I won't recommend this, but I successfully have gotten 3 mg into 1 ml of 40% EtOH followed by the addition of PG and water to have a 40% PG, 10% EtOH, and 50% water solution (which is what IV benzos, barbs, and other water insoluble drugs are prepped as for intravenous use). For other purposes, I do not like dealing with propylene glycol, so when I want an easier solvent (It takes time and some heat to use PG) I go with absolute (95% ) EtOH. It is easy to get 20mg+/ml of etizolam/clonazolam in solution so I would assume alprazolam would be similar if not slightly different. The stability of the solution with 40% EtOH is going to be different. For example, if the solution gets too cold, the alp may crash out of solution and you could end up getting nothing or swallowing 10mg worth. Higher proof alcohol will offer a more stable solution that you can use higher concentrations with. For oral dosing with liquid (not making blotter) the sweet-spot for me was 10mg per ml, with which you can use an oral syringe to measure 0.1 ml for each dose, keeping the alcohol to a minimum while making semi-large amounts (up to 100mg) easily portable. Be careful with pure powders, I had an incident where there I got residue on my hands and lost a few days because of it.
Oh, and I'm not sure if it is different where you are tricomb, but in most cases a large amount of polyethelene glycol is drank before colonoscopies. It is a water soluble polymer that functions as a non-stimulant laxative/stool softener (brand name MiraLax for home use). I can't picture drinking a whole gallon of propylene glycol... that would be awful. (just looked it up, and it would be terrible and possibly life threatening to drink an entire gallon of PROPYLENE GLycol, however POLYETHYLENE Glycol with added electrolytes is tailor made for safely clearing your digestive system out. Don't drink Prop glycol please bluelighters (in large amounts).