AdComplete the Online Consultation with our Doctor. Personalize Your Needs. If Appropriate, Get a Prescription for ED from RexMD®. Free Shipping Available.In , Pfizer scientists discovered that sildenafil, which also inhibits the PDE5 enzyme, caused penile erection in males participating in a clinical study of a heart medicine. If you are thinking about using tadalafil please discuss it with your doctor. Prolonged erections can be dangerous. Tadalafil can be synthesized starting from D – tryptophan methyl ester and piperonal via a Pictet—Spengler reaction. The FDA has also approved tadalafil for treatment of both benign prostatic hypertrophy and erectile dysfunction where the two conditions co-exist.The normal dosage of Cialis for occasional use in treating ED is 10 mg taken before sexual activity. If you have side effects with the mg dose, your doctor may prescribe a 5-mg dose. If the Viagra (sildenafil) tends to get all the attention. After all, it was the first FDA-approved oral erectile dysfunction (ED) medication, and it became a household name soon after. But its close cousin, Cialis (tadalafil), is also an effective option for many men who experience ED. Cialis is a longer-acting option that some men prefer over other ED . AdGet a Prescription for ED treatment, discreetly deliverED to your ive Offers · How It Works · Get More Info.If you take nitrates in any form, or are on treatment for pulmonary hypertension , you should not take tadalafil. One advantage Cialis has over Viagra and Levitra is its Your doctor will discuss the best treatment plan for you. Society and culture[ edit ] Marketing[ edit ] Cialis 5mg UK pack of 28 tablets In the United States, the FDA relaxed rules on prescription drug marketing in , allowing advertisements targeted directly to consumers. Subsequently, the FDA approved both vardenafil [27] and tadalafil in If you have an erection that lasts for more than 4 hours, you should go to the nearest hospital emergency department. Benign prostatic hypertrophy is a condition in which the prostate gland becomes enlarged, obstructing the free flow of urine.