PDE-5 inhibitors for erectile dysfunction

PDE-5 inhibitors

Getting stuck in bed can quickly cause uncertainty. This is where PDE-5 inhibitors can help: This group of active ingredients is found in most sexual enhancers – including Viagra – and effectively combats erectile dysfunction.

The essentials in brief

  • PDE-5 inhibitors are used to treat erectile dysfunction used
  • Sildenafil, Tadalafil, Vardenafil, and Avanafil are PDE-5 inhibitors
  • PDE-5 inhibitors can differ in terms of the duration of their effects, the recommended dosage, and their effects and side effects
  • Sexual arousal is a prerequisite for the effect of PDE-5 inhibitors
  • PDE-5 inhibitors require a prescription

“Phosphodiesterase-5 inhibitors – sounds complicated, but it seems very simple: Active ingredients of this grouping block enzymes that stop the man’s erection. Accordingly, when a man takes PDE-5 inhibitors, he has a better and longer erection.”

What are PDE-5 Inhibitors?

Phosphodiesterase-5 inhibitors, or PDE-5 inhibitors for short, describe a group of active substances that are used in particular to treat erectile dysfunction. The best-known representative of the PDE-5 inhibitor is sildenafil, which is found in the drug Viagra. However, Viagra is just one of many drugs that work via PDE-5 inhibitors. A distinction is made between 4 active ingredients, including the new active ingredient Avanafil:

These 4 different PDE-5 inhibitors work in a similar way and all of their help with erectile dysfunction. Nevertheless, aspects such as the effects and side effects, the duration of the effect, or the dose required can differ.

Medical background

Since PDE-5 inhibitors lower blood pressure, they are used not only to treat erectile dysfunction but also to treat high blood pressure in the lungs (pulmonary hypertension).

Beware of high blood pressure

Men with high blood pressure must be careful when taking PDE-5 inhibitors to ensure that their blood pressure remains stable. The active ingredient lowers blood pressure, which can lead to sudden cardiovascular problems.

Who are PDE-5 inhibitors suitable for?

PDE-5 inhibitors are mainly prescribed to men with erectile dysfunction (ED). ED is when the erection is insufficient for satisfactory sexual intercourse.

Warning: Not everyone with erectile dysfunction should use PDE-5 inhibitors. For example, taking it in the case of specific underlying diseases or in combination with other drugs can be harmful to health and, in extreme cases, be life-threatening!

How do PDE-5 inhibitors work

inhibit (as the name suggests) the enzyme phosphodiesterase-5 (PDE-5). To understand why this helps with erectile dysfunction, let’s first look at how an erection develops and disappears again …

Release of the messenger substances

When sexually aroused, the messenger substance “cyclic guanine monophosphate” (cGMP) is released.

The penis becomes stiff

The messenger substance cGMP causes the penile vessels to widen, which allows blood to flow more intensely into the erectile tissue of the penis. The veins in the penis are squeezed off by the pressure of the erectile tissue so that the blood can no longer flow out. The penis becomes stiff.

Prevent the sagging

The enzyme phosphodiesterase-5 (PED-5) breaks down cGMP. If there is too much PDE-5, the blood flows out of the penis and the penis becomes slack.

Maintain an erection

PDE-5 inhibitors block the enzyme PDE-5. This increases the concentration of the messenger substance cGMP and the erection can be maintained.

In the case of erectile dysfunction, the phosphodiesterase-5 inhibitors come into play: They block the erection-counteracting enzyme PDE-5. This increases the concentration of the messenger substance cGMP and you get a long-lasting erection.


PDE-5 inhibitors ensure that the biological processes that enable an erection to dominate the processes that prevent penile stiffening.

PDE-5 inhibitors improve erectile function

PDE-5 inhibitors do not cause an erection. You can only improve a latent erectile function, i.e. positively influence the strength and duration of the erection. Sexual arousal is a prerequisite for this.

PDE-5 inhibitors in comparison

The different PDE-5 inhibitors (Sildenafil, Tadalafil, Vardenafil, and Avanafil) work in a similar way and all show the same effect: a strengthened and prolonged erection. Nevertheless, the active ingredients are sold under different names and can differ in terms of effects and side effects, duration of effect, or required dose.

Viagra: The best known PDE-5 inhibitor

The drug Viagra is probably the best-known sexual enhancer on the market. Its effect on erectile function was discovered by accident when researchers at Pfizer Central Research in the UK were looking for a drug to treat coronary heart disease. In their study, however, the patients showed improved and prolonged erections instead of the desired effects. The small blue tablets have been on the US market since 1998 and everyone is talking about the brand name Viagra. Since then, three other new PDE-5 inhibitors have also come onto the market: Tadalafil, Vardenafil, and the completely new active ingredient Avanafil.

Taking PDE-5 inhibitors

The PDE-5 inhibitors avanafil, sildenafil, tadalafil, and vardenafil are all taken in the form of tablets. If you have problems swallowing, you can switch to melting or chewable tablets for some active ingredients. Ideally, the PDE-5 inhibitor is taken on an empty stomach, as the active ingredient takes longer to develop its effect on a full stomach. The active ingredient is taken a certain time before the planned sexual intercourse so that it can develop its full effect by then.

PDE-5 inhibitors as long-term medication?

PDE-5 inhibitors can be taken as needed, but not more than once a day. Under no circumstances should the maximum daily dose of each be taken. This is 100mg for Sildenafil, 20mg for Tadalafil, 20mg for Vardenafil, and 200mg for Avanafil.

Long-term therapy with Tadalafil 5 mg

Tadalafil is suitable in low doses for long-term therapy. With the daily intake of Tadalafil 5 mg, the active ingredient level in the blood is kept constant. The result: Spontaneous erections are possible again with sexual arousal.

Some PDE-5 inhibitors, such as sildenafil, are used in another area: erectile tissue exercise. In this case, the active ingredient is taken in a low dose every day before going to bed. This is supposed to counteract the degeneration of the erectile tissue. Successful therapy manifests itself after a few months through the famous morning latte and increased libido.

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