As we reported more than a year ago in our February 2010 LMR review — Managing Erectile Dysfunction — When Viagra Doesn’t  — phosphodiasterase-5 (PDE-5) inhibitors, e.g., sildenafil (Viagra), vardenafil (Levitra), and tadalafil (Cialis), are ineffective in 30-40% of men diagnosed with erectile dysfunction (ED).  Why? Because the PDE-5 inhibitors help restore erectile function by … Continue reading L-Citrulline: Restoring Erectile Function (Viagra Doesn’t)