psood0nym
Bluelighter
^You'll need some pH papers, which you can get cheaply and easily online, or I believe there's certain retail outlets that sell them (perhaps pool supply shops?). Simply dissolve your drug in water then dip the edge of a pH strip in and match the color to the pH chart. A neutral pH is 7. I'm not sure what the range is around 7 that's not likely to burn, but if you need to raise the pH slowly add baking soda (you're unlikely to need more than 1/5th the weight of your drug in baking soda) and if you need to lower it slowly add white vinegar or citric acid from the canning section of the grocery store (again, just drops at a time, it won't take much). You will need to heat the baking soda/drug/water solution to get the baking soda to dissolve clearly into solution. I'm not sure if there are other chemical properties of commonly used compounds other than high or low pH that could cause tissue damaging chemical burns or not, but I'd think making solutions neutral should address most issues.