title: [Effectiveness duration determines selection].
mesh_terms: D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000187:drug effects*; D002243:Carbolines / Q000493:pharmacokinetics / Q000627:therapeutic use*; D002755:Choice Behavior; D018592:Cross-Over Studies; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5; D004305:Dose-Response Relationship, Drug; D007172:Erectile Dysfunction / Q000188:drug therapy*; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate / Q000502:physiology; D008875:Middle Aged; D015337:Multicenter Studies as Topic; D010726:Phosphodiesterase Inhibitors / Q000493:pharmacokinetics / Q000627:therapeutic use*; D010879:Piperazines / Q000493:pharmacokinetics / Q000627:therapeutic use*; D011687:Purines; D016032:Randomized Controlled Trials as Topic; D000068677:Sildenafil Citrate; D013450:Sulfones; D000068581:Tadalafil; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D002243:Carbolines; D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D013450:Sulfones; D000068581:Tadalafil; D000068677:Sildenafil Citrate; D015106:3',5'-Cyclic-GMP Phosphodiesterases; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5; C517381:PDE5A protein, human