title: Double-blind, randomized, parallel, placebo-controlled study of ibuprofen effects on thromboxane B2 concentrations in aspirin-treated healthy adult volunteers.
abstract: BACKGROUND
  Patients taking aspirin for cardioprotection may occasionally take over-the-counter (OTC) ibuprofen for pain relief, which might interfere with the antiplatelet effects of aspirin.
  
  
  OBJECTIVE
  The present study was undertaken to determine whether ibuprofen, taken according to OTC label directions, would affect inhibition of thromboxane B2 (TXB2), a surrogate for platelet inhibition.
  
  
  METHODS
  This was a prospective, multiple-dose,single-center, double-blind, randomized, parallel, placebo-controlled study. Eligible subjects received chewable, immediate-release aspirin 81 mg QD for 8 days, and were then randomized to receive either ibuprofen 400 mg TID or placebo TID, in addition to aspirin, for 10 days.
  
  
  RESULTS
  Fifty-one subjects were randomized; 47(24 placebo, 23 ibuprofen) completed the study. No subjects withdrew prematurely. Subjects were predominantly white (49%) or black (38%), and 53% were male. The mean (SD) age was 38.4 (9.8) years and mean (SD) body weight was 173.2 (26.7) pounds. On days 1, 3, 7, and 10 of the study period, mean TXB2 inhibitions were 99.24%, 98.88%, 97.75%, and 98.17% for ibuprofen and 98.82%, 98.93%, 98.75%, and 98.83% for placebo. Although a statistically significant reduction of TXBZ inhibition was seen in the ibuprofen group at days 7 and 10 (P = 0.003 and P = 0.023, respectively), TXBZ inhibition was >90% on all days tested in all subjects. Aspirin, ibuprofen, and placebo were all well tolerated. There were 3 adverse events (1 mild and 2 moderate) during the aspirin run-in period and 8 (2 mild and 6 moderate) during the randomized study period.
  
  
  CONCLUSIONS
  No clinically meaningful loss of cardioprotection was found, as reflected by TXB2 inhibition in healthy volunteers who received OTC doses of ibuprofen. When using this regimen of OTC ibuprofen with immediate-release, low-dose aspirin, concerns about the loss of cardioprotective antiplatelet effects of aspirin are not supported by this study.
authors.affiliation: Dallas Veterans Affairs Medical Center, Dallas, Texas, USA.
authors.forename: Byron
authors.initials: B
authors.lastname: Cryer
authors.forename: Roger G
authors.initials: RG
authors.lastname: Berlin
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Cooper
authors.forename: Ching
authors.initials: C
authors.lastname: Hsu
authors.forename: Suman
authors.initials: S
authors.lastname: Wason
mesh_terms: D000328:Adult; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology*; D001241:Aspirin / Q000494:pharmacology*; D004311:Double-Blind Method; D004336:Drug Antagonism; D005260:Female; D006801:Humans; D007052:Ibuprofen / Q000494:pharmacology*; D008163:Luminescent Measurements; D008297:Male; D008875:Middle Aged; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D013929:Thromboxane B2 / Q000037:antagonists & inhibitors* / Q000097:blood
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D010975:Platelet Aggregation Inhibitors; D013929:Thromboxane B2; D001241:Aspirin; D007052:Ibuprofen