Table 2.

Phosphodiesterase-5 (PDE₅) Inhibitors: Product Comparison

	Sildenafil (Viagra)	Vardenafil (Levitra)	Vardenafil ODT (Staxyn)	Tadalafil (Cialis)	Avanafil (Stendra)
Manufacturer	Pfizer	Bayer/GlaxoSmithKline	Bayer/GlaxoSmithKline	Eli Lilly	Vivus
Year of approval	1998	2003	2010	2003	2012
Usual dosage	25–100 mg/day	5–20 mg/day	10 mg/day	5–20 mg/day (as needed); 2.5–5 mg/day once daily	50–200 mg/day
Administration time	1 hour before sexual activity	1 hour before sexual activity	1 hour before sexual activity	At least 0.5 hours before sexual activity	0.5 hours before sexual activity
Time frame of efficacy	0.5–4 hours post dose	—	—	Up to 36 hours post dose	As early as 0.25 hours post dose
Dosage adjustments	Renal CrCl < 30 mL/minute: starting dose 25 mg Hepatic Hepatic impairment: starting dose 25 mg Drug Interactions Potent CYP3A4 inhibitors: starting dose 25 mg Ritonavir: maximum 25 mg/48 hours Other >65 years old: starting dose 25 mg	Renal Do not use in patients receiving hemodialysis Hepatic Moderate impairment: starting dose 5 mg; maximum 10 mg Severe impairment: do not use Drug Interactions Moderate CYP3A4 inhibitors: maximum 5 mg/24 hours Potent CYP3A4 inhibitors: maximum 2.5 mg/24 hours Ritonavir: maximum 2.5 mg / 72 hours Other ≥65 years of age: starting dose 5 mg	Renal Do not use in patients receiving hemodialysis Hepatic Moderate/severe impairment: do not use Drug Interactions Moderate/potent CYP3A4 inhibitors: do not use	As-needed use: Renal CrCl 30–50 mL/minute: starting dose 5 mg/day; maximum 10 mg/48 hours CrCl < 30 mL/minute or if patient is receiving hemodialysis: maximum 5 mg/72 hours Hepatic Mild/moderate impairment: maximum 10 mg/day Severe impairment: do not use Drug Interactions Potent CYP3A4 inhibitors: maximum 10 mg/72 hours Once-daily use: Renal CrCl <30 mL/minute or if on hemodialysis: do not use Hepatic Mild/moderate impairment: use with caution Severe impairment: do not use Drug Interactions Potent CYP3A4 inhibitors: maximum 2.5 mg/day	Renal Do not use if CrCl < 30 mL/minute or in patients receiving hemodialysis Hepatic Severe impairment: do not use Drug Interactions Moderate CYP3A4 inhibitors: maximum 50 mg/day Potent CYP3A4 inhibitors: do not use
Common adverse reactions	Headache, flushing, dyspepsia, nasal congestion, nasopharyngitis, visual abnormalities	Headache, flushing, dyspepsia, nasal congestion, nasopharyngitis, visual abnormalities	Headache, flushing, dyspepsia, nasal congestion, nasopharyngitis, visual abnormalities	Headache, flushing, dyspepsia, nasal congestion, nasopharyngitis, back pain, myalgia	Headache, flushing, dyspepsia, nasal congestion, nasopharyngitis
Time required from last dose to administration of a nitrate (e.g., nitroglycerin)	24 hours	24 hours	24 hours	48 hours	12 hours
AWP unit cost	$22.49 (100 mg)	$21.46 (20 mg)	$13.98 (10 mg)	$24.48 (20 mg)	—

AWP = average wholesale price; CrCl = creatinine clearance; CYP = cytochrome P450.

Data from prescribing information for sildenafil;⁸ vardenafil;⁹ tadalafil;¹⁰ avanafil;¹¹ vardenafil ODT;¹² and Red Book Online.³⁶