Oximun (Sildenafil Citrate)

Sildenafil citrate acts on the nitric‑oxide/cGMP pathway to improve vascular smooth‑muscle relaxation in several conditions.

• 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 Raynaud's phenomenon: may reduce frequency of vasospastic attacks in affected limbs.

• Sildenafil citrate selectively inhibits phosphodiesterase type 5, the enzyme responsible for breaking down cyclic guanosine monophosphate (cGMP) in smooth‑muscle cells. By preventing cGMP degradation, intracellular levels rise, leading to prolonged smooth‑muscle relaxation and vasodilation in the corpus cavernosum and pulmonary vasculature, which underlies its therapeutic effects.

Adverse reactions to sildenafil citrate vary in frequency and severity.

Common Side Effects

• Headache: mild to moderate intensity.
• Flushing: warmth and redness, typically transient.
• Dyspepsia: occasional stomach discomfort or indigestion.
• Nasal congestion: feeling of a blocked nose.
• Visual disturbances: blurred vision or altered colour perception.
• Myalgia: mild muscle aches.

Serious or Rare Side Effects

• Priapism: prolonged erection lasting more than four hours, requiring urgent care.
• Sudden hearing loss: abrupt decrease or loss of hearing.
• Severe hypotension: marked drop in blood pressure, especially with nitrates.
• Cardiac arrhythmias: irregular heart rhythms in susceptible individuals.
• Allergic reactions: rash, itching, swelling, or anaphylaxis.
• Vision loss: sudden loss of vision in one or both eyes.

When prescribing sildenafil citrate, clinicians should consider several safety aspects.

• Cardiovascular assessment: evaluate for recent cardiac events or unstable angina before use.
• Concomitant nitrate therapy: avoid due to risk of severe hypotension.
• Visual disorders: use caution in patients with retinal disease.
• Hepatic or renal impairment: dose adjustment may be required.
• Age considerations: older adults may be more sensitive to blood‑pressure effects.
• Store at ambient temperature: keep below 25 °C, in the original packaging, protected from moisture.

Sildenafil citrate can interact with several medication classes, requiring attention to avoid adverse outcomes.

Major Interactions (Avoid)

• Nitrates: concurrent use can cause profound hypotension.
• Guanylate cyclase stimulators: additive vasodilatory effect may lead to dangerous blood‑pressure drops.

Moderate Interactions (Monitor Closely)

• Alpha‑blockers: may enhance hypotensive response, especially during initial dosing.
• CYP3A4 inhibitors (e.g., ketoconazole, erythromycin): increase sildenafil plasma levels.
• CYP3A4 inducers (e.g., rifampicin, carbamazepine): reduce sildenafil exposure.
• Antihypertensive agents: may require blood‑pressure monitoring.
• Alcohol: excessive intake can potentiate hypotensive effects.