New warnings sought for Viagra.
D004348:Drug Labeling; D015658:HIV Infections / Q000517:prevention & control; D006801:Humans; D010879:Piperazines; D011687:Purines; D012495:San Francisco; D012749:Sexually Transmitted Diseases / Q000517:prevention & control*; D000068677:Sildenafil Citrate; D013450:Sulfones
D010879:Piperazines; D011687:Purines; D013450:Sulfones; D000068677:Sildenafil Citrate