Mexon (Sildenafil)

Sildenafil is a phosphodiesterase type 5 inhibitor used to manage vascular‑related conditions.

• Erectile dysfunction: improves the ability to achieve and maintain an erection suitable for sexual activity.
• Pulmonary arterial hypertension: lowers pulmonary arterial pressure and enhances exercise capacity in patients with PAH.

• Sildenafil selectively inhibits the enzyme phosphodiesterase type 5, preventing the breakdown of cyclic guanosine monophosphate (cGMP). Elevated cGMP levels lead to relaxation of smooth muscle in the corpus cavernosum and pulmonary vasculature, facilitating increased blood flow and improved erectile function or reduced pulmonary arterial pressure.

Sildenafil may cause a range of adverse reactions, most of which are mild and transient.

Common Side Effects

• Headache: mild to moderate headache often occurring shortly after dosing.
• Flushing: warmth and redness of the face or upper chest.
• Dyspepsia: indigestion or upset stomach.
• Nasal congestion: stuffy or runny nose.
• Visual disturbances: blurred vision or a blue‑tinted visual field.
• Back pain: muscle aches, typically in the lower back.

Serious or Rare Side Effects

• Priapism: prolonged erection lasting more than four hours, requiring emergency care.
• Sudden hearing loss: abrupt decrease or loss of hearing.
• Myocardial infarction: heart attack, especially in patients with cardiovascular disease.
• Stroke: cerebrovascular accident presenting with neurological deficits.
• Severe hypotension: dangerous drop in blood pressure, potentially causing dizziness or fainting.
• Vision loss: rare cases of non‑arteritic anterior ischemic optic neuropathy.

Before prescribing or dispensing Mexon, consider the following safety measures.

• Cardiovascular assessment: evaluate recent cardiac events or unstable angina.
• Concomitant nitrate use: avoid due to risk of profound hypotension.
• Visual disorders: use caution in patients with retinal diseases such as retinitis pigmentosa.
• Hypotension risk: monitor blood pressure, especially in patients on antihypertensives.
• Drug interactions: review all concomitant medications for potential interactions.
• Store at below 25°C: keep in the original packaging, protect from moisture and direct sunlight.

Sildenafil can interact with several medicines, requiring careful management.

Major Interactions (Avoid)

• Nitrates (e.g., nitroglycerin): may cause severe hypotension.
• Guanylate cyclase stimulators (e.g., riociguat): additive blood‑pressure‑lowering effect.
• Alpha‑blockers (e.g., doxazosin): can lead to marked hypotension.

Moderate Interactions (Monitor Closely)

• Strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole): increase sildenafil plasma concentrations.
• CYP3A4 inducers (e.g., rifampicin, carbamazepine): reduce sildenafil effectiveness.
• Antihypertensive agents: may enhance blood‑pressure‑lowering actions, requiring dose adjustments.