METHODS	A total of 1,112 men with a mean age of 59 years ( range 22 to 82 ) and mild to severe erectile dysfunction of various etiologies were randomized to placebo or tadalafil , taken as needed without food or alcohol restrictions , at fixed daily doses of 2.5 mg , 5 mg , 10 mg , or 20 mg up to a maximum of once daily [ DOSAGE ERROR CORRECTED ] in 5 randomized , double-blind , placebo controlled trials lasting 12 weeks .\