Tadalafil es un fármaco. A continuación se detallan sus principales características:，Tadalafil: Principales características de un fármaco

1. Classification and Mechanism of Action

Classification: It is a selective inhibitor of phosphodiesterase type 5 (PDE - 5).

Mechanism of Action:

- In the human body, the enzyme PDE - 5 is responsible for degrading nitric oxide (NO) - dependent cyclic GMP (cyclic guanosine monophosphate).

- Tadalafil inhibits PDE - 5, allowing the levels of cGMP to remain elevated. In the vascular and smooth muscle tissues of the penis, an increase in cGMP levels causes muscle relaxation and an increase in blood flow, which is crucial for achieving and maintaining an erection.

2. Therapeutic Indications

Erectile Dysfunction: This is the main indication. It helps men who have difficulties in obtaining or maintaining an erection sufficient for sexual activity.

Pulmonary Hypertension: It is also used in the treatment of pulmonary hypertension. Since it relaxes the vascular muscles in the lungs, it can improve pulmonary hemodynamics.

3. Dosage and Administration

Variable Dosage:

- In the case of erectile dysfunction, the recommended dose is usually 10 mg, which can be adjusted according to individual efficacy and tolerance, and can be 5 mg or 20 mg.

- In pulmonary hypertension, the dose is different and is adjusted according to the patient's condition.

Administration Method: It is generally administered orally and is relatively rapidly absorbed, with an onset of action occurring approximately between 30 minutes and 2 hours after ingestion.

4. Side Effects

Common:

- Headache is one of the most common side effects and may occur in a significant proportion of patients.

- Abdominal pain, stomach acidity, and nasal congestion are other relatively frequent side effects.

Uncommon but Serious:

- There may be changes in vision, such as blue - tinted vision (cyanopsia), although this is an uncommon side effect.

- There is also a risk, although very low, of adverse cardiovascular events. Therefore, caution should be exercised in patients with a history of cardiovascular diseases.

Tadalafil functions by inhibiting the action of an enzyme called phosphodiesterase - 5 (PDE - 5). This enzyme typically breaks down a substance known as cyclic guanosine monophosphate (cGMP), and cGMP plays a role in relaxing blood vessels and increasing blood flow in the corpus cavernosum of the penis. When PDE - 5 is inhibited, the level of cGMP rises, leading to the dilation of blood vessels in the corpus cavernosum, increasing blood inflow, and thus helping men achieve and maintain an erection.

Tadalafil is usually available in the form of oral tablets and can be taken 30 minutes to 1 hour before sexual activity is required. Unlike some other PDE - 5 inhibitors, the effect of tadalafil can last up to 36 hours, which is why it is sometimes referred to as the "weekend pill". Even with this long - lasting effect, sexual stimulation is still required for the drug to take effect.

It should be noted that tadalafil is not suitable for everyone. Before using it, one should consult a doctor, especially for those with heart problems, hypotension, certain eye diseases, or other health issues. It should not be used simultaneously with nitrate drugs because this may lead to a severe drop in blood pressure.