title: Pentoxifylline (Trental) does not inhibit dipyridamole-induced coronary hyperemia: implications for dipyridamole-thallium-201 myocardial imaging.
abstract: Dipyridamole-thallium-201 imaging is often performed in patients unable to exercise because of peripheral vascular disease. Many of these patients are taking pentoxifylline (Trental), a methylxanthine derivative which may improve intermittent claudication. Whether pentoxifylline inhibits dipyridamole-induced coronary hyperemia like other methylxanthines such as theophylline and should be stopped prior to dipyridamole-thallium-201 imaging is unknown. Therefore, we studied the hyperemic response to dipyridamole in seven open-chest anesthetized dogs after pretreatment with either pentoxifylline (0, 7.5, or 15 mg/kg i.v.) or theophylline (3 mg/kg i.v.). Baseline circumflex coronary blood flows did not differ significantly among treatment groups. Dipyridamole significantly increased coronary blood flow before and after 7.5 or 15 mm/kg i.v. pentoxifylline (p less than 0.002). Neither dose of pentoxifylline significantly decreased the dipyridamole-induced hyperemia, while peak coronary blood flow was significantly lower after theophylline (p less than 0.01). We conclude that pentoxyifylline does not inhibit dipyridamole-induced coronary hyperemia even at high doses.
authors.affiliation: Cardiology Unit, University of Vermont College of Medicine, Burlington.
authors.forename: K A
authors.initials: KA
authors.lastname: Brown
authors.forename: B K
authors.initials: BK
authors.lastname: Slinker
mesh_terms: D000818:Animals; D003326:Coronary Circulation / Q000187:drug effects*; D003327:Coronary Disease / Q000000981:diagnostic imaging*; D004176:Dipyridamole / Q000037:antagonists & inhibitors*; D004285:Dogs; D005260:Female; D006940:Hyperemia / Q000139:chemically induced*; D008297:Male; D010431:Pentoxifylline / Q000494:pharmacology*; D011877:Radionuclide Imaging; D013794:Thallium Radioisotopes; D013805:Theobromine / Q000031:analogs & derivatives*
chemical_list: D013794:Thallium Radioisotopes; D004176:Dipyridamole; D013805:Theobromine; D010431:Pentoxifylline