Letairis (ambrisentan) is another oral medication that can be used to treat symptoms of PH. It was FDA-approved in 2007. It works much in the same way as Tracleer does, only it is taken once a day. Also, just recently monthly bloodwork to check liver enzymes are no longer required, although some doctors may want their patients to continue to get theirs checked. Letairis can cost around $70,000 a year.