Menup (Sildenafil)

• Sildenafil, a phosphodiesterase type 5 inhibitor, is used in disorders where enhanced nitric oxide–cGMP signaling leads to vascular smooth‑muscle relaxation.
• Erectile dysfunction: improves the ability to achieve and maintain an erection sufficient for satisfactory sexual intercourse by increasing penile arterial inflow and reducing venous outflow.
• Pulmonary arterial hypertension: reduces pulmonary arterial pressure and vascular resistance, leading to improved exercise tolerance and functional class in patients with WHO Group 1 pulmonary hypertension.

• Sildenafil selectively inhibits the enzyme phosphodiesterase type 5, which degrades cyclic guanosine monophosphate (cGMP) in smooth‑muscle cells. By blocking PDE5, intracellular cGMP accumulates, promoting relaxation of vascular smooth muscle and vasodilation in the corpus cavernosum and pulmonary arteries, thereby facilitating increased blood flow to these tissues. The effect is activity‑dependent, occurring primarily where nitric oxide has been released, and it does not significantly affect other phosphodiesterase isoforms, preserving cardiac contractility and systemic blood pressure in most patients.

Sildenafil may cause a range of adverse reactions, varying from mild to serious.

Common Side Effects

• Headache: mild to moderate pain often occurring shortly after dosing.
• Flushing: warmth and redness of the face or upper body.
• Indigestion: discomfort or a feeling of fullness in the stomach.
• Nasal congestion: blocked or runny nose.

Serious or Rare Side Effects

• Priapism: prolonged erection lasting more than four hours, requiring medical attention.
• Sudden loss of vision: abrupt visual impairment, possibly indicating non‑arteritic anterior ischemic optic neuropathy.
• Sudden loss of hearing: rapid decrease in hearing acuity, sometimes accompanied by tinnitus.

• Before prescribing sildenafil, clinicians should evaluate several safety considerations to minimize risks.
• Assess cardiovascular status: ensure the patient can tolerate sexual activity without undue cardiac strain.
• Avoid use with nitrates: concurrent use may cause severe hypotension.
• Use caution in hepatic impairment: dose adjustment may be needed for reduced metabolism.
• Monitor for visual changes: discontinue if sudden loss of vision occurs.
• Store at ambient temperature below 25°C: keep in the original pack, protect from moisture.

Sildenafil can interact with other medicines, altering its effectiveness or increasing adverse effects.

Major Interactions (Avoid)

• Nitrates (e.g., nitroglycerin): may cause severe hypotension.
• Nitric oxide donors (e.g., isosorbide dinitrate): risk of dangerous blood pressure drop.
• Protease inhibitors (e.g., ritonavir): increase sildenafil plasma levels, raising toxicity risk.

Moderate Interactions (Monitor Closely)

• Alpha‑blockers (e.g., doxazosin): may enhance hypotensive effect.
• Strong CYP3A4 inhibitors (e.g., erythromycin): may raise sildenafil concentrations.