for the treatment of erectile dysfunction (ED) and benign prostatic hyperplasia (BPH). It is also marketed under the brand name Adcirca for the treatment of pulmonary arterial hypertension (PAH). Cialis belongs to a class of drugs known as phosphodiesterase type 5 (PDE5) inhibitors, which work by increasing blood flow to the penis and relaxing the muscles in the walls of blood vessels.

Cialis was first approved by the US Food and Drug Administration (FDA) in 2003 and has since become one of the most prescribed drugs for the treatment of ED. It is available in various dosages, including 2.5 mg, 5 mg, 10 mg, and 20 mg, and is taken orally in the form of a tablet. Its effects can last for up to 36 hours, earning it the nickname "the weekend pill."

The active ingredient in Cialis is tadalafil, a chemical compound that works by inhibiting the PDE5 enzyme. This enzyme is responsible for breaking down another compound called cyclic guanosine monophosphate (cGMP), which is involved in the relaxation of smooth muscles and the dilation of blood vessels. By inhibiting PDE5, tadalafil allows cGMP to accumulate, leading to increased blood flow to the penis and ultimately, a stronger and longer-lasting erection.
This is an essential bookguide the will enlight you more about cialis