Olvion (Sildenafil)

Sildenafil acts on the nitric‑oxide/cGMP pathway to facilitate erection in men with erectile dysfunction.

• Erectile dysfunction: improves ability to achieve and maintain an erection suitable for sexual activity.
• Pulmonary arterial hypertension: lowers pulmonary arterial pressure and improves exercise capacity.
• Secondary use in benign prostatic hyperplasia (off‑label): may relieve lower urinary tract symptoms associated with BPH.

• Sildenafil selectively inhibits the enzyme phosphodiesterase type 5, preventing the breakdown of cyclic guanosine monophosphate (cGMP) in smooth‑muscle cells. Elevated cGMP levels lead to relaxation of vascular smooth muscle in the corpus cavernosum and pulmonary vasculature, enhancing blood flow when sexual stimulation or pulmonary vasoconstriction is present.

Adverse reactions to sildenafil are reported across a range of severity.

Common Side Effects

• Headache: mild to moderate headache occurring shortly after dosing.
• Flushing: warmth and redness, typically on the face or neck.
• Dyspepsia: indigestion or upset stomach.
• Nasal congestion: stuffy nose without infection.
• Visual disturbances: blurred vision or changes in colour perception.
• Myalgia: muscle aches, often in the back or limbs.

Serious or Rare Side Effects

• Priapism: prolonged erection lasting more than four hours, requiring urgent medical attention.
• Sudden vision loss: abrupt loss of vision in one or both eyes (non‑arteritic anterior ischemic optic neuropathy).
• Sudden hearing loss: unexplained decrease or loss of hearing.
• Severe hypotension: marked drop in blood pressure, especially when combined with nitrates.
• Cardiovascular events: chest pain, myocardial infarction, or stroke in high‑risk patients.
• Allergic reactions: rash, itching, swelling, or anaphylaxis.

Before prescribing sildenafil, clinicians should assess patient history and comorbid conditions.

• Cardiovascular assessment: evaluate for recent myocardial infarction, unstable angina, or severe heart failure.
• Nitrate use: avoid co‑administration with nitrates or nitric‑oxide donors.
• Concomitant medications: review for drugs that may potentiate hypotensive effects.
• Visual or auditory disorders: caution in patients with pre‑existing eye or ear conditions.
• Renal or hepatic impairment: dose adjustment may be required based on organ function.
• Store at below 25°C: keep in the original container, protect from moisture and direct sunlight.

Sildenafil may interact with several drug classes, altering its efficacy or safety profile.

Major Interactions (Avoid)

• Nitrates: concurrent use can cause severe hypotension.
• Guanylate cyclase stimulators: additive vasodilatory effect leading to dangerous blood pressure drops.
• Certain antifungal agents (e.g., ketoconazole): increase sildenafil plasma concentrations.

Moderate Interactions (Monitor Closely)

• Alpha‑blockers: may cause additive blood pressure reduction.
• Antihypertensives: monitor for enhanced hypotensive response.
• CYP3A4 inhibitors/inducers: may require dose adjustment based on plasma level changes.