151 may have problems with any concentration higher than 5mg/ml. I've used 190 up to 20mg/ml with no issues. These of course are solutions. For a suspension you can use peg400, Evo, or Ora-plus. I usually just used good old Evo, heated till dissolved, and a little shake before dosing. All the above will work for 10mg/ml. Let me know if you have any other questions
Sorry brother Evo is just extra virgin olive oil. If you use 190 (Everclear) and want to flavor it, use alcohol based flavored extracts (peppermint is good) from the spice section of the grocery store. Water based flavorings like Mio can degrade it faster.