title: A study of aspirin and clopidogrel in idiopathic pulmonary arterial hypertension.
abstract: Idiopathic pulmonary arterial hypertension (IPAH) is characterised by in situ thrombosis and increased thromboxane (Tx) A2 synthesis; however, there are no studies of antiplatelet therapy in IPAH. The aim of the current study was to determine the biochemical effects of aspirin (ASA) and clopidogrel on platelet function and eicosanoid metabolism in patients with IPAH. A randomised, double-blind, placebo-controlled crossover study of ASA 81 mg once daily and clopidogrel 75 mg once daily was performed. Plasma P-selectin levels and aggregometry were measured after exposure to adenosine diphosphate, arachidonic acid and collagen. Serum levels of TxB2 and urinary metabolites of TxA2 and prostaglandin I2 (Tx-M and PGI-M, respectively) were assessed. A total of 19 IPAH patients were enrolled, of whom nine were being treated with continuous intravenous epoprostenol. ASA and clopidogrel significantly reduced platelet aggregation to arachidonic acid and adenosine diphosphate, respectively. ASA significantly decreased serum TxB2, urinary Tx-M levels and the Tx-M/PGI-M ratio, whereas clopidogrel had no effect on eicosanoid levels. Neither drug significantly lowered plasma P-selectin levels. Epoprostenol use did not affect the results. In conclusion, aspirin and clopidogrel inhibited platelet aggregation, and aspirin reduced thromboxane metabolite production without affecting prostaglandin I2 metabolite synthesis. Further clinical trials of aspirin in patients with idiopathic pulmonary arterial hypertension should be performed.
authors.affiliation: Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, and Department of Medicine, Brigham and Women's Hospital, Boston, MA, USA.
authors.forename: I M
authors.initials: IM
authors.lastname: Robbins
authors.forename: S M
authors.initials: SM
authors.lastname: Kawut
authors.forename: D
authors.initials: D
authors.lastname: Yung
authors.forename: M P
authors.initials: MP
authors.lastname: Reilly
authors.forename: W
authors.initials: W
authors.lastname: Lloyd
authors.forename: G
authors.initials: G
authors.lastname: Cunningham
authors.forename: J
authors.initials: J
authors.lastname: Loscalzo
authors.forename: S E
authors.initials: SE
authors.lastname: Kimmel
authors.forename: B W
authors.initials: BW
authors.lastname: Christman
authors.forename: R J
authors.initials: RJ
authors.lastname: Barst
mesh_terms: D000328:Adult; D001241:Aspirin / Q000494:pharmacology* / Q000627:therapeutic use*; D000077144:Clopidogrel; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D006976:Hypertension, Pulmonary / Q000188:drug therapy* / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D010974:Platelet Aggregation / Q000187:drug effects*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology* / Q000627:therapeutic use*; D013928:Thromboxane A2 / Q000096:biosynthesis*; D013988:Ticlopidine / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use
chemical_list: D010975:Platelet Aggregation Inhibitors; D013928:Thromboxane A2; D000077144:Clopidogrel; D013988:Ticlopidine; D001241:Aspirin