The main group of drugs are inhibitors

As can be understood from the mechanisms of a normal erection, impotence may develop due to hormonal deficiency, disorders of the neural system, lack of adequate penile blood supply or psychological problems.[17] Restriction of blood flow can arise from impaired endothelial function due to the usual causes associated with coronary artery disease, but can also be caused by prolonged exposure to bright light. Once an erection is achieved, the man places the elastic ring on the base of his penis, which keeps blood from draining from the penis back into the body. Prescribed drugs used to treat high blood pressure, ulcers, depression, and prostate cancer, as well as medications to prevent baldness or aid in dieting, can have side effects that include impotence. Stimulation of the penile shaft by the nervous system leads to the secretion of nitric oxide (NO), which causes the relaxation of smooth muscles of corpora cavernosa (the main erectile tissue of penis), and subsequently penile erection. In all, these studies proved that Tribulus works very well in curing sexual dysfunctions and maximizing sexual performance when taken regularly.

Be sure to select a Tribulus extract that contains at least 45% protodioscin.. It is estimated to affect between 10 million and 15 million men in the United States alone. More than nine clinical studies performed by six universities and academic hospitals on this purified extract have confirmed the herb's beneficial effect.

Other studies have suggested that Tribulus also acts by increasing the level of dehydroepiandrosterone (DHEA), a naturally occurring substance in the body believed to be important for a healthy sex drive. There are two methods for measuring changes in penile rigidity and circumference during nocturnal erection: snap gauge and strain gauge. When pharmacological methods fail, a purpose-designed external vacuum pump can be used to attain erection, with a separate compression ring fitted to the penis to maintain it. These studies showed that Tribulus helps treat impotence caused by low testosterone levels or an imbalance in the body's level of sex hormones. Modern drug therapy for ED made a significant advance in 1983, when British physiologist Giles Brindley dropped his trousers and demonstrated to a shocked Urodynamics Society audience his papaverine-induced erection.[30] The drug Brindley injected into his penis was a non-specific vasodilator, an alpha-blocking agent, and the mechanism of action was clearly corporal smooth muscle relaxation. This form typically comes on gradually and is usually more easily treatable than primary impotence. It is normal for a man to have five to six erections during sleep, especially during rapid eye movement (REM). One of the most underestimated causes of impotence is cigarette smoking — as if you need yet another reason to quit. A useful and simple way to distinguish between physiological and psychological impotence is to determine whether the patient ever has an erection.