Sildenafil (Intravenous)

Generic name: Sildenafil

Drug class: Phosphodiesterase type 5 (PDE5) inhibitor

Dosage form: Intravenous solution

Root of administration: Intravenous

Dose:

• For erectile dysfunction: 50 mg administered intravenously once daily, adjusted based on efficacy and tolerability.
• For pulmonary arterial hypertension: 10 mg administered intravenously three times daily, adjusted based on clinical response and tolerability.

Mechanism of action: Sildenafil inhibits the enzyme phosphodiesterase type 5 (PDE5), leading to increased levels of cyclic guanosine monophosphate (cGMP) in smooth muscle cells. Elevated cGMP levels result in vasodilation and increased blood flow to specific tissues, such as the corpus cavernosum in the penis and pulmonary vasculature, thereby improving erectile function and reducing pulmonary vascular resistance.

Drug usage cases:

• Treatment of erectile dysfunction in adult men
• Management of pulmonary arterial hypertension in adults
• Off-label use for Raynaud’s phenomenon
• Off-label use for altitude sickness prevention

Drug contraindications:

• Concurrent use with nitrates or nitric oxide donors
• Severe hepatic impairment
• Severe hypotension (systolic blood pressure < 90 mmHg)
• Hypersensitivity to sildenafil or any component of the formulation

Side effects:

• Headache
• Flushing
• Dyspepsia
• Visual disturbances (e.g., blurred vision, color tinge)
• Priapism (prolonged erection) in rare cases
• Hypotension
• Syncope
• Chest pain
• Palpitations
• Rash
• Gastrointestinal discomfort
• Back pain
• Myalgia
• Flu-like symptoms

Warnings:

• Use with caution in patients with cardiovascular disease, especially those with a history of myocardial infarction, stroke, or life-threatening arrhythmia within the past 6 months.
• Monitor blood pressure regularly during treatment.
• Discontinue use and seek immediate medical attention if an erection lasts longer than 4 hours (priapism).
• Not recommended for use in women.
• Use with caution in patients with a history of peptic ulcer disease or bleeding disorders.
• May cause dizziness; caution when driving or operating heavy machinery.
• Alcohol may enhance the hypotensive effect; limit alcohol intake during treatment.

Use during pregnancy or breastfeeding:

Sildenafil is not approved for use in women and should not be used during pregnancy or breastfeeding. There is limited data on the safety of sildenafil in pregnant or lactating women. Animal studies have shown potential risks, and its use in these populations is not recommended due to the lack of sufficient safety data. If a woman becomes pregnant while taking sildenafil, she should consult her healthcare provider to discuss potential risks and benefits.