Recommended Sildenafil Dosing
For erectile dysfunction, the recommended starting dose of sildenafil is 50 mg taken as needed approximately 1 hour before sexual activity, with a maximum of once daily. 1
Erectile Dysfunction Dosing
- The starting dose is typically 50 mg taken as needed approximately 1 hour before sexual activity (no more than once daily) 1
- The dose may be increased to 100 mg or decreased to 25 mg based on efficacy and tolerability 1
- Lower starting doses (25 mg) should be considered for elderly patients, those with hepatic or renal impairment, or patients taking CYP3A4 inhibitors (e.g., ritonavir, saquinavir, ketoconazole, erythromycin, cimetidine) 1, 2
- The maximum recommended dose is 100 mg once daily 1, 3
- Dose-related improvements in erectile function have been observed, with 50 mg showing improved efficacy over 25 mg, though 100 mg shows less additional benefit compared to the 50 mg dose 4
Pulmonary Arterial Hypertension Dosing
- For pulmonary arterial hypertension (PAH), the FDA-approved dose is 20 mg administered orally three times daily (TID) 5
- Doses should be administered 4-6 hours apart 5
- Clinical trials have demonstrated similar improvements in exercise capacity with doses of 20 mg, 40 mg, or 80 mg TID 6
- Treatment with doses higher than 20 mg TID is not recommended for PAH 5
Efficacy Considerations
- Sildenafil significantly improves erectile function compared to placebo, with approximately 69% of men reporting improved erections versus 35.5% with placebo 4
- In studies of men with erectile dysfunction due to diabetes, 56% reported improved erections with sildenafil compared to 10% with placebo 7
- In men with spinal cord injury, 78% of those with residual erectile function at baseline reported improved erections with sildenafil 8
- Higher doses (100 mg) have been shown to reduce anxiety about the next intercourse attempt compared to the 50 mg dose (56% vs 39%) 3
Safety and Adverse Effects
- Common adverse events include headache (11%), flushing, dyspepsia (9%), nasal congestion, and abnormal vision 1, 7
- Most side effects are transient and mild to moderate in severity 6, 1
- Sildenafil is absolutely contraindicated with nitrate medications due to the risk of severe hypotension 2
- Caution should be exercised when prescribing sildenafil to men with certain cardiovascular conditions, liver or kidney disease 2
Clinical Pearls
- Sildenafil works by selectively inhibiting phosphodiesterase type 5, allowing corpus cavernosum smooth muscle to relax and potentiating erections during sexual stimulation 1
- The drug is rapidly absorbed with peak plasma concentrations within 1 hour of administration 1
- The elimination half-life is 3-5 hours 1
- For erectile dysfunction, sildenafil should be taken approximately one hour before anticipated sexual activity 1
- Efficacy has been maintained in long-term (1-year) studies 1