title: 1-(2-Ethoxyethyl)-1H-pyrazolo[4,3-d]pyrimidines as potent phosphodiesterase  5 (PDE5) inhibitors.
abstract: 1H-Pyrazolo[4,3-d]pyrimidines are a class of potent and selective second generation phosphodiesterase 5 (PDE5) inhibitors. This work explores the potency, selectivity and efficacy of 1-(2-ethoxyethyl)-1H-pyrazolo[4,5-d]pyrimidines as PDE5 inhibitors resulting in the advancement of a clinical candidate.
authors.affiliation: Pfizer Global Research and Development, Chesterfield, MO 63017, United States. michael.tollefson@yahoo.com
authors.forename: Michael B
authors.initials: MB
authors.lastname: Tollefson
authors.forename: Brad A
authors.initials: BA
authors.lastname: Acker
authors.forename: E J
authors.initials: EJ
authors.lastname: Jacobsen
authors.forename: Robert O
authors.initials: RO
authors.lastname: Hughes
authors.forename: John K
authors.initials: JK
authors.lastname: Walker
authors.forename: David N A
authors.initials: DN
authors.lastname: Fox
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Palmer
authors.forename: Sandra K
authors.initials: SK
authors.lastname: Freeman
authors.forename: Ying
authors.initials: Y
authors.lastname: Yu
authors.forename: Brian R
authors.initials: BR
authors.lastname: Bond
mesh_terms: D000818:Animals; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5 / Q000378:metabolism; D004285:Dogs; D004791:Enzyme Inhibitors / Q000138:chemical synthesis / Q000737:chemistry* / Q000493:pharmacokinetics; D006801:Humans; D008862:Microsomes, Liver / Q000378:metabolism; D058986:Phosphodiesterase 5 Inhibitors; D011743:Pyrimidines / Q000138:chemical synthesis / Q000737:chemistry* / Q000493:pharmacokinetics; D013329:Structure-Activity Relationship
chemical_list: D004791:Enzyme Inhibitors; D058986:Phosphodiesterase 5 Inhibitors; D011743:Pyrimidines; D054706:Cyclic Nucleotide Phosphodiesterases, Type 5