Cialis. Cialis Pharmacological Properties
Viagra was discovered by Pfizer scientists during an investigation into a potential treatment for hypertension. Scientists discovered that, though the drug had little discernible impact on high blood pressure, it did cause the user to develop an erection. Four years later, the drug was patented and released for sale around the world.
The drug, commonly sold as 'Viagra', made $2 billion in its two years on the market. Pharmaceutical company ICOS had been working on another PDE-5 inhibitor since 1993, and both Levitra and Cialis were patented ten years later.
These treatments work on the same basis as, inhibiting the PDE5 and replacing the enzyme with itself, allowing greater flow of NO in the blood stream, and consequent relaxation of penile artery muscle and easier blood flow.
The key difference between the treatments are the active ingredients: Cialis is based on Tadalafil, Viagra Sildenafil. Although the Sildenafil-based Viagra has received more press attention than other pharmacological impotence treatments, Tadalafil has the advantage of working on the system for up to 36 hours – compared with the 8 hours for which users of Viagra are capable of developing an erection.
Clinical trials of Cialis have provided consistently positive results in terms of strength and frequency of successful erections, maintaining an erection during intercourse, and user confidence in the treatment.
Cialis encourages blood flow to the penis only when the user is sexually aroused and after intercourse the erection will disappear, although the user will maintain the ability to develop an erection for up to 36 hours.