Sildenafil is a phosphodiesterase type 5 (PDE5) inhibitor. Phosphodiesterase type 5 is an enzyme that plays a significant role in the regulation of cGMP signalling pathway in various processes, including contraction and relaxation of smooth muscles. Inhibitors of these enzymes lead to changes in normal physiological processes. It is an FDA-approved drug for the treatment of erectile dysfunction in men.

Sildenafil, sold under the brand name Viagra, was first developed by Pfizer for the treatment of angina and pulmonary hypertension. Later, Pfizer decided to market it for the treatment of erectile dysfunction when researchers found its potential in treating this condition. Currently, it is being studied for the treatment of pulmonary hypertension, urinary incontinence and other conditions. If you are considering research in this area, you can buy liquid Viagra from Element Sarms to aid your research.

From Pubchem

IUPAC Name:5-[2-ethoxy-5-(4-methylpiperazin-1-yl)sulfonylphenyl]-1-methyl-3-propyl-6H-pyrazolo[4,3-d]pyrimidin-7-one
Synonym: 139755-83-2, Aphrodil, Vizarsin, Patrex
Molecular Formula: C22H30N6O4S
Molecular Weight: 474.6 g/mol
CAS Number: 139755-83-2
PubChem CID: 135398744

1. Sildenafil Erectile Dysfunction

Sildenafil has already been approved for the treatment of erectile dysfunction in men. The release of nitric oxide in the erectile tissues leads to the production of cGMP, which facilitates increased blood flow in the penis, resulting in an erection. Researchers speculate that this pathway may also play a role in the component of sexual dysfunction in women. However, studies show that it didn’t significantly improve sexual function in post-menopausal women [1, 2].

Further studies found that sildenafil can improve antidepressant-associated sexual dysfunction in both men and women. In a study, forty-nine female patients taking serotonin reuptake inhibitors were randomized to receive either 50mg-100mg drug or placebo before sexual activity. The result found that treated patients observed a significant improvement in sexual function as compared to the placebo group [3, 4].

Moreover, sildenafil also proved to be successful in managing erectile dysfunction in male patients with spinal cord injury. It has been shown to cause high patient acceptance and satisfaction at a 50 mg dose. However, the efficacy is linked to intact sacral or thoracolumbar spinal segments (S2–S4 or T10–L2), critical for psychogenic erections. Complete disruption of neurogenic signals prevents successful treatment [5].

2. Sildenafil and Pulmonary Hypertension

Sildenafil has been extensively studied to check if it can benefit patients with pulmonary hypertension. Pulmonary Hypertension Group 1 is characterized by increased arterial pressure in lung arteries due to their constriction and rigidity. In contrast, Group 2 pulmonary hypertension stems from malfunctioning heart valves, leading to blood accumulation and increased pressure in the lungs.

Studies show that sildenafil is effective for the treatment of pulmonary hypertension group 1. Results from SUPER trials 1 and 2 found that sildenafil effectively improved hemodynamic parameters in patients with pulmonary arterial hypertension. Additionally, it was well-tolerated over a span of three years, and participants demonstrated improved functional status throughout this duration [6, 7]. This led to the approval of REVATIO (sildenafil) from the FDA for the treatment of pulmonary hypertension group 1 in adults.

Further studies were conducted to explore the efficacy of pre-operative sildenafil on the intraoperative hemodynamic parameters. A meta-analysis of three studies reveals that this drug can decrease intra-operative and post-operative pulmonary arterial pressure without affecting other systemic hemodynamic parameters [8].

One study found that sildenafil in combination with milrinone was superior in treating persistent pulmonary hypertension in neonates as compared to monotherapy with either drug. Further, it is recommended to use the combination in resource-limited settings [9].

3. Sildenafil and Exercise Capacity

In pulmonary artery hypertension (PAH), blood flow doesn’t increase with exercise despite high blood pressure. This results in a lack of oxygen delivery to muscles, causing dyspnea and reduced exercise tolerance. Studies from SUPER trials found that it can improve exercise capacity in patients with PAH. In one study, 28 patients were randomized to receive sildenafil or placebo. Results found that sildenafil caused improvement in PETCO2, VE/VCO2, peak O2 pulse and peak VO2 as compared to controls, indicating enhanced exercise tolerance [10].

4. Sildenafil and Alopecia

Sildenafil has been shown to improve alopecia. In one study, researchers compared the effect of topical sildenafil citrate solution and topical minoxidil in treating female pattern hair loss. The results found that sildenafil led to increased vellus hair count in the frontal, temporal and vertex sides. Further, it caused improvement in terminal hair count and thickness in the frontal, temporal and vertex sides. Sildenafil 1% proved to be more effective for female pattern hair loss than 5% minoxidil [11].

Similarly, another study in males found that sildenafil increased vertical and total hair count at 18cm and 24cm points as compared to placebo. Further, it increased vertical hair count in the temporal side [12].

5. Sildenafil and Raynaud phenomena

Raynaud's phenomenon refers to temperature-sensitive vasospasms in the fingers and toes, causing the skin to become pale and then bluish due to poor blood circulation. Sildenafil is often used off-label for the treatment of this condition. Studies show that sildenafil is effective and well-tolerated in Raynaud phenomena patients [13, 14].

6. Current Status of Sildenafil

Sildenafil is an extensively researched drug. It has been approved by FDA for the treatment of erectile dysfunction and pulmonary hypertension group 1. Further, people buy Viagra for the off-label use of alopecia. Many clinical trials are ongoing to explore its effect on urinary incontinence, skin reactions and other conditions. We offer Viagra in liquid form for sale for research in animals and humans. At Element SARMS, viagra purchase is exclusively available for research purposes.

1. Efficacy and Safety of Sildenafil Citrate in Women with Sexual Dysfunction Associated with Female Sexual Arousal Disorder. Journal of Women's Health & Gender-Based Medicine, 2002. 11(4): p. 367-377.
2. Kaplan, S.A., et al., Safety and efficacy of sildenafil in postmenopausal women with sexual dysfunction. Urology, 1999. 53(3): p. 481-486.
3. Nurnberg, H.G., et al., Treatment of Antidepressant-Associated Sexual Dysfunction With Sildenafil: A Randomized Controlled Trial. JAMA, 2003. 289(1): p. 56-64.
4. Nurnberg, H.G., et al., Sildenafil Treatment of Women With Antidepressant-Associated Sexual Dysfunction: A Randomized Controlled Trial. JAMA, 2008. 300(4): p. 395-404.
5. Schmid, D.M., B. Schurch, and D. Hauri, Sildenafil in the Treatment of Sexual Dysfunction in Spinal Cord–Injured Male Patients. European Urology, 2000. 38(2): p. 184-193.
6. Galiè, N., et al., Sildenafil citrate therapy for pulmonary arterial hypertension. N Engl J Med, 2005. 353(20): p. 2148-57.
7. Rubin, L.J., et al., Long-term treatment with sildenafil citrate in pulmonary arterial hypertension: the SUPER-2 study. Chest, 2011. 140(5): p. 1274-1283.
8. Villanueva, D.L.E., R.D. Agustin, and E.J. Llanes, Pre-Operative Sildenafil for Patients With Pulmonary Hypertension Undergoing Mitral Valve Surgery: A Systematic Review and Meta-Analysis. Cardiol Res, 2019. 10(6): p. 369-377.
9. El-Ghandour, M., B. Hammad, M. Ghanem, and M.A.M. Antonios, Efficacy of Milrinone Plus Sildenafil in the Treatment of Neonates with Persistent Pulmonary Hypertension in Resource-Limited Settings: Results of a Randomized, Double-Blind Trial. Pediatric Drugs, 2020. 22(6): p. 685-693.
10. Oudiz, R.J., et al., Effect of sildenafil on ventilatory efficiency and exercise tolerance in pulmonary hypertension. European Journal of Heart Failure, 2007. 9(9): p. 917-921.
11. Mostafa, H.A., H.A.K. Mohammed, and I. Fouda, Comparative Study Between the Efficacy and Safety of Topical Sildenafil Citrate Solution and Topical Minoxidil 5%in the Treatment of Female Pattern Hair Loss. 2022.
12. Al-Shabkhon, A.A., A.A. Halim Emam, and A. Abd Elfattah Afify, Comparative study between the efficacy of topical sildenafil and topical minoxidil in the treatment of male androgenic alopecia. QJM: An International Journal of Medicine, 2021. 114(Supplement_1).
13. Fries, R., K. Shariat, H.v. Wilmowsky, and M. Böhm, Sildenafil in the Treatment of Raynaud’s Phenomenon Resistant to Vasodilatory Therapy. Circulation, 2005. 112(19): p. 2980-2985.
14. Herrick, A.L., et al., Modified-release sildenafil reduces Raynaud's phenomenon attack frequency in limited cutaneous systemic sclerosis. Arthritis & Rheumatism, 2011. 63(3): p. 775-782