I am interested in the Biological Half Life of substances. In the previous wikipedia link, I've already found the half lives of common pharmaceutical products. I can't seem to find similar data for recreational substances, does anyone know these half lives?
Wikipedia reports biological half-lives for several recreational drugs I just tried (cocaine, THC, MDMA). In each case, I went to the page for the particular substance, and Wikipedia keeps an information box at the top of the article containing the pharmacokinetic data. THC's half-life has a citation to the scientific literature, while the other two I checked do not. I think it might be slightly harder in general to get good data for the purely recreational drugs. I would expect drugs without an accepted medical benefit to be less well-studied. To find what's there, though, it looks like you will be able to look up each active ingrediate individually. Depending on what you need, Wikipedia might be okay. If it's not, follow the Wikipedia citation back to the literature if it's there, or try PubMed.
Try DrugBank. It's a comprehensive and free-to-use database for a large number of drugs. I saw it has data on Cocaine and Heroin (look in the pharmacology section).
(Yes, this question is three and a half years old, but it still may help someone...)