by arjay » April 26, 2010, 8:01 pm
My research indicates that essentially medications like Viagra have the effect of increasing blood flow in the body and thus to the penis:
Medications like Viagra, Cialis and Levitra - all belonging to the family of drugs termed PDE-5 inhibitors -these three drugs, known pharmacologically as Sildenafil, Tadalafil and Vardenafil respectively, all have essentially the same action within the body. Despite the reputation they have in some quarters of enhancing a man's maleness, they have nothing to do with virility or male hormones like testosterone.
By understanding what exactly erectile dysfunction is and how these medications work, it will be realised that in the vast majority of men, erection difficulty arises due to defective blood flow in the arteries supplying the penis.
When a man is sexually stimulated, a sequence of chemicals is released into his blood stream, the culmination of which is the release of a hormone called Cyclic GMP that acts to dilate the blood vessels going to his penis. When blood flow into the spongy tissues of the penis increases, the organ becomes turgid and erect. Cyclic GMP does not last long at its site of action, being destroyed by an enzyme termed PhosphoDiEsterase or PDE. If the action of this enzyme could be inhibited, then the naturally produced Cyclic GMP would last longer, blood flow into the penis would be enhanced, and the man would have a more turgid penis - which in effect means a harder erection.
All that Viagra, Cialis and Levitra do is suppress, or inhibit, the action of PDE - which is why they are called 'PDE5 Inhibitors'. The value of these drugs, therefore, is that they enhance the action of a man's natural Cyclic GMP and give him a harder erection. They do not GIVE a man a spontaneous erection - all that they do is make him more Erectable, or more responsive to natural sexual stimulation.
The three PDE5 Inhibitors are claimed by their manufacturers to have slightly different actions. Viagra' s action comes on within half an hour of taking the tablet, its period of action (the time during which the man is highly erectable if he is sexually stimulated) lasting for between 4 to 6 hours. Levitra is similar to Viagra in both its onset of action and period of efficacy. Cialis takes longer to become active - the tablet needs to be taken an hour or two before its action is needed. The period of 'erectability' however is longer than for the other two drugs - in most men lasting for 24 to 36 hours.
Men who feel they would benefit from using one of these drugs should consult their physician, in order to make sure that their Erectile Dysfunction is not an early sign of impending heart disease - since narrowing of the blood vessels to the penis may be associated with similar narrowing of blood vessels in the heart (which could put a man at risk of a heart attack).