Currently, due to the increase in life expectancy in men, the detection and treatment of erectile dysfunction is the most important aspect of maintaining men’s health.
Erectile dysfunction (ED) is the inability to achieve and (or) maintain an erection sufficient for sexual intercourse, in half or more of the cases persisting for 3 months or more.
In the course of a standardized questionnaire survey of 600 men aged 40 to 70 years, conducted in 4 countries of the world, the following results were obtained. In Brazil, the incidence of ED is 15%, in Italy it is 17%, in Malaysia it is 22% and in Japan, it is 34%.
Research was conducted in the early 90s. 20th century and ongoing, indicate the existence of close links between ED and cardiovascular disease, as well as the influence of age on the prevalence of this disease. Depending on the design of the study, the prevalence of ED ranges from 10% to 52%, and in some countries, the increase in the number of such patients is 25–30 new cases per 1,000 inhabitants per year. Mild ED affects 17.2% of men, moderate – 25.2%, and severe – 9.6%
An erection is an increase in the volume of the penis with a sharp increase in its elasticity, due to the stretching and filling of the cavernous bodies during sexual arousal. The erection phenomenon is caused by a complex combination of neurovascular changes in the cavernous bodies of the penis, the final link of which is the relaxation of the smooth muscle elements of the arteries, arterioles, and sinusoids. With sexual stimulation, the parasympathetic nervous system is activated. The release of neurotransmitters, in particular, nitric oxide from the vascular endothelium of the cavernous bodies, leads to the accumulation of cGMP in the cavernous tissue and the relaxation of smooth muscle cells in the walls of the afferent arteries and cavernous bodies. Filling the lacunae with arterial blood causes compression of the venules and blocks the outflow of blood from the penis.
Depending on the etiology, psychogenic and organic ED are distinguished, although in most cases both factors are involved in the development of this disease (the so-called mixed form). The main psychological factors are depression, relationship problems, sexual ignorance, fear of failure, etc. Organic ED can develop in various somatic diseases: diabetes mellitus, arterial hypertension, hypercholesterolemia, hypogonadism, hypothyroidism, and smoking. Numerous studies have shown a significant association of ED with metabolic syndrome and cardiovascular disease. That is why ED is currently considered an early marker of these diseases.
The prevalence of ED in persons without somatic pathology is 15.4%, and with concomitant cardiovascular diseases, ED is detected almost 10 times more often, accounting for 66.4%.
ED is detected in every third man with arterial hypertension (AH), in every second man with coronary heart disease (CHD), and when they are combined, in 2/3 of patients. Diabetes mellitus (DM) is one of the diseases that negatively affect sexual function. The development of ED in patients with type 2 diabetes is also due to endothelial disorders. One study showed that the prevalence of ED and decreased libido in type 2 diabetes were 60.9% and 46.4%, respectively.
ED is detected in every third man with arterial hypertension, in every second man with coronary heart disease, and when they are combined, in 2/3 of patients. Diabetes mellitus also belongs to diseases that negatively affect sexual function.
In 80% of cases, ED is organic in nature and is a complication of somatic diseases. Various mechanisms, both neurogenic and vascular, may be involved in the development of ED, and its treatment should primarily be pathogenetic.
In the late 90s. of the last century, phosphodiesterase-5 (PDE-5) inhibitors were synthesized, which served as a turning point in the treatment of erectile dysfunction. The first selective PDE-5 inhibitor, sildenafil, was developed as an antianginal drug. The antianginal effect of the drug was insignificant, but the men who participated in the study noted the beneficial effect of the drug on erectile function.
In this regard, sildenafil began to be investigated as a drug used in the treatment of ED. Later, vardenafil and tadalafil were used to treat ED. All of these drugs are effective in the treatment of ED but differ in pharmacokinetics and side effects.
The mechanism of action of PDE-5 inhibitors is based on the blockade of cGMP hydrolysis, which leads to a sharp increase in its concentration, activation of cGMP-dependent protein kinase, followed by phosphorylation of ion channels, resulting in a decrease in the concentration of calcium in