Sildenafil|Viagra|Structure|Synthesis|Mechanism of action|Uses|Doses|Side-effects

  

 Sildenafil

Sildenafil is a erectile dysfunction drug and a vasodilator, which is used in the treatment of male sexual function problems. It is a pyrazolopyrimidinone derivative. It is a white to off-white crystalline solid, which is soluble in water at 25°C temperature. It is also known as" VIAGRA". The molecular weight of sildenafil is, 474.6 gm/mol and the melting point is, 190°C.

Structure:

The molecular formula of Sildenafil is [C­­­­­22H30N6 O4S].

The IUPAC name of sildenafil is,5-[2-ethoxy-5-(4-methylpiperazin-1-yl)sulfonylphenyl]-1-methyl-3-propyl-6H-pyrazolo[4,3-d]pyrimidin-7-one.

Synthesis:

Mechanism of action:

First we discussed about the physiological process of erection of the penis. This process involves the release of nitric oxide (NO) in the corpus cavernosum during sexual stimulation. This nitric oxide (NO) is responsible for the activation of the granulate cyclase enzyme, which increase the cGMP level, producing smooth muscle relaxation and allow the blood flow in the penis. It enhanced the effect of nitric oxide (NO) by inhibiting PDE5 (Phosphodiestarase type5). This  PDE5 (Phosphodiestarase type5) is responsible for the degradation of cGMP in the corpus cavernosum. When sexual stimulation causes local release of nitric oxide (NO) occur by inhibiting  PDE5 (Phosphodiestarase type5), resulting in smooth muscle relaxation and increase blood flow in the corpus cavernosum.

Dose:

• The usual adult dose for erectile dysfunction is 50mg, approximately 30 min to 1 hour before sexual activity.
• For the treatment of  pulmonary arterial hypertension the usual adult dose is 20mg orally three times daily.

Uses:

• Sildenafil is used in the treatment of male sexual problems like erectile dysfunction, it relax the smooth muscle, which is present in penis and increased the flow of blood in the penis.
• It is also used in the treatment of pulmonary arterial hypertension.

Side-effects:

The overdose of sildenafil shows different types of side effects like,

1. Stomach upset
2. Irregular heartbeat
3. Flushing
4. Blurred vision
5. Dizziness
6. Headache
7. Erection is painful or last longer than 4 hours
8. Chest pain