Can I take Cardarine (GW501516) while taking Finasteride?

You can, but it may lead to hair loss. I suggest seeing a hair loss expert now to evaluate and go over your condition and provide you information about your best treatment options. There are great non-invasive options like prp/progesterone and/or hair transplantation. See an expert. Best, Dr. Emer

From the small amount of literature,  Caradarine seems to have limited data on its effect on 5 Alpha reductase and increases angiogenesis. It would appear that there is little drug interference. Sales of Cardarine are limited in the US due to safety and purity concerns. It's hard to give a definitive answer.

Why are you taking an anabolic steroid which will accelerate hair loss that probably finasteride will only slightly moderate and you lose more hair?