Bioavailability of Methamphetamine

[Chip (OP)]

Bioavailability of methamphetamine is as follows:

62.7% oral; 79% nasal; 90.3% smoked; 99% rectally; 100 % IV.

sourced from drugs-forum.com

[Guts]

Taken orally, does meth work kinda like h? Does it lose the methyl group and become regular amphetamine?

[Narkotikon]

I'm gonna say no, simply because there is pharmaceutical meth. It's called Desoxyn. It's used to treat ADHD, narcolepsy, and also for obesity I think. If it was converted back into amphetamine they'd simply use Dexedrine / dextroamphetamine.

Take that with a serious grain of salt though. I've never taken meth orally. I've only smoked glass a handful of times. I'm sure our resident meth expert will chime in with a definitive answer.

[Guts]

They made pharmaceutical oral heroin at one point too... the higher lipid solubility allows it a higher BA even though its converted back to morphine. I'll wait on out expert though

[Reezy]

Following oral administration, methamphetamine is well-absorbed into the bloodstream, with peak plasma methamphetamine concentrations achieved in approximately 3.13–6.3 hours post ingestion.[102] Methamphetamine is also well absorbed following inhalation and following intranasal administration.[9] Due to the high lipophilicity of methamphetamine, it can readily move through the blood–brain barrier faster than other stimulants, where it is more resistant to degradation by monoamine oxidase.[9][102] The amphetamine metabolite peaks at 10–24 hours.[9] It is excreted by the kidneys, with the rate of excretion into the urine heavily influenced by urinary pH.[20][102] When taken orally, 30–54% of the dose is excreted in urine as methamphetamine and 10–23% as amphetamine.[102] Following IV doses, about 45% is excreted as methamphetamine and 7% as amphetamine.[102] The half-life of methamphetamine is variable with a mean value of between 5 and 12 hours.[9][102]

CYP2D6, dopamine β-hydroxylase, flavin-containing monooxygenase, butyrate-CoA ligase, and glycine N-acyltransferase are the enzymes known to metabolize methamphetamine or its metabolites in humans.[4][5][6][7][103] The primary metabolites are amphetamine and 4-hydroxymethamphetamine; other minor metabolites include: 4-hydroxyamphetamine, 4-hydroxynorephedrine, 4-hydroxyphenylacetone, benzoic acid, hippuric acid, norephedrine, and phenylacetone, the metabolites of amphetamine.[3][102][104][105] Among these metabolites, the active sympathomimetics are amphetamine, 4‑hydroxyamphetamine,[106] 4‑hydroxynorephedrine,[107] 4-hydroxymethamphetamine,[102] and norephedrine.[108]

The main metabolic pathways involve aromatic para-hydroxylation, aliphatic alpha- and beta-hydroxylation, N-oxidation, N-dealkylation, and deamination.[3][102][104] The known metabolic pathways include:[3][102][105]

So no, not like H to M. but amphetamine is a metabolite though it seems.