting meth in terms of ease of titration and the rate of absorbtion into the bloodstream. But, I guess blowing out HUGE billowy clouds of smoke (as is customary) would certainly lower the bioavailabity quite a bit.  8)

Here's the abstract, for anyone who's interested.


Pharmacokinetics of methamphetamine self-administered to human subjects by smoking S-(+)-methamphetamine hydrochloride
CE Cook, AR Jeffcoat, JM Hill, DE Pugh, PK Patetta, BM Sadler, WR White and M Perez- Reyes

Research Triangle Institute, Research Triangle Park, NC 27709-2194.

S-(+)-methamphetamine hydrochloride ("ice") is abused by smoking (inhaling the vapors of the material). Male human volunteers inhaled the drug from a pipe heated at 300 degrees-305 degrees C for an average inhaled dose of 21.8 +/- 0.3 (SE) mg. The same volunteers were given an intravenous injection of 15.5 mg of S-(+)-methamphetamine hydrochloride. Methamphetamine and its metabolite amphetamine were analyzed in plasma, saliva, and urine by gas chromatography. The bioavailability of smoked methamphetamine was 90.3 +/- 10.4%. (Oral bioavailability calculated from this study and a previous one was 67.2 +/- 3.1%). The geometric mean plasma half-life was 11.1 hr for smoked methamphetamine and 12.2 hr for the intravenous drug. These values agreed with urinary excretion rate data. The volume of distribution in the elimination phase was 3.24 +/- 0.36 liter/kg for the smoked dose and 3.73 +/- 0.59 liter/kg for the intravenous dose. The mean residence times were 11.5 +/- 0.5 hr and 11.3 +/- 1.74 hr for the two routes. Metabolic clearance represented 58 and 55%, respectively, of the total clearance. Significant amounts of the drug (37-45% of the nominal dose) were excreted in urine as methamphetamine and lesser amounts (7% of the nominal molar dose) as amphetamine. Renal clearance was equivalent for the two routes. Methamphetamine concentrations in plasma after inhalation showed a plateau. A model involving both a fast and a slow input function fit the data from 4 of the 6 subjects and indicated a terminal elimination rate that agreed with results from model- independent pharmacokinetic calculations. The drug caused significant subjective and cardiovascular effects.(ABSTRACT TRUNCATED AT 250 WORDS)

biotechdude

  • Guest
Meth FAQ
« Reply #2 on: December 06, 2003, 09:32:00 AM »
From memory, the Renegade's Meth FAQ summarises dosage techniques and efficiencies

http://theposse.kicks-ass.net/renegade/wizz.html




Also, it is Swix's understanding that the smoke should be 'held' within to maximise diffusion-time over the gas/blood barrier in your lungs.  Exhaling early simply blows your product out before it is absorbed into your blood stream.

That said, often 'early' exhaling blows out imputities that are less hydroscopic than meth (which is very hydroscopic).  So based on the believed purity of your product - suck or blow the night away

P.S. Swix has had to hold back the laughs while 'expert' users prance around smoking product like a cigarette all night.  Wasting all the goods to the nieve 'cool-factor' of exhaling.  Swix's trusted gineau pigs don't mind as the orders keep flowing in; and they hold onto few good tokes and are right for the night...


weaz1dls

  • Guest
Pipe lore...
« Reply #3 on: December 06, 2003, 11:20:00 AM »
SWIW was told by a little fairy that if a drop of DH2O is added to the candy in the pipe and the vapor is held in the result can even push one past that "platue" or "point of saturation", when nomatter how much one smokes they fall asleep. Of course at that ponit it is usually best to get rest anyway. Smoking in this maner is equivilant to a Hot-Rail/Flaming Line. 8)


spectralshift

  • Guest
I have always thought smoking was a ...
« Reply #4 on: December 06, 2003, 12:59:00 PM »
I have always thought smoking was a catasrophic error, in the face of the vast majority, as you'll understand, of my peers both here at the hive and in real life contact that live by smoking.

On the basis that even taking methamphetamine (not a big user at all, more fond of helping fight the WOD and forum-play) is pushing my luck...there's just no desire to reach the ultimate high's of IV and smoking.

Of course I do indulge in snorting over the oral, and a smarter person I figure would stick to the oral...

Well, I'm second smartest.  :P

weaz1dls

  • Guest
Barganing and denial...
« Reply #5 on: December 07, 2003, 10:13:00 PM »

xtaldoc

  • Guest
What about degradation products?
« Reply #6 on: December 14, 2003, 09:16:00 PM »
Swix has always tried to avoid smoking product beecause in the lit it states that it melts 'with decomposition'.  Swix assumes that this means that this route would subject the user to exposure to potentially harmfull by-products.  However, I cannot point to any specifics.  Do anybees have knowledge of refs for this notion?

Rhodium

  • Guest
meth pyrolysis
« Reply #7 on: December 14, 2003, 09:49:00 PM »

Post 246428 (missing)

(Rhodium: "Smoking meth with tobacco?", Stimulants)



xtaldoc

  • Guest
Thanks for the info...
« Reply #8 on: December 14, 2003, 10:18:00 PM »
Rhodium: The information seems to corroborate what my gut told me.  I really dont like the look of some of those degradation products and the fact that these refs include tobacco in the mix doesn't seem to greatly affect the outcome.  Swix takes enough chances in life. Much thanx.

Red_Crown

  • Guest
light vacuum smoking
« Reply #9 on: April 24, 2004, 10:25:00 PM »
This may be a little overboard but it does help to reduce pyrolysis:

Seal the inlet of a non-frail pipe with a bit of aluminum foil and poke a very small hole through it. 'Smoke' as usual with an emphasis on creating the steadiest and lowest pressure that is comfortable. The result will be slightly cooler vaporization and less pyrolysis.

I couldn't find (or measure) any relevant data on lung strength and so didn't bother to look at a phase diagram for meth HCl. It seems marginally effective so don't suck yourself into a sweat.. 'Tis at least a fun experiment.

A related ploy is to seal the inlet with yer finger then suck (with mouth only this time) and heat. This will indicate the melting point slightly earlier for those who have a hard time not scorching their shit -- giving them more time to gather their wits etc..

amalgum

  • Guest
Yeah that is a little overboard hehe :-P .
« Reply #10 on: April 24, 2004, 11:25:00 PM »
Yeah that is a little overboard hehe :P .  SWIM finds himself smoking off of the dreaded foil more than glass.  He has yet to find the right glass, as most gets to hot when trying to smoke, and then stays hot even though you remove the heat, effectively scorching product.  With the foil, SWIM can remove heat and it cools almost instantly, plus it's easier to control heat input.  Result: no scorching.  Foil is bad for your health though, which sucks.

Maybe another experiment for the real chemists among us is to load some in some glass and turn on the ol' mantle, only turning the rheostat up high enough to reach vaporization temps.

On another note, SWIM has also wondered more than once about the effects aluminum oxides and aluminum itself has upon the meth while heating.

amalgum

  • Guest
Also, re-reading Rhodiums post above, it said...
« Reply #11 on: April 24, 2004, 11:31:00 PM »
Also, re-reading Rhodiums post above, it said max. concentration of smoked meth happens at about 2.7 hours or so.  SWIM definitely beleives that is true.  It seems when SWIM first starts getting high, he'll smoke some and not feel all that jacked, and smoke a couple more bowls and still not feel that jacked.  But then a few hours later, after SWIM put the bowl down and got his attention focused on something else, it always seems that SWIM starts to get really high all of a sudden, like it all comes down on him like a ton of bricks and he is jacked more than ever.  Hehe now I have the proof for those argumentive feinds. Ooops, I mean freinds hehe 8)

elfspice

  • Guest
constrained air inlets and smoking
« Reply #12 on: April 25, 2004, 03:04:00 AM »
The very best pipe i have ever used was a meershaum pipe, made from some middle eastern marine something or other, very light and heat resistant.

The thing that made that pipe so nice other than being so light that i could forget it was dangling out of my mouth, was the size of the opening all the way through the pipe, it was about 1.5mm. The result of htis is that one requires a lot more suction to get it to come through, but the smoke for some reason is cooler, and it never occurred to me until reading the idea about reducing the air flow to effectively lower the air pressure and reduce the boiling point.

This is probably not so relevant to the smoking of methamphetamine HCl, since it requires a certain amount of heat to dissociate and liberate the meth base vapour (eeuuww, just realised that smoking meth means also inhaling a small amount of tooth destroying vapourised hydrochloric acid), perhaps more of more interest to those interested in ingesting freebases via a glass-dick type of pipe.

The one thing i learned when i first got my basepipe was that you had to suck very slowly, otherwise you would end up with droplets of hot freebase etc in one's mouth.

It never quite occurred to me that i might be able to perhaps constrain the air intake of the pipe so as to increase the amount of sucking required as i have intuitively grasped that reducing the rate of air flow makes the smoke cooler, even if droplets don't get into your mouth in the vapour stream, the problem of pyrolysis raises its head, and this is a greater problem in the case of impure mixtures which may contain quite high boiling compounds such as waxes and fats and oils and tannins etc.

Certainly this would reduce the temperature required to the temperature of the dissociation of the salt, which obviously would help a lot in reducing pyrolysis.

Red_Crown

  • Guest
2.7 hours belies method of smoking..
« Reply #13 on: April 25, 2004, 03:48:00 AM »
The lungs are supposed to be pretty much THE fastest route of administration for anything -- even faster than IV (but rarely at same dose/time) because of their vast surface are and the fact that part of the blood in the lungs is just about to get pumped up to the brain... Although, I suppose  this would only speed up the onset of subjective effects, and the plasma conc. wouldn't be any different from IV..

But still, beyond that, 2.7 hours sounds like a ridiculously long time for this supposedly fast pathway of administration. 
Perhaps much of it gets trapped in mucus (the quantity and thickness of which becomes a factor) - some diffuses slightly hindered into the blood, and the rest stays in the mucus to be slowly pushed up and eventually dumped into the esophagus for the good'ol digestive route. That seems to suite 2.7 hours better.

Or is it something else? ..blood pH goes down then back up for some reason?  Any ideas?