Why does the half-life of a drug frequently have little correlation to how long the drug actually lasts? For instance, benzos seem to not last nearly as long as their reported half-lives, yet LSD lasts longer than the numbers I've seen for it's half-life. Can duration of effects be in any way predicted if the half-life is known, or vice versa?
Misc Correlation Between Half-life and Duration of Effects?
- Thread starter Soul137
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f33lg00d
Bluelighter
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There is a postive correlation between half-life and duration, longer half-life longer duration. But you can't go by that because metabolize of drugs vary so much. For example heroin has a short half life but lasts fairly long because it's metabolized into morphine.
I know that longer half-life = longer duration, but by how much. For instance Diclazepam. The Grand Wiki says it's half-life is 42hrs. One of the active metabolites is Delorazepam which is supposedly 80hrs. Yet Diclazepam seems to last about 24-36 hours IME, depending on dose. How is that accounted for?
Ive seen what you're talking about. Valium (diazepine) lasts a while, but not nearly as long as its half life, and it also has active metabolites with long have lives. LSD may be a catalytic action, idk. Morphine and heroin are *basically* the same molcule, the latter being acetylated and thus able to cross the BBB faster (hence a 'better' high). Tolerance and your own body chemistry play a major factor, and, with street drugs, purity no doubt plays a big role.