... ) selective inhibitor, penile smooth muscle relaxation allows rapid erection. Sildenafil is cheap, is the development and production of low-cost ... ) 98319-26-7 Dutasteride (Avodart) 164656-23-9 Sildenafil Citrate 171599-83-0 Sildenafil (Viagra) 139755-83-2 Tadalafil (Cialis) 171596-29 ... 129938-20-1 Exemestane 107868-30-4 Clomifene Citrate 50-41-9 Tamoxifen Citrate 54965-24-1 Letrozole (Femara) 112809-51 ...