Tadadel 20 mg likely refers to Tadalafil 20 mg.

1. Pharmacological action

- Tadalafil is a phosphodiesterase - 5 (PDE - 5) inhibitor. It works by inhibiting the PDE - 5 enzyme, which is responsible for the degradation of cyclic guanosine monophosphate (cGMP) in the smooth muscle cells of the corpus cavernosum in the penis (in men) and in the clitoris and vaginal smooth muscle (in women). By inhibiting PDE - 5, tadalafil increases cGMP levels, leading to smooth muscle relaxation and increased blood flow, which helps in achieving and maintaining an erection in men with erectile dysfunction and can also have effects on sexual function in women.

2. Usage

For erectile dysfunction in men:

- The usual starting dose may be 10 mg, but in some cases, a 20 - mg dose can be used as prescribed by a healthcare provider. It should be taken before anticipated sexual activity. However, it is not recommended to take more than one dose per day.

For pulmonary arterial hypertension:

- Tadalafil is also used to treat pulmonary arterial hypertension (PAH) at different doses, but the dosing regimen for this indication is carefully managed in the context of overall treatment for the complex condition of PAH.

3. Precautions and side effects

Precautions:

- It should not be used in combination with nitrates (e.g., nitroglycerin) as this can cause a dangerous drop in blood pressure.

- People with certain cardiovascular conditions, liver or kidney problems may require dose adjustments or special monitoring.

Side effects:

- Common side effects may include headache, flushing, indigestion, nasal congestion, back pain, and muscle aches. In rare cases, it may cause more serious side effects such as vision changes or priapism (a prolonged and painful erection in men).