You can susped Anastrazole (Arimidex) in water because the milligram amount per serving is so damn low. Most will still use some type of grain alcohol though to dissolve it so that it is preserved and lasts longer. Now this would be for the oral version.
Next, you can make Arimidex into an injectable version probably in bacteriostatic water w/o any problems or I'm sure it would work just fine dissolved in some BA and then add your carrier oil to the mix.
I have seen sterile injectable forms of Arimidex so YES they are out there, but again with something that is so orally viable it really doesn't make too much sense to inject it, unless it is already blended in with the gear you are already injecting.