How to prepare next Lotio: Prednisolone 0.5% Salicylic acid 4% propylene glycol 40 g Aqua AD 100 cc

Bring in a measuring cylinder 500 mg prednisolone together with 4 G salicylic acid and 40 g propylene glycol. After dissolving, dilute with water until precipitation is formed. At this moment, add the volume of antiseptic solution or isopropanol needed to fully dissolve the precipitate (e.g. 10 ml). Dilute slowly with water again and add a small amount (5 ml) of alcohol or isopropanol in precipitation. Continue in this way until the total volume of 100 ml is reached. Write down the number of ml of alcohol or isopropanol for future prescriptions with this composition!!