Licosil (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 sufficient for sexual activity.
• Pulmonary arterial hypertension: improves exercise capacity and reduces pulmonary vascular resistance in patients with PAH.

• Sildenafil selectively inhibits phosphodiesterase type 5 enzymes, 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 the physiological responses required for erection and reduced pulmonary arterial pressure.

Adverse reactions may occur with sildenafil use and are categorized by frequency and severity.

Common Side Effects

• Headache
• Flushing
• Dyspepsia
• Nasal congestion
• Visual disturbance (e.g., blurred vision)
• Back pain

Serious or Rare Side Effects

• Priapism (prolonged erection)
• Sudden loss of vision (non‑arteritic anterior ischemic optic neuropathy)
• Sudden hearing loss
• Myocardial infarction
• Stroke
• Severe hypotension

Before prescribing sildenafil, clinicians should evaluate patient-specific risk factors and provide appropriate counseling.

• Cardiovascular assessment: ensure patient can tolerate sexual activity.
• Nitrate use: avoid concurrent administration due to risk of profound hypotension.
• Alpha‑blocker therapy: use with caution and monitor blood pressure.
• Visual changes: advise patients to report sudden vision loss promptly.
• Storage: Store at room temperature: keep in the original container, protect from moisture and direct sunlight.

Sildenafil may interact with several drug classes, requiring careful review of patient medication lists.

Major Interactions (Avoid)

• Nitrates (e.g., nitroglycerin) – risk of severe hypotension.
• Guanylate cyclase stimulators (e.g., riociguat) – additive vasodilatory effect.
• Certain protease inhibitors (e.g., ritonavir) – may markedly increase sildenafil levels.

Moderate Interactions (Monitor Closely)

• Strong CYP3A4 inhibitors (e.g., ketoconazole) – may raise plasma concentrations.
• CYP3A4 inducers (e.g., rifampin) – may reduce efficacy.
• Antihypertensive agents – monitor for additive blood‑pressure lowering effects.