There are other options.
Rich
B
B
D002318:Cardiovascular Diseases / Q000150:complications*; D004347:Drug Interactions; D007172:Erectile Dysfunction / Q000188:drug therapy* / Q000209:etiology; D006801:Humans; D008297:Male; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology / Q000627:therapeutic use*; D010879:Piperazines / Q000494:pharmacology / Q000627:therapeutic use*; D011687:Purines; D000068677:Sildenafil Citrate; D013450:Sulfones
D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D013450:Sulfones; D000068677:Sildenafil Citrate