title: A note about Viagra.
mesh_terms: D019380:Anti-HIV Agents / Q000009:adverse effects*; D007172:Erectile Dysfunction / Q000139:chemically induced / Q000188:drug therapy*; D015658:HIV Infections / Q000188:drug therapy / Q000503:physiopathology; D017320:HIV Protease Inhibitors / Q000009:adverse effects*; D006801:Humans; D008297:Male; D010879:Piperazines / Q000627:therapeutic use*; D011687:Purines; D018894:Reverse Transcriptase Inhibitors / Q000009:adverse effects*; D000068677:Sildenafil Citrate; D013450:Sulfones
chemical_list: D019380:Anti-HIV Agents; D017320:HIV Protease Inhibitors; D010879:Piperazines; D011687:Purines; D018894:Reverse Transcriptase Inhibitors; D013450:Sulfones; D000068677:Sildenafil Citrate