Posted by Larry Hoover on May 27, 2003, at 15:33:42
In reply to Re: DOES anyone know the mechanism behind this?, posted by Jaynee on May 27, 2003, at 14:41:34
> It's not Claritin-D. My doc told me that Claritin does cross the brain barrier.
I'm not meaning to be contrary here, but the drug monograph for loratadine says:
"Whole body autoradiographic studies in rats and monkeys, radiolabeled tissue distribution studies in mice and rats, and in vivo radioligand studies in mice have shown that neither loratadine nor its metabolites readily cross the blood-brain barrier."
Loratidine is thought to be incapable of crossing the blood-brain barrier because it is not lipid-soluble, and has no affinity for any of the known transporters.
The tricyclic antidepressants, as a class, arose from the accidental discovery that tricyclic hayfever meds had antidepressant effects. Loratadine is classed as a tricyclic antihistamine. Without getting into a detailed analysis of the structure-activity relationship, I have no idea if there's any substantial similarity between loratadine and tricyclic antidepressants, but you're not supposed to use them together (nor with nefazodone).
Now, just what's going on with loratadine is anybody's guess. There have been reports of weird stuff going on with it (including fatal cardiac arrhythmias). The real test is, "Does it help (or not)?", which is only answerable by doing the (personal) experiment.
Lar
poster:Larry Hoover
thread:229226
URL: http://www.dr-bob.org/babble/20030525/msgs/229482.html