Propecia’s Effectiveness in Front and Sides

Just wondering if it is known why Propecia is often not effective around the front/sides ? Is there any hope for a new drug in the works that may address the front/sides?

When Propecia works, it works where the hair loss is relatively newer. The frontal area is often the first place the hair loss starts but often it is not noticed until the hairs are fully miniaturized or lost and at that point Propecia is not effective. Propecia can work well in preventing rapid hair loss in the frontal areas when the drug is started early enough. There is clearly a difference between frontal balding and crown balding, which tends to start later, in the way the genetics are expressed.