title: Viagra, Levitra, and Cialis: what's the difference?
authors.forename: Dawn
authors.initials: D
authors.lastname: Whitehill
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D002243:Carbolines / Q000008:administration & dosage / Q000627:therapeutic use*; D000075202:Contraindications; D004347:Drug Interactions; D007172:Erectile Dysfunction / Q000188:drug therapy*; D006801:Humans; D007093:Imidazoles / Q000008:administration & dosage / Q000627:therapeutic use*; D008297:Male; D010726:Phosphodiesterase Inhibitors / Q000008:administration & dosage / Q000627:therapeutic use*; D010879:Piperazines / Q000008:administration & dosage / Q000627:therapeutic use*; D011687:Purines; D012307:Risk Factors; D000068677:Sildenafil Citrate; D013450:Sulfones / Q000008:administration & dosage / Q000627:therapeutic use*; D000068581:Tadalafil; D013997:Time Factors; D014227:Triazines / Q000008:administration & dosage / Q000627:therapeutic use*; D000069058:Vardenafil Dihydrochloride; D014665:Vasodilator Agents / Q000008:administration & dosage / Q000627:therapeutic use*
chemical_list: D002243:Carbolines; D007093:Imidazoles; D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D013450:Sulfones; D014227:Triazines; D014665:Vasodilator Agents; D000069058:Vardenafil Dihydrochloride; D000068581:Tadalafil; D000068677:Sildenafil Citrate