Though Cialis, Viagra, and Levitra all belong to a drug class called PDE-5 inhibitors, they’re each formulated a little differently, so their effects differ somewhat. The main difference between Cialis and other PDE-5 drugs is that it has a much longer half-life. While Viagra and Levitra reach peak concentration in the bloodstream after 4 to 6 hours, Cialis levels in the bloodstream peak after 18 hours or longer. Lilly, ICOS capitalized on this difference early, pointing out that the longer half-life could allow couples to have more spontaneity in their sex lives.
You probably remember television ads for Cialis referring to it as the “Weekend Pill” due to its long half-life, and showing a middle-aged couple improbably perched on a hillside in his-and-her bathtubs watching the sunset.
Another difference between Cialis and the other PDE-5s is that Cialis also has FDA approval for treatment of benign prostatic hyperplasia (BPH), and for use as low-dose, daily therapy to treat erectile dysfunction.