Business At $2 million, the costliest ever medicine has just got US approval Updated : May 25, 2019 02:52 PM IST Babies given Zolgensma after six months stopped losing muscle control, but the medicine can't reverse damage already done. The treatment is priced at $2.125 million. Zolgensma works by supplying a healthy copy of the faulty gene, which allows nerve cells to then start producing the needed protein.