Ear drops with ketoconazole 2%, hydrocortisone acetate 1% and isopropyl alcohol AD 100 ml.

It is very difficult to find data of solubility in isopropanol for   ketoconazole. Ketocanzole appears to be soluble in ethanol 96 °. One mentions 2 g per 100 ml. For hydrocortisone acetate we find "slightly soluble"; This means 1 g soluble in 100 to 1000 ml. Here lies the solution to the poor solubility of hydrocortisone acetate in the use of hydrocortisone.

So it seems that it is perhaps appropriate   is to replace isopropanol with ethanol 96 ° (so no antiseptic solution). A switch from isopropanol to ethanol is not a drastic change as we remain in an hydrogen center.  

If it is not satisfactory, a small amount of hydroxypropyl cellulose can be added.