Tadalafil is an orally administered drug used to treat male erectile dysfunction (impotence). It is marketed worldwide under the brand name Cialis.
It is a phosphodiesterase 5 (PDE5) inhibitor. Tadalafil’s distinguishing pharmacologic feature is its longer half-life (17.5 hours) compared with viagra and Levitra (4-5 hours). This longer half-life results in a longer duration of action and is in part responsible for the Cialis nickname of the “weekend pill.”
This longer half-life is also the basis of current investigation for Tadalafil’s use in pulmonary arterial hypertension as a once-daily