What should I do if I forget a dose? Resources and support See the Healthy Male site for more information about erectile dysfunction and its treatment. Talk to your doctor about eating grapefruit and drinking grapefruit juice while taking this medicine. Ask your pharmacist or doctor for a copy of the manufacturer’s information for the patient. Tadalafil can be synthesized starting from D – tryptophan methyl ester and piperonal via a Pictet—Spengler reaction.Tadalafil is a medicine used to treat erectile dysfunction (ED, also called impotence) and problems with urination caused by an enlarged prostate (benign prostatic hypertrophy or BPH). It is sometimes known by its generic name tadalafil, and sometimes known by its trade name, Cialis. There are also other brands of this medicine available. Oral Tablet mg tadalafil oral tablet from $ for 30 tablets 5 mg tadalafil oral tablet from $ for 90 tablets 10 mg tadalafil oral tablet from $ for 4 tablets Tadalafil . Tadalafil (Cialis) is used to treat erectile dysfunction (ED, impotence; inability to get or keep an erection), and the symptoms of benign prostatic hyperplasia (BPH; an enlarged prostate) which include difficulty urinating (hesitation, dribbling, weak stream, and incomplete bladder emptying), painful urination, and urinary frequency and urgency in adult men.