title: Preventing a Niagara of viagra.
mesh_terms: D007172:Erectile Dysfunction / Q000188:drug therapy*; D015276:Health Care Rationing; D006801:Humans; D007349:Insurance, Health, Reimbursement; D008297:Male; D010726:Phosphodiesterase Inhibitors / Q000627:therapeutic use; D010879:Piperazines / Q000627:therapeutic use*; D011687:Purines; D000068677:Sildenafil Citrate; D013450:Sulfones; D014665:Vasodilator Agents / Q000627:therapeutic use*
chemical_list: D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D013450:Sulfones; D014665:Vasodilator Agents; D000068677:Sildenafil Citrate