What is the recommended dosing regimen for Viagra (sildenafil)?

Viagra (Sildenafil) Dosing Recommendations

For erectile dysfunction, the recommended starting dose of sildenafil is 50 mg taken approximately one hour before sexual activity, with a dose range of 25-100 mg based on efficacy and tolerability. 1, 2

Initial Dosing and Titration

• The standard starting dose for most men is 50 mg taken as needed, approximately 1 hour before anticipated sexual activity 2
• Dose can be adjusted based on efficacy and tolerability:
  • May be increased to 100 mg for improved efficacy if 50 mg is insufficient 1, 3
  • May be decreased to 25 mg if side effects occur at higher doses 2
• Sildenafil should not be taken more than once daily 2, 4

Special Population Considerations

• Lower starting doses (25 mg) are recommended for:
  • Elderly patients (≥65 years) 2
  • Patients with hepatic or renal impairment 1, 2
  • Patients taking CYP3A4 inhibitors (e.g., ritonavir, saquinavir, ketoconazole, erythromycin, cimetidine) 2, 4

Administration Guidelines

• Take sildenafil approximately 1 hour before sexual activity 2
• Efficacy may last up to 4-5 hours, with some effect potentially lasting up to 10 hours 5, 6
• Sildenafil can be taken with or without food, though high-fat meals may slightly delay absorption 5
• Sexual stimulation is required for sildenafil to be effective 2

Contraindications

• Concurrent use with nitrates or nitric oxide donors is absolutely contraindicated due to risk of severe hypotension 7, 4
• Use caution in patients with cardiovascular disease, following physician prescribing guidelines from ACC/AHA 4

Efficacy Considerations

• Approximately 69% of men report improved erections with sildenafil versus 35.5% with placebo 1, 8
• Dose-related improvements in erectile function have been observed (50 mg vs. 25 mg shows improved efficacy) 1, 8
• The 100 mg dose may provide additional benefits in reducing anxiety about sexual performance compared to 50 mg 3
• Long-term efficacy is maintained with continued use 6

Common Side Effects

• Most common side effects are mild to moderate and include headache, flushing, dyspepsia, nasal congestion, and abnormal vision 2, 3
• Side effects are typically transient and dose-related 2

Monitoring and Follow-up

• Periodic follow-up is recommended to assess efficacy, side effects, and any significant changes in health status or medications 1
• If initial treatment fails, evaluate whether the trial was adequate (proper timing, sexual stimulation, maximum dosing) before considering alternative treatments 1

Remember that sildenafil should be prescribed only after appropriate evaluation of erectile dysfunction and consideration of contraindications, particularly concurrent use of nitrates.