<prompt> TADALAFIL false is ?It is longest acting phosphodiesterase inhibitorIt cannot be used for the treatment of PAHIt is used in erectile dysfunctionIts half life is 17-5 hours  <response>: Ans. is b i.e., It cannot be used for the treatment of PAH Tadalafil is the longest acting phosphodiesterase inhibitor used for erectile dysfunction. Its half life is 17.5 hours. It can be used as once-daily phosphodiesterase type 5 PDE5 inhibitor for the treatment of pulmonary aerial hypeension PAH. 