Posted by pinksharkmark (196.3.74.235) on July 26, 2000 at 02:48:16:
In Reply to: Why Imitrex may not work sometimes posted by Miguel on July 26, 2000 at 00:16:06:
I can't remember the exact figure from my research back in the seventies, but I believe several studies showed that only an infinitesimal fraction of the ingested LSD ever makes it as far as the brain. In fact, the highest concentration of it is found in the liver, the LOWEST concentration is found in the brain.
If I recall correctly, it is one ten thousandth, or maybe even only one hundred-thousandth of the dose that crosses the blood brain barrier. At any rate, I do remember that it is only a couple million molecules out of the standard 100 microgram dose used for clinical research at the time.
This is one of the most puzzling aspects of the drug, and suggests that perhaps rather than directly causing the psychedelic effects, LSD may instead act as a catalyst or trigger for them.
However, the fact that even this tiny amount is found in the brain tissue would seem to suggest that it can cross the blood-brain barrier, albeit inefficiently.
For more info on LSD as a 5-HT2 agonist, check the link below.
pinky