Pharmacokinetics cannabis

Route of administration alters the effectiveness of cannabinoids. Orally administered THC has a slower and more erratic absorption. THC was found to be 45 times more effective for analgesia after intravenous than after subcutaneous administration (Martin 1985). The pharmacokinetics of different chemical constituents of cannabis vary (Consroe et al. 1991). The elimination half-life of cannabidiol is estimated to be about 2-5 days, with no differences between genders. Comparably, the elimination half-life of Al-THC is approximately 4 days, and may be prolonged in chronic users (Johansson et al. 1988, 1989). 

Cannabis in the New World Committee Reports on Marijuana Epidemiology Methods of Use Active Ingredients Pharmacokinetics Absorption... 

Due to the chemical complexity of cannabis plant material as compared to synthetic THC, cannabis extracts are being explored as therapeutic medications. One reproducible extract of the Cannabis sativa plant contains approximately equal amounts of THC and CBD (see Pharmacokinetics of Cannabidiol, Sect. 3). The efficacy of cannabis extracts has been evaluated in clinical trials for analgesia (Holdcroft 1984 Vaughan and Christie 1984), spasticity, and other indications in affected patients (Zajicek et al. 2003). Cannabis extracts can be administered sublingually to avoid first-pass metabolism by the fiver. 

Gross SJ, Worthy TE, Nerder L, Zimmermann EG, Soares JR, Lomax P (1985) Detection of recent cannabis use by saliva delta-9-THC radioimmunoassay. J Anal Toxicol 9 1-5 Grotenhermen F (2003) Pharmacokinetics and pharmacodynamics of cannabinoids. Clin... 

Guy GW, Robson PJ (2004a) A phase 1, double blind, three-way crossover study to assess the pharmacokinetic profile of cannabis based medicine extract (CBME) administered sublingually in variant cannabinoid ratios in normal healthy male volunteers (GWPK0215). J Cannabis Ther 3 121-152... 

The pharmacokinetics of irinotecan are not altered by a herbal tea containing cannabis . 

Engels FK, de Jong FA, Sparreboom A, Mathot RA, Loos WJ, Kitzen JJEM, de Bruijn P, Ver-weij J, Mathijssen RHJ. Medicinal cannabis does not influence the clinical pharmacokinetics of irinotecan and docetaxel. Oncologist 2001) 12,291-300. 

In 9 HIV-positive patients on a stable regimen containing indinavir (mostly 800 mg every 8 hours), smoking a cannabis cigarette (3.95% tetrahydrocannabinol) three times a day before meals for 14 days resulted in a median 14% decrease in AUC and maximum level and a 34% decrease in minimum indinavir level. However, only the change in maximum level was statistically significant. Similarly, dronabinol 2.5 mg three times daily for 14 days had no significant effect on indinavir pharmacokinetics. ... 

Drug-drug interactions Cannabis Cannabis is commonly used by individuals taking methadone maintenance treatment. In a study of the effects of cannabis on methadone pharmacokinetics in 151 patients taking methadone maintenance, cannabis use and higher methadone doses were associated with a lower trough methadone concentration, believed to reflect rapid methadone clearance [122 ]. 

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