Based on the results of a Massachusetts study on the study of male aging, it can be assumed that in 1995 there were more than 152 million men suffering from erectile dysfunction (ED) worldwide. According to experts forecasts, by 2025 their number will increase by 170 million people and will amount to 322 million. A significant increase in patients with ED will occur in developing countries. Even if sildenafil is taken, there will be about 11.9 million such patients in Europe by this time, 9.1 million in North America, 19.3 million in Africa, and 113 million in Asia.
Erectile function is a key indicator of the quality of life for many men. Erectile dysfunction is a problem that can affect up to 52% of men aged 40 to 70 years. This raises serious concerns due to the negative impact of ED on self-esteem, quality of life and interpersonal relations in society. Of 52% of men with ED, 17.2% have mild, 25.2% – moderate and 9.6% – severe erectile dysfunction. According to statistics, the incidence of ED correlates with age, but it should be remembered that it is not an inevitable consequence of aging, and old age does not exclude sexual attraction in men. Nevertheless, with increasing life expectancy, the prevalence of ED will inevitably increase. The presence of ED in a man has a negative impact on his partner, causing her secondary sexual dysfunction.
Studies have shown that ED is associated with metabolic syndrome and cardiovascular diseases and is currently considered their marker. The diagnosis of ED can be used for early detection of the risk of cardiovascular diseases.
The discoveries of the last two decades in the field of neurophysiology and molecular biology have led to significant progress in the treatment of patients with ED and associated diseases. A fundamentally new drug has been developed in the treatment of this disease – sildenafil (Viagra), which meets all modern requirements for ED therapy. This drug is a highly effective and reliable oral remedy, has few side effects. According to the mechanism of action, it belongs to the type 5 phosphodiesterase inhibitors (PDE-5). Selective inhibition of PDE-5 improves tolerance to ischemia and hypoxia, therefore, exposure to this enzyme opens up new opportunities for pharmacological correction through NO-dependent mechanisms.
In their work “PDE-5 inhibitors in the treatment of erectile dysfunction: the right drug for the right patient”, Italian researchers G. Corona and N. Mondaini emphasized that ED is a common disorder that affects men all over the world. PDE-5 inhibitors are effective, are well tolerated and are the first-line drugs for the treatment of ED. Currently, this is the “gold standard” in the treatment of ED, and intracavernous drugs, which were widely used before, have now become second-line drugs. First of all, this is due to the high effectiveness of new drugs, and most importantly – with oral administration and ease of use.
The efficacy and safety of sildenafil has been confirmed in patients with ED of various etiologies. By 2003, more than 20 million people worldwide were taking sildenafil with excellent results. Despite the fact that ED was caused by such severe and poorly treatable diseases as radical prostatectomy in patients with prostate cancer, severe diabetes mellitus and spinal cord injuries, sildenafil has demonstrated its effectiveness in such patients as well. The frequency of adverse cardiovascular effects in patients taking sildenafil did not differ from those in the population. The study of the pharmacological effect of sildenafil on the ischemic myocardium also confirms the safety of this drug. Sildenafil has proven to be safe and effective in patients taking various medications, including several antihypertensive drugs at the same time, selective serotonin reuptake inhibitors, cardiovascular and antidiabetic medications.
Taking alcohol in moderate doses does not have any effect on the pharmacokinetics of sildenafil when taken together. Studies have shown that the use of Viagra with alcohol does not lead to changes in cardiac output, heart rate, blood pressure and peripheral vascular resistance. Sildenafil does not enhance the hypotensive effect of alcohol at its concentration in the blood of 0.08%, or 80 mg/dl.
The clinical benefits of sildenafil therapy in countries with a high level of heart diseases, in particular heart failure, were demonstrated by scientists from the Montreal Heart Institute, conducting a retrospective review of the medical records of 16 patients admitted to the center for heart transplantation due to progressive heart failure. Systolic and mean pulmonary artery pressure, transpulmonary pressure gradient, cardiac output and cardiac index were determined in patients. The functional class of heart failure was evaluated according to the criteria of the New York Heart Association (NYHA) at baseline and after 6 months of sildenafil therapy.
Patients received Viagra therapy for 4166 patient-days at an average dose of 102.5 ± 54.0 mg/day. None of the patients dropped out of the study due to the side effects of the drug. After 6 months of treatment, there was an improvement in the cardiac index (p = 0.014), pulmonary artery pressure (p = 0.049) without any significant change in other hemodynamic parameters. In 10 patients (62.5%), there was an improvement in the functional class of heart failure according to NYHA, 8 later underwent a heart transplant (50%), and in 2 the improvement reached such an extent that this operation was avoided (12.5%). The authors concluded that sildenafil therapy in patients with heart failure is well tolerated and significantly improves the functional capabilities of the heart.
Short-term therapy with sildenafil is safe and effective in patients with pulmonary arterial hypertension. However, there are still few data on the effect of sildenafil on the survival of patients with idiopathic pulmonary arterial hypertension. In a study conducted at Peking University, the effect of sildenafil therapy was studied in 77 patients with newly diagnosed idiopathic pulmonary hypertension in the period from 2005 to 2009. Patients were divided into 2 groups: taking sildenafil and traditional therapy. The initial characteristics of patients receiving sildenafil were similar to the comparison group. Patients from the sildenafil group received catheterization of the right parts of the heart initially and after 3 months. After 3-month therapy with sildenafil, a significant improvement was noted during the 6-minute walking test, the consumption of oxygen by the myocardium significantly increased (p < 0.05). One-, two -, and three-year survival rates in patients receiving sildenafil were 88, 72, and 68%, respectively, compared with 61, 36, and 27% in the control group (p < 0.001). A low body mass index and a decrease in myocardial oxygen saturation without the use of sildenafil were independent predictors of fatal outcomes. The use of sildenafil as a pathogenetic therapy is associated with an improvement in the survival rate of patients with idiopathic pulmonary arterial hypertension.
Several experimental studies of sildenafil are devoted to various aspects of its effect on organs and tissues. Sildenafil, in particular, can contribute to the restoration of a bone defect. In a study conducted by scientists, the effect of sildenafil on the healing processes of bone tissue was studied. Of the 42 male rats, half received sildenafil at a dose of 10 mg / kg of weight per day for 30 days and half formed the control group. A small surgical defect of the shin bones was inflicted on the rats, and later on, histological, densitometric and MRI examination of the bone tissue were performed against the background of therapy. At the stages of recovery and healing, statistically significant differences between the groups were obtained, indicating that sildenafil accelerates the process of bone repair. The authors believe that conducting research on the use of sildenafil in the complex therapy of bone tissue restoration seems promising.
Thus, sildenafil is successfully used in the treatment of ED in patients with a wide variety of pathologies as both mono-and combination therapy. The possibility of its use in patients with various somatic diseases is of interest, and the results of clinical studies open up new prospects for its use.