Sildenafil

Updated on All content is checked by medical journalists.

The active ingredient Sildenafil stimulates potency and is therefore used against erectile dysfunction (impotence). It is also used for pulmonary hypertension. The potency-increasing effect of Sildenafil was discovered by chance, because originally a new heart drug was sought. Here you can read everything you need to know about the effects, side effects and use of Sildenafil.

This is how sildenafil works

Sildenafil is a so-called PDE-5 inhibitor (phosphodiesterase-5 inhibitor). It inactivates the enzyme PDE-5 so that the erection-promoting cyclic guanosine monophosphate (cGMP) is no longer broken down.The result: the blood vessels remain relaxed and erectile function improves. Accordingly, sildenafil has a vasodilating and blood pressure lowering effect.

During sexual stimulation, the nerve messenger substance (neurotransmitter) nitrogen oxide (NO) is released in the erectile tissue of the penis. NO increases the amount of another messenger substance, the so-called cGMP. As a result, the muscles in the erectile tissue relax and the blood vessels widen. So more blood flows in, which leads to an erection. Finally, the cGMP is broken down by the enzyme PDE-5, which narrows the vessels again - the penis relaxes.

PDE-5 inhibitors such as sildenafil also develop their vasodilating effects in the lungs. You can therefore counteract the high blood pressure (pulmonary hypertension) that prevails there.

Uptake, breakdown and excretion

The active ingredient reaches its maximum concentration in the blood plasma around 60 minutes after ingestion. Four hours after ingestion, half of the active ingredient is broken down again. The liver is mainly responsible for the breakdown.

When is Sildenafil used?

Sildenafil is primarily used for erectile dysfunction (ED, impotence). This occurs when a man has been unable to achieve or maintain an erection for at least six months.

Sildenafil has recently also been used to treat pulmonary hypertension (high lung pressure). It has been approved for this application in the EU and Switzerland since 2006.

This is how sildenafil is used

Sildenafil is mainly used in the form of tablets. The dose is usually started with the lowest dose.

For erectile dysfunction (ED), one tablet is taken about an hour before sexual intercourse. If necessary, the dosage can be increased in consultation with the doctor. The maximum sildenafil dosage for ED is 100 milligrams per day and must not be exceeded. The dosage must be adjusted in the elderly and in patients with impaired liver and kidneys.

The intake should be started here with 25 milligrams. A dose increase is possible in consultation with the doctor. The preparations usually contain the active ingredient in the form of salts (sildenafil citrate).

What side effects does Sildenafil have?

Very common side effects are headache, attacks of reddening of the skin (flush) and visual disturbances with sensitivity to light and blurred vision. In addition, nasal congestion, dizziness and an acute skin rash (exanthema) are common.

Very serious undesirable effects from the sexual enhancer are myocardial infarction and sudden cardiac death, stroke (apoplexy) and the occlusion of retinal vessels.

In the past there have been many deaths in connection with the use of the sexual enhancer, for example due to a heart attack. Therefore, before using Sildenafil, the contraindications must be observed.

What should be considered when taking sildenafil?

Contraindications

Sildenafil must not be taken if:

• Hypersensitivity to the active substance or any of the components
• recent heart attack or stroke
• severe cardiovascular diseases such as heart failure (heart failure) or unstable angina pectoris (tight chest)
• simultaneous intake of nitrates (e.g. nitroglycerin, ISMN) or other NO donors (e.g. molsidomin, riociguat)
• low blood pressure (less than 90/50 mmHg)
• Eye diseases such as ischemic optic neuropathy or hereditary diseases of the retina (e.g. retinitis pigmentosa)
• severe liver or kidney impairment

Interactions

The simultaneous use of vasodilating drugs such as so-called NO donors (e.g. nitrates, molsidomine, nicorandil, amyl nitrite, sodium nitroprusside) can lower blood pressure considerably. To avoid life-threatening consequences, Sildenafil must therefore not be used together with such drugs.

For the same reason, patients with a heart attack who have previously taken sildenafil should not be treated with nitrates in an emergency. Blood pressure is also dangerously lowered in combination with high blood pressure drugs such as so-called alpha blockers (e.g. doxazosin).

Sildenafil is mainly broken down by the liver by certain liver enzymes (CYP3A4 and, to a lesser extent, CYP2C9). These enzymes can be inhibited by some drugs (CYP inhibitors), which can enormously increase both the effect and the side effects of Sildenafil.

For this reason, the sexual enhancer must not be used together with CYP3A4 inhibitors. These include, for example, the antifungal agents ketoconazole and itraconazole, the antibiotic erythromycin, the gastric agent cimetidine, and the HIV agents saquinavir and ritonavir.

The activity of the liver enzymes can also be increased by some drugs (CYP inducers). This will reduce the effectiveness of Sildenafil. Examples of CYP3A4 inducers are the epilepsy drugs phenobarbital, phenytoin and carbamazepine. But St. John's wort can also accelerate the breakdown of sildenafil and thus weaken its effect.

Age restriction

Sildenafil drugs used to treat pulmonary hypertension (pulmonary arterial hypertension) can be used in children from one year of age. In this indication, women also receive the active ingredient.

Drugs for the treatment of erectile dysfunction, on the other hand, are only approved for male adults aged 18 and over.

pregnancy and breast feeding period

Experience with taking sildenafil during pregnancy and breastfeeding is extremely limited, as the active ingredient has only recently been approved for women of childbearing age. The information for healthcare professionals speaks out against taking it due to a lack of data. If use is absolutely necessary, a strict risk-benefit assessment is assumed.

How to get medication with sildenafil

In Germany, Austria and Switzerland, Sildenafil can only be bought with a prescription, so it requires a prescription.

Before the prescription is given, the doctor examines the patient if the patient is particularly at risk of developing certain side effects due to previous illnesses (such as heart problems).

The prescription requirement applies not only to the original preparation, but also to generic sildenafil. You can buy the sexual enhancer on the Internet without a prescription, but this is illegal. Above all, however, neither the sildenafil dosage nor the purity and thus the effectiveness and safety are guaranteed with such preparations. It is therefore not advisable to buy the sexual enhancer over the Internet without a prescription.

Since when is sildenafil known?

Sildenafil, the well-known blue pill, was developed in the 1990s. The active ingredient was approved in the EU and Switzerland in 1998.

In 2013, the patent protection for the sexual enhancer expired in Germany. Since then, numerous generic sildenafil drugs have been on the market. In the USA, the patent for sildenafil did not expire until 2019.

Tags:  alcohol book tip travel medicine