The popular ED drug Cialis has a generic equivalent called Vidalista 20 mg. It has 20 milligrammes of Tadalafil, a PDE5 inhibitor that helps men achieve an erection by relaxing the blood vessels in the penis and boosting blood flow. Because of its long-lasting effects, which can last up to 36 hours, Vidalista 20 is sometimes referred to as "The Weekend Pill."