Guidelines for Initiating Viagra (Sildenafil) Therapy in Patients with Erectile Dysfunction
Sildenafil (Viagra) is recommended as a first-line therapy for erectile dysfunction (ED) due to its proven efficacy and acceptable safety profile when used appropriately. 1
Initial Assessment and Dosing
- Oral phosphodiesterase type 5 inhibitors (PDE5i) like sildenafil should be offered as first-line therapy for erectile dysfunction unless contraindicated 1
- The recommended starting dose of sildenafil for ED is 50 mg taken approximately 1 hour before sexual activity, with dose adjustments based on efficacy and tolerability 1
- Dosing should be titrated to provide optimal efficacy while minimizing adverse effects - doses can be adjusted up to 100 mg or down to 25 mg 1
- Sildenafil should not be taken more than once daily 2
Patient Education for Proper Use
- Instruct patients that sexual stimulation is necessary for the medication to be effective 1
- Multiple trials may be required to establish efficacy - patients should try the medication several times before determining it doesn't work 1
- Taking sildenafil with a large meal may reduce effectiveness and delay onset of action 1
- The medication should be taken approximately 1 hour before anticipated sexual activity 3
Contraindications and Precautions
- Sildenafil is absolutely contraindicated in patients taking nitrate medications (e.g., nitroglycerin, isosorbide mononitrate/dinitrate) due to risk of severe hypotension 2, 4
- Use caution in patients with recent myocardial infarction or stroke (within 6 months), unstable angina, or cardiac failure 4
- Patients with cardiovascular disease should be stratified according to risk:
- High-risk patients (unstable/refractory angina, uncontrolled hypertension, CHF class II+, MI/stroke within 2 weeks) should not receive treatment until cardiac condition stabilizes 1
- Low-risk patients (asymptomatic CAD with <3 risk factors, controlled hypertension, mild stable angina, successful revascularization) may be considered for treatment 1
- Intermediate-risk patients should undergo cardiac evaluation before treatment 1
Special Populations
- In patients with mild to moderate hepatic or renal impairment, start with lower doses due to potential for delayed metabolism 1
- Sildenafil is generally not recommended in patients with severe renal or liver disease 1
- Men with diabetes and post-prostatectomy patients typically have more severe ED at baseline and may respond less robustly to PDE5i therapy 1
- In men with ED and testosterone deficiency, combining testosterone therapy with sildenafil may be more effective than sildenafil alone 1
Common Side Effects
- The most common adverse effects include headache (11%), dyspepsia (9%), flushing, nasal congestion, myalgia, and visual disturbances 3, 5
- Most adverse events are mild to moderate in nature and dose-dependent 1
- The incidence of serious cardiovascular adverse events is low and comparable to placebo when used in appropriate patients 3
Monitoring and Follow-up
- Titrate dose based on patient and partner reports of efficacy, side effects, and acceptance of therapy 1
- For patients who don't respond to sildenafil alone, consider combination with other therapies (e.g., psychotherapy) which may provide greater improvements in erectile function 1
- If sildenafil is ineffective after multiple properly administered attempts at the maximum tolerated dose, consider alternative ED treatments 1
Important Clinical Pitfalls to Avoid
- Failing to screen for contraindications, especially concurrent nitrate use, which can lead to dangerous hypotension 2, 4
- Not providing adequate instructions on proper use, leading to perceived treatment failures 1
- Overlooking the opportunity to assess cardiovascular risk factors, as ED may be an early marker of cardiovascular disease 1
- Not considering testosterone deficiency in men with suboptimal response to sildenafil 1
- Starting with too high a dose in elderly patients or those with renal/hepatic impairment, increasing the risk of adverse effects 1