Posted by chemist on April 26, 2004, at 13:05:57
In reply to Re: Hey Chemist - British MDs and Benzos?, posted by awatts on April 26, 2004, at 10:10:14
> > hi there awatts, can't say i am in the know as to why the brits are adverse to benzos...i will say that on this side of the pond, it does vary from doctor to doctor. the malpractice insurance cost, lousy healthcare system overall, and propensity for abuse of benzos - which rarely end in fatality, by the way - are what i perceive to be the cause. from what i have been following in the journal Nature - one of yours, and one of the best - the fright over paxil might have something to do with it, just a guess: they may be reluctant to precribe a (american version) scheduled drug (benzo) vs. a non-scheduled one (ssri or tca or maoi) for the safety issue. again, i cannot provide an explanation, but i have run into xanax-happy docs here, docs that will NOT prescribe benzos at all, and the ones in-between, who usually hit you with zolpidem (ambien stateside) and a useless and anxiety-generating ssri....sorry i cannot shed more light, and do let me know if you find an answer, all the best, chemist
> >
> I thought Xanax was a benzo. What is Xanax if not a benzo? How does it differ from benzos.
>
> awatts
>
hi awatts, xanax (alprazolam) is a triazolobenzodiazepene; the benzos lorazepam, diazepam, clonazepam are so-called 1,4-benzodiazepines (this refers to the positions of 2 notrogens found in a 7-membered ring); a benzo you might have in the uk is clobazam (brand names frisium and urbanol, if i recall), and this is a 1,5-benzodiazepene. now, you can hang various things off of the (usually) 3 rings in a typical 1,4 or 1,5 benzo, such as methyl groups, nitro groups, and halogens being popular. alprazolam is a 1,4-benzo that has an extra *ring* attached to it, as opposed to other *groups* or even atoms (H, Cl, F). this ring makes alprazolam special in that although it ``looks like'' the benzos, it is not quite, and your receptors know this very, very well. the pathway by which it is metabolised (thought i'd go with the british version, leave out the zed) is similar to the benzos, but again, not quite. the presence of that ring adds what we call hydrophobic character, which means it becomes less soluble in water and more soluble in fat. this is good news for quick onset of action, as the metabolites of alprazolam have added groups that make the metabolites more water-soluble - so they can cross the blood/brain (water/fat) barrier, and the parent compound - which is much less water-soluble - takes longer to cross the barrier but once it does, it binds very tightly (as do at lest one of the metabolites) to (at least) the GABA A-type receptor, and thus the anxiolytic effects. there are anti-depressant effects that are attributable to alprazolam, and i am uncertain as to what receptors are involved, and equally uncertain about binding affinity for serotonin, dopamine, and norepinephrine receptors, although i would think some affinity for 5-HT_{1A} and D_{2}.....all the best, hope this helps, and do let me know......chemist
poster:chemist
thread:339924
URL: http://www.dr-bob.org/babble/20040423/msgs/340217.html