Tadalafil is an oral drug used to treat male impotency. Initially developed by ICOS, a biotechnology firm and later developed and marketed by the joint venture of ICOS Corporation and Eli Lilly and company, tadalafil got the brand name of CIALIS. Eli Lilly purchased ICOS Corporation in 2006 for $2.1 billion and took full control of the company and also the drug. Cialis was the third in the series of male impotency drugs after Sildenafil (Viagra) and Vardenafil (levitra) and was given approval by US drug and food administration in 2003. It is known as the weekend pill due to its 36 hour activity after administration which is much higher than that of the other two (upto 4 hours). As is the case with Viagra and levitra, it is advised to take only one pill per day. Tadalafil is also being tested presently for treatment of pulmonary arterial hypertension.



The empirical formula for Tadalafil is C22H19N3O4. Cialis tablets are yellow in color, film-coated, and almond-shaped. They are available in dosages of 5, 10 and 20 mgs. Viagra, Levitra and Cialis are all phosphodiesterase type 5 (PDE5) inhibitors, but Cialis is different from others in its pharmacologic feature of a longer half-life of 17.5 hours from that of 4-5 hours for Viagra and Levitra. This contrasting feature of a longer half-life results in longer duration of erections (36 hours). This is why Cialis is known as the weekend pill. This longer duration is the basis for investigation of tadalafil's use in pulmonary arterial hypertension as a once-daily therapy.

Erectile dysfunction is mainly caused due to the decrease of blood flow into the penis. As sexual tension is created, Nitric oxide (NO) is released which leads to production of cyclic guanosine monophosphate (cGMP) in smooth muscle cells and this increases the flow of blood into the corpora cavernosa. The presence of Phosphodiesterase type 5 (PDE5) lowers the cGMP and therefore the inhibitors of PDE 5 enhance erectile function by increasing the production of cGMP. Cialis can only function with the initial step of sexual stimulation, because for Cialis to have an affect, NO and cGMP production should be there and they need sexual desire. A 20 mg of Cialis is equivalent to 100 mg of Viagra. The starting dosage of Cialis is 10 mg for most of them and it is further increased to 20 mg or decreased to 5 mg depending on the results, tolerability and effectiveness

Tadalafil is presently investigated for the treatment of pulmonary arterial hypertension. Patients having it have an imbalance of PDE5/NO levels in the pulmonary vasculature. Ongoing investigations assume that PDE5 inhibition might lead to pulmonary artery vasodilation, which lowers pulmonary artery pressure and also pulmonary vascular resistance. Thus it may reduce the pressure on the right ventricle of the heart since pulmonary arterial hypertension leads to right heart failure.

Doctors need to be careful while prescribing Cialis to patients because there are some side effects and contra indications for Cialis. Patients having past history of Heart diseases might be on nitrate medications and Cialis counter reacts with them. Men with diabetes need to be careful. Cialis may cause hypotension.

One can buy Cialis directly from drug stores or buy them online through different offers. Sellers offer different discount rates to woo customers from across the world.