Lekap (Sildenafil)

Sildenafil acts on the nitric‑oxide/cGMP pathway to improve vascular function in specific conditions.

• Erectile dysfunction: enhances the ability to achieve and maintain an erection suitable for sexual activity.
• Pulmonary arterial hypertension: lowers pulmonary arterial pressure and improves exercise capacity.
• Male sexual dysfunction related to vascular insufficiency: supports satisfactory sexual performance.

• Sildenafil selectively inhibits phosphodiesterase type 5 (PDE5), the enzyme that degrades cyclic guanosine monophosphate (cGMP) in smooth muscle cells. By preventing cGMP breakdown, it prolongs smooth‑muscle relaxation in the corpus cavernosum and pulmonary vasculature, facilitating increased blood flow in response to nitric‑oxide signaling.

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

Common Side Effects

• Headache: mild to moderate pain often resolving within a few hours.
• Flushing: warmth and redness of the face or upper chest.
• Dyspepsia: indigestion or upset stomach.
• Nasal congestion: blocked or runny nose.
• Visual disturbances: blurred vision or color tinge.
• 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 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: marked drop in blood pressure causing dizziness or fainting.
• Allergic reaction: rash, itching, swelling, or difficulty breathing.

Before initiating therapy, consider the following safety measures.

• Cardiovascular assessment: evaluate for recent heart attack, unstable angina, or severe heart failure.
• Nitrate use: avoid concurrent use with any nitrate medication due to risk of profound hypotension.
• Visual disorders: discontinue if sudden vision loss or eye pain occurs.
• Hearing disorders: monitor for sudden hearing changes and seek medical attention if noted.
• Hepatic or renal impairment: dose adjustment may be required in severe dysfunction.
• Store at room temperature: keep in the original packaging, protect from moisture and direct sunlight.

Sildenafil can interact with several drug classes; awareness helps prevent adverse events.

Major Interactions (Avoid)

• Nitrates: concurrent use can cause dangerous drops in blood pressure.
• Guanylate cyclase stimulators (e.g., riociguat): additive vasodilatory effect may lead to severe hypotension.
• Alpha‑blockers: combined effect may result in marked blood pressure reduction.

Moderate Interactions (Monitor Closely)

• CYP3A4 inhibitors (e.g., erythromycin, ketoconazole): may increase sildenafil plasma levels.
• Antihypertensive agents: additive blood pressure‑lowering effect requires monitoring.