title: Viagra: a blueprint for safety and reliability.
mesh_terms: D000368:Aged; D018849:Controlled Clinical Trials as Topic; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D007172:Erectile Dysfunction / Q000188:drug therapy* / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D017060:Patient Satisfaction; D010879:Piperazines / Q000008:administration & dosage* / Q000009:adverse effects*; D011687:Purines; D015203:Reproducibility of Results; D018570:Risk Assessment; D012307:Risk Factors; D000068677:Sildenafil Citrate; D013450:Sulfones; D014481:United States
chemical_list: D010879:Piperazines; D011687:Purines; D013450:Sulfones; D000068677:Sildenafil Citrate