Sildenafil

The active substance Sildenafil has been under the well-known brand name of the American pharmaceutical company Pfitzer since 1998 Viagra marketed as a drug for erectile dysfunction. Sildenafil is also part of various generics and has been under the name since 2006 Revatio used as a remedy for pulmonary arterial high blood pressure.

What is Sildenafil?

Sildenafil is a synthetically produced so-called PDE-5 inhibitor. Medicines of this substance class (other examples from https://nizagara-online.net are Tadalafil and Vardenafil, the active ingredients of the sexual enhancers Cialis and Levitra) intervene in the regulation of the tone of the smooth muscles of the vascular walls and have a vasodilating effect.

Its effect is based on the blocking of the cGMP-cleaving enzyme phosphodiesterase type 5 (PDE-5), it is the basis of both the potency-increasing and blood pressure-lowering effects of Sildenafil. Medicines containing Sildenafil require a prescription in Germany.

Pharmacological effect

The regulation of blood pressure at the level of the smooth muscles of the vessel walls, especially in the pulmonary circulation and in the penis, is characterized by the interplay between the messenger substance nitric oxide (NO) and the enzyme phosphodiesterase 5 (PDE-5).

Release of NO at nerve endings near blood vessels stimulates the synthesis of the nucleotide cGMP (cyclic guanosine monophosphate cGMP is a relative of the universal energy molecule ATP). Finally, cGMP causes the smooth muscles to relax via a further signal cascade, thus expanding the cross-section of the blood vessels. The blood pressure drops. In the event of sexual arousal, this mechanism enables the erectile tissue of the penis to be filled with rapidly flowing blood and thus contributes significantly to the development of an erection.

The regulatory antagonist of NO is PDE-5, which breaks down cGMP again and thus promotes the renewed narrowing of the vascular walls. PDE-5 is often too active in men with high blood pressure and / or erectile dysfunction. Will the enzyme go through Sildenafil blocked, the cGMP level rises. This generally has an antihypertensive effect. The duration and strength of an erection are positively influenced by Sildenafil.

Medical application & use

Sildenafil is used in the treatment of erectile dysfunction and high blood pressure.

For erectile dysfunction, the drug is taken when needed - but not without prior consultation with a doctor. The typical dose is between 25 and 100 milligrams, depending on the severity of the disorder. Sildenafil unfolds its effects within about two hours and is active in the body for up to 10 hours after ingestion.

A resulting erection can be effectively stabilized by the active ingredient within this period. Sildenafil alone does not induce an erection - sexual arousal as well as intact mechanisms of NO release and cGMP synthesis are prerequisites for the effectiveness of drugs that contain Sildenafil.

If Sildenafil is prescribed to be taken regularly as a blood pressure lowering agent, a dose of around 60 milligrams is usually spread over the day.

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Risks & side effects

Type and extent of side effects experienced by users of Sildenafil occur are individually different. Most of these side effects are related to the drug's vasodilatory effects.

Sildenafil is completely free of side effects for only about a fifth of users. Headache, blocked or runny nose, flushing of the face, stomach and digestive discomfort, sweats and hot flashes, back pain and body aches are common side effects. Users rarely also complain of dizziness, delayed responsiveness or visual disturbances. Another side effect can be the unwanted persistence of an erection. These effects are not worrying and wear off within a day or two.

Occasionally, regular users of high doses of sildenafil have had sudden hearing loss, i.e. sudden hearing loss. Also very rarely there was an insufficient supply of oxygen to the optic nerve due to a sharp drop in blood pressure in the eye (anterior ischemic optic neuropathy) and thus partial or complete loss of vision. However, these complications only occurred in men who had additional risk factors for such damage.

Because sildenafil lowers blood pressure, other antihypertensive drugs or drugs can cause a life-threatening drop in blood pressure. This applies to the popular drug amyl nitrite, known under the name Poppers, and in particular also to nitrate-containing agents such as nitroglycerin, which are used in emergency medicine for heart failure.