First of all, it is always a good idea to provide a creditable link to back your claims, and not leave readers having to google up what you write through keywords.
The people studied by your scientists are heroin addicts, hardly any reliable population which readily hints to IV use of such benzodiazepines. If you look at the benzos they describe as the most abusable, they are all water soluble i.e they end in -pam hence they are injectable. Alprazolam is not injectable, or at least your heroin junkie would not know how to. Temazepam, for the record, is IVed and one of the only ones to produce a so called "rush" (whatever addicts may mean). Temazepam IV use is recorded to produce catastrophic consequences such as limb amputation but we know that benzos are not made to inject, right? IVed temazepam takes seconds to produce effects as opposed to aprox. one hour through oral route.
To add more insult to your arguement: temazepam, flunitrazepam and nimetazepam are HYPNOTIC benzodiazepines. That is, they are not used for anxiolisis, that is, doctors dont presribe them for daytime anxiety relief, so these benzos are, to begin with, no applicable to the argument.
Seriously, I am not trying to argue here but if you are going to try and argue my posts, provide some relevant information.
First of all, none of the benzos which you claim to be water soluble are water soluble. The only benzos which are water soluble are flurazepam, midazolam, and loprazolam (not to be confused with lorazepam), as already mentioned by another poster.
Different benzos have certain pharmacokinetic properties of absorption, distribution, elimination, and clearance that make them more apt to abuse. Temazepam, flunitrazepam, nimetazepam, diazepam (which temazepam is a metabolite of), and other benzos such as triazolam and midazolam - have these pharmacokinetic properties which make them more abuse prone.
Dark, Ross, and Hall et al also conducted research and found that different benzodiazepines have different abuse potential. The more rapid the increase in the plasma level following ingestion, the greater the intoxicating effect and the more open to abuse the drug becomes. The speed of onset of action of a particular benzodiazepine correlates well with the ‘popularity’ of that drug for abuse. Darke, Ross & Hall found that temazepam, nimetazepam, diazepam, and flunitrazepam rated significantly higher than all other benzos. The two most common reasons for this preference were that it was the ‘strongest’ and that it gave a good ‘high’.
Other studies corroborate this - like the relative toxicity studies done in Britain, Australia, Ireland, and Scandinavia - all found temazepam to be the most toxic and most sedating in overdose. The reason for this was because it was rapidly absorbed which lead to higher plasma levels, which in turn created a greater 'intoxicating' effect.
The reason temazepam is more addictive or 'more abused' has to do with it's affinity to the different GABA(A) receptor subunit subtypes (which is why it is an 'hypnotic' -
refer to this thread on benzo affinity to different GABA(A) receptors.). Along with that, temazepam has certain pharmacokinetic properties of absorption, distribution, elimination, and clearance that make it more apt to abuse compared to many other benzos.
Please refer to
this thread for more information. There are many threads on this board about the relative abuse potential for certain benzos, a simple search would've been easy. I'm not going to post these sources over and over and over again.
Overall, all you have to do is look around you and just see which benzos are most tightly regulated and placed in higher schedules because of abuse epidemics (particularly with temazepam) and ask yourself why? The studies just explain why temazepam, flunitrazepam, and nimetazepam are so popular. Diazepam also, but diazepam is overly prescribed all over the world - so that might explain diazepam's popularity.