Go to www. CIALIS has not been administered to patients with bleeding disorders or significant active peptic ulceration. But there are limits. Beyond that amount, you will need a prescription from a licensed U. Using a stopwatch, patients recorded the time following dosing at which a successful erection was obtained.One dose of Cialis lasts longer than a dose of the well-known Viagra (sildenafil). You can take Cialis when you need it, typically 30 minutes before sex. If that doesn’t work for you, another option is taking a low-dose pill every day for ongoing erectile support. Cialis is available as a lower-cost generic.  · CIALIS® (tadalafil), an oral treatment for erectile dysfunction, is a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5). Tadalafil has the empirical formula C22H19N3O4 representing a molecular weight of The structural formula is. Roman sells the following versions of Cialis: Generic: available in tablets of 5, 10, and 20 milligrams (mg), starting from $11; Daily Generic: available in doses of and 5 mg at $8Missing: mexico.