Tadalafil can be synthesized starting from D – tryptophan methyl ester and piperonal via a Pictet—Spengler reaction. In trials investigating Cialis, the majority of participants receiving the drug experienced a significant improvement in ED and maintained an erection. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. In BPH, the medication relaxes the urinary tract and bladder muscles, allowing for more effortless urine flow. Your doctor will probably tell you not to take tadalafil if you are taking nitrates. Alternatively, Cialis may be prescribed as an as-needed treatment for ED, to be taken before sexual activity. One of these is PAH.How Cialis Works. Tadalafil and other PDE5 inhibitors primarily work by inducing muscle relaxation. Tadalafil stops the breakdown of a chemical responsible for relaxing muscles. In ED and PAH, the drug targets muscle cells in blood vessels. When the blood vessel muscle cells relax, this expands the vessel and increases blood flow; this . AdGet Deals and Low Prices On pharmacy prescriptions At Amazon. We Offer an Extensive Selection Of Everything Else Store At Amazon. Order Today!Types: Pet Supplies, Beauty & Personal Care, Anxiety, Pharmacy, Medical Care and more. Side Effects. Headache, stomach upset, back pain, muscle pain, stuffy nose, flushing, or dizziness may occur. If any of these effects last or get worse, tell your doctor or pharmacist promptly. To.