Saturday, May 07, 2005

Cialas - How it works on erectile disfunction

The BIG Discovery: cyclic guanosine monophosphate (cGMP)

Some very smart scientists discovered that cyclic guanosine monophosphate (cGMP) was the key to sustaining an erection.

They discovered that when a man gets sexually stimulated, a chain reaction occurs in the tissue of the penis that results in elevated levels of a substance called cyclic guanosine monophosphate (cGMP).

As long as there are sufficient levels of cGMP, the penis can remain erect. The more cGMP, the more robust and durable the erection.

If you inhibit the degradation of cGMP it stays around in the penis longer, producing a more durable erection.

Another way you can think of Cialas (and all other similar medicines) is that it preserves the elevated levels of cGMP that are created when a man is sexually stimulated for a stronger, more lasting erection.

That's how Cialas works - Cialas blocks the enzyme phosphodiesterase-5 (PDE5) which is responsible for the neutralization of cGMP. Cialas (tadalafil) is a highly selective inhibitor of PDE5. (PDE5 is not the only phosphodiesterase involved in the erectile physiology but it appears to be the most important one).

The nice thing about PDE5 blockers is that they shouldn't cause erections at inappropriate times because they only block degradation of cGMP produced in reaction to sexual stimulation, such as thinking about something sexy. If you are not being sexually stimulated, there is no cGMP to protect, so the drug remains in the background.

Absorption, Onset, Bioavailability

Cialas is readily absorbed from the bloodstream. It is about 16% bioavailable. Tadalafil is about 94% bound to plasma protein. Maximum plasma concentration of Tadalafil was achieved 2 hours post dose. The Cialas label states that It can be taken from 30 minutes to 12 hours prior to sexual activity. Efficacy of tadalafil may persist up to 24 hours post-dose.

Metabolism, Half Life, Excretion

Cialas is mostly metabolized in the liver by an enzyme known as CYP3A4 and to a lesser extent CYPC2. Tadalafil breakdown products are excreted in the feces (61%) and in the urine (36%). Cialas' mean half life is 17.5 hours in healthy men.

If you are going to take any of the PDE5 inhibitors such as Cialas, it is very important that your doctor be aware if you have a liver condition (such as cirrhosis) or kidney condition ( such as if you are on dialysis) because you may need a special dosage adjustment.

Likewise, if you try to obtain Cialas on the internet, please make sure that the person authorizing your prescription knows the true status of your liver function and your kidney function.