Sildenafil

Generic name: sildenafil (oral) [ sil-DEN-a-fil ]

Brand names: Revatio, Viagra

Drug classes: Agents for pulmonary hypertension, Impotence agents

Dosage Forms: Tablet

Route of Administration: Oral

Dose: 25 mg, 50 mg, 100 mg (Viagra); 20 mg (Revatio)

Mechanism of Action: Sildenafil is a phosphodiesterase type-5 (PDE5) inhibitor that works by increasing blood flow to specific areas of the body. In erectile dysfunction (ED), it relaxes the smooth muscle in the corpus cavernosum of the penis, allowing increased blood flow and causing an erection in response to sexual stimulation. In pulmonary arterial hypertension (PAH), sildenafil relaxes blood vessels in the lungs, reducing pulmonary blood pressure.

Drug Usage Cases: Sildenafil (Viagra) is used to treat erectile dysfunction (ED) in men by helping them achieve and maintain an erection. Sildenafil (Revatio) is used to treat pulmonary arterial hypertension (PAH) by improving exercise capacity and delaying clinical worsening. These medications should be used under medical supervision and are not intended for use by women or children.

Drug Contraindications: Sildenafil is contraindicated in patients using nitrates (such as nitroglycerin) or guanylate cyclase stimulators (such as riociguat) due to the risk of a significant drop in blood pressure. It is also contraindicated in patients with a known hypersensitivity to sildenafil or any of its components. Patients with severe cardiovascular disorders, recent history of stroke or myocardial infarction, severe liver impairment, or certain rare inherited eye diseases should avoid sildenafil.

Side Effects: Common side effects may include headache, flushing, upset stomach, nasal congestion, dizziness, and visual disturbances (such as changes in color vision, blurred vision). Serious side effects that require immediate medical attention include: Sudden vision loss in one or both eyes (non-arteritic anterior ischemic optic neuropathy, or NAION). Sudden hearing loss or ringing in the ears. Chest pain, irregular heartbeat, or shortness of breath. Prolonged erection lasting more than 4 hours (priapism). Signs of an allergic reaction (rash, itching, swelling of the face or throat, difficulty breathing)

Warnings: Sildenafil should not be used with nitrates or certain medications used to treat heart conditions and high blood pressure, as this combination can cause a dangerous drop in blood pressure. It should be used cautiously in patients with cardiovascular disease, low blood pressure, severe dehydration, or anatomical deformities of the penis. Patients should avoid excessive alcohol consumption as it may increase the risk of side effects. If an erection lasts more than 4 hours, seek immediate medical attention to prevent permanent damage (priapism).

Use During Pregnancy or Breastfeeding: Sildenafil is not indicated for use in women. Its safety and efficacy during pregnancy or breastfeeding have not been established. Women who are pregnant or breastfeeding should consult their healthcare provider before using any medication.