Posted by Cam W. on August 30, 2001, at 17:04:49
In reply to But are they different?, posted by Squiggles on August 30, 2001, at 15:26:45
Squiggles - Surprizingly, there is a lot of debate on this question. Some researchers say that the only difference between benzodiazepines is in their pharmacokinetics (ie. absorption, distribution, metabolism, and excretion).
A major distinguishing feature between all benzos is their fat solubility; their ability to be taken up by fat cells and the ease with which they are released. The more fat soluble benzos are released slower, thus have longer half-lives.
Also, since all benzodiazpines bind to the same area in the GABA receptor complex, it is said that they should all have the same action. The differences seen in their actions is due to the ability of certain benzos to enter areas around specific brain structures; again relating to fat solubility (related to the polarity - ionized state - of the molecule). Stimulating GABA receptor complexes (thus slowing neuronal electrical transmission via sodium influx into nerve cells) by specific benzos in specific brain structures would cause different effects between the benzodiazepines.
To complicate things (if that is possible), one must also consider metabolism. There are (at least) 3 main ways benzodiazepines are metabolized (oxidation, glucuronide conjugation, and nitro-reduction). The metabolism mainly occurs in the cytochrome-P450 system of the liver. As we age, we are less able to oxidize or nitro-reduce, but conjugation reactions seem to remain at normal levels. So, when looking for a benzo for the elderly, the route of metabolism is a concern. Lectopam™ (bromazepam); Serax™ (oxazepam); and Restoril™ (temazepam) are probably the best for the elderly.
I hope that this is not too confusing. The are other minor differences, but these are the main ones (and my wife wants to use the computer). - Cam
poster:Cam W.
thread:76985
URL: http://www.dr-bob.org/babble/20010828/msgs/76999.html