Pharmacokinetics methamphetamine

Cook, C.E., Jeffcoat, A.R., Hill, J.M. et al. Pharmacokinetics of methamphetamine self-administered to human subjects by smoking S-(+)-methamphetamine hydrochloride. Drug Metab. Dispos. 21 717, 1993. 

Pharmacokinetics Rapidly absorbed from the G1 tract. Crosses the blood-brain barrier. Metabolized in the liver to the active metabolites. Primarily excreted in urine. Half-life 17hr (amphetamine), 20 hr (methamphetamine). 

Amphetamine and methamphetamine occur as structural isomers and stereoisomers. Structural isomers are compounds with the same empirical formula but a different atomic arrangement, e.g., methamphetamine and phentermine. Stereoisomers differ in the three-dimensional arrangement of the atoms attached to at least one asymmetric carbon and are nonsuperimposable mirror images. Therefore, amphetamine and methamphetamine occur as both d- and L-isomeric forms. The two isomers together form a racemic mixture. The D-amphetamine form has significant stimulant activity, and possesses approximately three to four times the central activity of the L-form. It is also important to note that the d- and L-enantiomers may have not only different pharmacological activity but also varying pharmacokinetic characteristics. 

Schepers, R.J.F., Oyler, J.M., Joseph, R.E., Cone, E.J., Moolchan, E.T., and Huestis, M.A., Methamphetamine and amphetamine pharmacokinetics in oral fluid and plasma after controlled oral methamphetamine administration to human volunteers, Clin. Chem., 49(1), 121-132, 2003. 

Cook, C.E., Pyrolytic characteristics, pharmacokinetics, and bioavailability of smoked heroin, cocaine, phencyclidine and methamphetamine, NIDA Research Monograph 99, 6-23. DHHS Pub. No. 1990. 

Desmethylselegiline is also an irreversible inhibitor of monoamine oxidase B in humans. There is evidence that the 1-stereoisomers of 1-amphetamine and 1-methamphetamine may have some qualitatively different actions from their d-isomer counterparts, which might result in beneficial clinical effects and could complement any beneficial clinical actions of selegiline itself. Food has no effect on the pharmacokinetics of desmethylselegiline, methamphetamine, and amphetamine. At a dose of 10 mg per day, selegiline is devoid of the cheese effect that is, it does not cause hypertension when taken with tyramine-containing foods such as cheese. 

Cook, C.E. Pyrolytic characteristics, pharmacokinetics, and bioavailability of smoked heroin, cocaine, phencyclidine, and methamphetamine. In Miller, M.A., and Kozel, N.J., eds. Methamphetamine Abuse Epidemiologic Issues and Implications. National Institute on Drug Abuse Research Monograph 115. DHHS Pub. No. (ADM) 91-1896. Washington, DC Supt. of Docs., U.S. Govt. Print. Off,... 

Pharmacokinetics of methamphetamine self-administered to human subjects by smoking S-(+)-methamphetamine hydrocloride. DrugMetab Disp 21 717-723, 1993. 

Mascher HJ, Kikuta C, Millendorfer A, et al. Pharmacokinetics and bioequivalence of the main metabolites of selegiline desmethylselegiline, methamphetamine and amphetamine after oral administration of selegiline. Int J Clin Pharmacol Ther 1997 35 9-13. 

The pharmacokinetic and toxicokinetic behavior of any isomer cannot be used to predict that of any other ephedrine isomer. Methamphetamine is a prime example. The d-isomer is a potent, and quite dangerous, central nervous system (CNS) stimulant. The 1-isomer is merely a decongestant. There is a tendency in the literature, particularly in government monographs, to lump together all "ephedrine alkaloids." Doing so is both foolish and misleading, as it implies that the toxicity of all the enantiomers is equivalent, which is clearly not the case. 

Kim, I., J. M. Oyler, E. T. Moolchan, E. J. Cone, and M. A. Huestis. 2004. Urinary pharmacokinetics of methamphetamine and its metabolite, amphetamine following controlled oral administration to humans. DrugMonit. 26 664-672. 

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