Step 1—oral agents
	Sildenafil (Viagra): 25, 50 or 100 mg orally 1 hour before coitus (usual initial dose is 50 mg)*
	Investigational agents (e.g., L-arginine)
Step 2—vacuum or constriction devices
Step 3—penile therapies
	Intracavernosal injections: prostaglandin E (alprostadil [Caverject, Prostin VR]), paperverine (Pavabid), phentolamine (Regitine)
	Intraurethral insertion: prostaglandin E (alprostadil [Muse])
Step 4—penile surgery
	Penile prostheses: semirigid or malleable rod, hydraulic inflatable device
	Penile vascular surgery