Maxon Active (Sildenafil)

Sildenafil acts on the nitric‑oxide/cGMP pathway to improve vascular smooth‑muscle relaxation in specific disease states.

• Erectile dysfunction: enhances the ability to achieve and maintain an erection during sexual stimulation.
• Pulmonary arterial hypertension: improves exercise capacity and delays clinical worsening by lowering pulmonary vascular resistance.

• Sildenafil selectively inhibits phosphodiesterase type 5 (PDE5), the enzyme responsible for degrading cyclic guanosine monophosphate (cGMP) in the corpus cavernosum and pulmonary vasculature. By preventing cGMP breakdown, it prolongs smooth‑muscle relaxation, increases blood flow to the penis during sexual arousal and reduces pulmonary arterial pressure in hypertension.

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

Common Side Effects

• Headache: mild to moderate pain often occurring within hours of 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: muscular discomfort, typically after several hours.

Serious or Rare Side Effects

• Priapism: prolonged erection lasting more than four hours, requiring urgent medical care.
• Sudden vision loss: non‑arteritic anterior ischemic optic neuropathy.
• Sudden hearing loss: unexplained decrease in hearing acuity.
• Myocardial infarction: heart attack, especially in patients with pre‑existing cardiovascular disease.
• Stroke: cerebrovascular accident, particularly in high‑risk individuals.
• Severe hypotension: marked drop in blood pressure, potentially leading to fainting.

Before initiating therapy, clinicians should evaluate cardiovascular status and review concomitant medications.

• Cardiovascular assessment: ensure patient can tolerate sexual activity without undue risk.
• Nitrate use: avoid concurrent use with nitrates or nitric‑oxide donors.
• Alpha‑blocker co‑administration: use caution and monitor blood pressure.
• Hepatic/renal function: adjust dosing in severe impairment.
• Patient counseling: advise on timing of sexual activity relative to dose.
• Store at below 25°C: keep in the original pack, protect from moisture.

Sildenafil interacts with several drug classes that can alter its efficacy or safety.

Major Interactions (Avoid)

• Nitrates (e.g., nitroglycerin): may cause severe hypotension.
• Nitric‑oxide donors (e.g., amyl nitrite): risk of dangerous blood‑pressure drop.
• Guanylate cyclase stimulators (e.g., riociguat): additive vasodilatory effect.
• Certain protease inhibitors (e.g., ritonavir): can markedly increase sildenafil levels.
• Uncontrolled hypertension medications: may exacerbate blood‑pressure changes.

Moderate Interactions (Monitor Closely)

• Alpha‑blockers: may cause additive hypotensive effect.
• Antihypertensives (e.g., beta‑blockers): monitor for excessive blood‑pressure reduction.
• Strong CYP3A4 inhibitors (e.g., ketoconazole): increase plasma concentration.
• CYP3A4 inducers (e.g., rifampin): reduce effectiveness.
• Other PDE5 inhibitors: avoid concurrent use to prevent toxicity.