Erectile Dysfunction Information
Erectile dysfunction (ED) is sexual dysfunction characterized by the inability to develop or maintain an erection of the penis during sexual performance.
A penile erection is the hydraulic effect of blood entering and being retained in sponge-like bodies within the penis. The process is often initiated as a result of sexual arousal, when signals are transmitted from the brain to nerves in the penis. Erectile dysfunction is indicated when an erection is difficult to produce. There are various circulatory causes, including alteration of the voltage-gated potassium channel, as in arsenic poisoning from drinking water. The most important organic causes are cardiovascular disease and diabetes, neurological problems (for example, trauma from prostatectomy surgery), hormonal insufficiencies (hypogonadism) and drug side effects.
Psychological impotence is where erection or penetration fails due to thoughts or feelings (psychological reasons) rather than physical impossibility; this is somewhat less frequent but often can be helped. Notably in psychological impotence, there is a strong response to placebo treatment. Erectile dysfunction, tied closely as it is about ideas of physical well being, can have severe psychological consequences.
Medication Types
Phosphodiesterase type 5 inhibitors
The cyclic nucleotide phosphodiesterases constitute a group of enzymes that catalyze the hydrolysis of the cyclic nucleotides cyclic AMP and cyclic GMP. They exist in different molecular forms and are unevenly distributed throughout the body.
One of the forms of phosphodiesterase is termed PDE5. The prescription PDE5 inhibitors sildenafil (Viagra), vardenafil (Levitra) and tadalafil (Cialis) are prescription drugs which are taken orally. They work by blocking the action of PDE5, which causes cGMP to degrade.
Alprostadil
Alprostadil in combination with the permeation enhancer DDAIP has been approved in Canada under the brand name Vitaros as a topical cream first line treatment for erectile dysfunction.
Another treatment regimen is injection therapy. One of the following drugs is injected into the penis: papaverine, phentolamine, and prostaglandin E1.
Erectile Dysfunction Medication Information
Viagra
Sildenafil citrate, sold as Viagra, Revatio and under various other trade names, is a drug used to treat erectile dysfunction and pulmonary arterial hypertension (PAH). It was originally developed by British scientists and then brought to market by the US-based pharmaceutical company Pfizer. It acts by inhibiting cGMP-specific phosphodiesterase type 5, an enzyme that delays degradation of cGMP, which regulates blood flow in the penis. Since becoming available in 1998, sildenafil has been the prime treatment for erectile dysfunction; its primary competitors on the market are tadalafil (Cialis) and vardenafil (Levitra).
Cialis
Tadalafil is a PDE5 inhibitor, currently marketed in pill form for treating erectile dysfunction (ED) under the name Cialis; and under the name Adcirca for the treatment of pulmonary arterial hypertension. It initially was developed by the biotechnology company ICOS, and then again developed and marketed world-wide by Lilly ICOS, LLC, the joint venture of ICOS Corporation and Eli Lilly and Company. Cialis tablets, in 5 mg, 10 mg, and 20 mg doses, are yellow, film-coated, and almond-shaped. The approved dose for pulmonary arterial hypertension is 40 mg (two 20-mg tablets) once daily.
