Cialis (tadalafil) is a selective inhibitor of cyclic <a href="http://canadianpharmaciesshipping.com/#2451">canadian pharmacy com</a> guanosine monophosphate (cGMP)-specific phosphodiesterase type 5. Tadalafil <a href="http://storecanadianpharmacy.com/">canadian pharmacies shipping to the usa</a> has the empirical pattern C22H19N3O4 representing a molecular weight of 389.41. The structural formula is:
