Cialis (taladafil)
Tadalafil is a drug used to treat male erectile dysfunction (impotence). It was developed by the biotechnology firm ICOS and marketed worldwide by Eli Lilly and Company under the brand name Cialis.
Cialis Information
- Cialis is known as the "36 hour pill" or the "weekend pill" because unlike other similar drugs, Cialis has a long duration of action.
- Cialis blocks an enzyme that causes an erection to go flaccid. Although Cialis is similar to Levitra and Viagra, its dose, onset of action, and duration of action is unique.
- Cialis is a member of a family of drugs called PDE5 Inhibitors. Cialis is now marketed in approximately 40 countries and is available by prescription in pharmacies on five continents.
How Cialis Works
When an erection goes limp, you have PDE5 to thank. Specialized penis tissue produces a substance called cyclic guanosine monophosphate (cGMP) in response to sexual stimulation.
The more cGMP available, the more durable the erection. Cialis inhibits the PDE5 enzyme, preserving cGMP levels, therefore aiding erection viability and durability.
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 Cialis (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.
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
Cialis 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 Cialis 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.
Cialis blocks the enzyme phosphodiesterase-5 (PDE5) which is responsible for the neutralization of cGMP. Cialis (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).
Metabolism, Half Life, Excretion
Cialis 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%). Cialis' mean half life is 17.5 hours in healthy men.
If you are going to take any of the PDE5 inhibitors such as Cialis, 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 Cialis on the internet, please make sure that the person authorizing your prescription knows the true status of your liver function and your kidney function.
Take one Cialis tablet by mouth before sexual activity. In some patients, the ability to have sexual activity was improved at 30 minutes after taking Cialis. The ability to have sexual activity was improved up to 36 hours after taking Cialis. You and your doctor should consider this in deciding when you should take Cialis prior to sexual activity. Some form of sexual stimulation is needed for an erection to happen. Cialis may be taken with or without meals.
