Hi, made the decision to formulate my own topical fin at home.
For the process I crushed my finasteride tablets (6 1mg pills), and poured into 48ml of 96% ethanol. Then mixed with a stirrer to dissolve the fin. After this I added 12ml of PG solution, to create an 80% ethanol 20% PG formulation 60ml in volume with a strength of 0.1mg per ml.
I then strained through a coffee filter to remove the fillers out of the solution, which left me with roughly 50ml of my topical fin due to some of the solution being absorbed by the coffee filter.
My question is, can I consider this final solution 50ml of 0.1mg/ml strength? I.E the ~10ml of solution that became trapped in the coffee filter contains the set concentration of finasteride? Or would it be wise to top up the 50ml with an additional 10ml of ethanol. I want to ensure that 1ml of my solution contains roughly 0.1mg of finasteride, thank you!