(206) Strategies of Nitric Oxide Augmentation for PDE5 Inhibitors
Authors: Khan Bhadar M , Shah S 
Published: March 2024

Abstract

Introduction
Erectile function and endothelial functions are closely related entities. Nitric oxide NO regulates circulation and microcirculation involved in erection.NO concentration is reduced with aging, diabetes, environment pollution smoking, obesity, inflammation, high prolactin, low testosterone oxidative stress and atherosclerosis. Many of erectile dysfunction patients are PDE5 inhibitor resistant. Strategies to enhance NO expression, can be employed to convert treatment resistant patient into responder.

Objective
Employ every possible mechanism to augment nitric oxide expression. Greater base line nitric oxide better would be PDE5 inhibitor respose.

Methods
Internet search was made on various website including pub med, science direct, google scholars using key words like erection, erectile dysfunction, nitric oxide, l arginine, oxidative stress, antioxidant, NOS, endothelial dysfunction, atherosclerosis and etc. This was followed by literature study on given topic.

Results
Efficacy of PDE 5 inhibitor in ED treatment is 70%. NO concentration decline to 50% by age of 40 and is only 15% at age 60. Humming can increase nasal NO level up to 15 time.

Conclusions
NO regulates endothelial function, vasodilatation, platelet aggregation inhibition, free radical scavenging, testosterone synthesis and neuronal protection. Study of mechanism of NO production provides, strategies for its enhancement. L arginine, L citrulline, serve as substrate and vitamin C, tetrahydrobiopterin (BH4) act as co factors in production of NO. Endothelial nitric oxide synthase e NOS, neuronal nitric oxide synthase n NOS are major enzymes act involved in synthesis. Oxygen is required for NO synthesis process. Supplementation of substrate and cofactors help increase NO levels. Oxygen availability can be increased through exercise and raising hemoglobin level. Reactive oxygen species ROS convert NO into bioinactive peroxynitrite which itself is ROS. Oxidative stress can cause endothelial nitric oxide synthase uncoupling. Consequently eNOS start producing ROS. This causes oxidation of NOS and as well as of cofactor like BH4 and vitamin C. ROS also increase level of methylarginines. Antioxidant used to neutralize ROS include Co Q10, alpha lipoic acid, flavonoids, bioflavonoids poly phenols, pycnogenol, resveterol, fulvic acid and etc. Second mechanism NO production is from dietary nitrates. Nutritional nitrates are converted into nitrite by oral anaerobic bacteria’s. Nitrate rich foods like beet root or spinach are added to enhance nitrate based NO. Nitric oxide thus produced is used for vasodilatation of penile vessels as well sinuses of corpus cavernousm. Apart from that it inhibits uncoupling of NOS. This support L arginine based mechanism of NO production. Nitroglycerin or minoxidal act as NO donors. These agents can be used locally at glans penis to augment NO availability. Bee breathing is maneuver in which humming sound vibrates nasal sinus increasing NO production up to 15 folds. Inhaled NO act as bronchodilator which increase lung capacity leading to higher blood oxygen concentration. Various NO enhancement strategies thus applied, may convert non responder PDE5 inhibitor to responders.

Disclosure
No.