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Viagra inhibit PDE5？what does it means？what will happen if Viagra inhibit PDE5？

Viagra inhibit PDE5？what does it means？what will happen if Viagra inhibit PDE5？

Chemistry: The Molecular Science
Chemistry: The Molecular Science
5th Edition
ISBN:9781285199047
Author:John W. Moore, Conrad L. Stanitski
Publisher:John W. Moore, Conrad L. Stanitski
Chapter10: Fuels, Organic Chemicals, And Polymers
Section: Chapter Questions
Problem 119QRT
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Viagra inhibit PDE5？what does it means？what will happen if Viagra inhibit PDE5？
Silverman & Holladay Discovery of Drugs through Clinical Observations The impotence drug sildenafil citrate (Viagra) was designed for the treatment of angina and hypertension by blocking the enzyme phosphodiesterase-5, which hydrolyzes cyclic guanosine monophosphate (CGMP), a vasodilator that allows increased blood flow. In 1991, sildenafil went into Phase I clinical trials for angina. In Phase II clinical trials, it was not as effective against angina as Pfizer had hoped, so it went back to Phase I clinical trials to see how high of a dose could be tolerated. It was during that clinical trial that the volunteers reported increased erectile function. Given the weak activity against angina, it was an easy decision to try to determine its effectiveness as the first treatment for erectile dysfunction. Sildenafil works by the mechanism for which it was designed as an antianginal drug, except it inhibits the phosphodiesterase in the penis (phosphodiesterase-5) as well as the one in the heart. Sexual stimulation causes release of nitric oxide in the penis. Nitric oxide is a second messenger molecule that turns on (pun intended) the enzyme guanylate cycla converts guanosine triphosphate to CGMP. NO L-Arg Nitric oxide ,which Synthase Stimulates Erection Guanylate cyclase Increased blood flow The vasodilator relaxes the smooth muscle in the corpus cavernosum, allowing blood to flow into the penis, thereby producing an erection. GTP Smooth CGMP- muscle relaxation GMP Vasoconstriction PDE 5 However, phosphodiesterase-5 (PDE-5) hydrolyzes the CGMP, which causes vasoconstriction and the outflow of blood from the penis. Sildenafil inhibits this phosphodiesterase, preventing the hydrolysis of CGMP and prolonging the vasodilation effect. Inhibits Viagra
Transcribed Image Text:Silverman & Holladay Discovery of Drugs through Clinical Observations The impotence drug sildenafil citrate (Viagra) was designed for the treatment of angina and hypertension by blocking the enzyme phosphodiesterase-5, which hydrolyzes cyclic guanosine monophosphate (CGMP), a vasodilator that allows increased blood flow. In 1991, sildenafil went into Phase I clinical trials for angina. In Phase II clinical trials, it was not as effective against angina as Pfizer had hoped, so it went back to Phase I clinical trials to see how high of a dose could be tolerated. It was during that clinical trial that the volunteers reported increased erectile function. Given the weak activity against angina, it was an easy decision to try to determine its effectiveness as the first treatment for erectile dysfunction. Sildenafil works by the mechanism for which it was designed as an antianginal drug, except it inhibits the phosphodiesterase in the penis (phosphodiesterase-5) as well as the one in the heart. Sexual stimulation causes release of nitric oxide in the penis. Nitric oxide is a second messenger molecule that turns on (pun intended) the enzyme guanylate cycla converts guanosine triphosphate to CGMP. NO L-Arg Nitric oxide ,which Synthase Stimulates Erection Guanylate cyclase Increased blood flow The vasodilator relaxes the smooth muscle in the corpus cavernosum, allowing blood to flow into the penis, thereby producing an erection. GTP Smooth CGMP- muscle relaxation GMP Vasoconstriction PDE 5 However, phosphodiesterase-5 (PDE-5) hydrolyzes the CGMP, which causes vasoconstriction and the outflow of blood from the penis. Sildenafil inhibits this phosphodiesterase, preventing the hydrolysis of CGMP and prolonging the vasodilation effect. Inhibits Viagra
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