title: The interaction of ibuprofen and diclofenac with aspirin in healthy volunteers.
abstract: OBJECTIVE
  Aspirin reduces the risk of myocardial infarction and stroke by inhibiting thromboxane production in platelets. This inhibition can be competitively antagonized by some non-steroidal anti-inflammatory drugs (NSAIDs).
  
  
  METHODS
  By measuring thromboxane B(2) production in healthy volunteers, we investigated whether ibuprofen (800 mg three times daily for 7 days) or diclofenac (50 mg three times daily for 7 days) taken concurrently with aspirin 80 mg (once daily for 7 days) influenced the inhibitory effect of aspirin. The effects were compared with aspirin 30 mg (once daily for 7 days), which is the lowest dose of aspirin with a proven thromboprophylactic effect.
  
  
  RESULTS
  The median percentage inhibition of thromboxane B(2) levels by 30 mg or 80 mg aspirin was 90.3% (range 83.1-96.0%) and 98.0% (range 96.8-99.2%) respectively. The inhibition by concurrent administration of slow release diclofenac and 80 mg aspirin was 98.1% (range 97.2-98.9%), indicating no interference between aspirin and diclofenac. The inhibition decreased significantly by concurrent administration of immediate release ibuprofen and 80 mg aspirin (86.6%; range 77.6-95.1%) to a level less than 30 mg aspirin.
  
  
  CONCLUSIONS
  As alternatives are easily available, NSAIDs such as diclofenac should be preferred to ibuprofen for combined use with aspirin.
authors.affiliation: Clinical Chemistry, Canisius Wilhemina Hospital, Nijmegen 6532 SZ, The Netherlands.
authors.forename: M P
authors.initials: MP
authors.lastname: Schuijt
authors.forename: H W H A
authors.initials: HW
authors.lastname: Huntjens-Fleuren
authors.forename: M
authors.initials: M
authors.lastname: de Metz
authors.forename: E J
authors.initials: EJ
authors.lastname: Vollaard
mesh_terms: D000328:Adult; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000097:blood* / Q000493:pharmacokinetics; D001241:Aspirin / Q000037:antagonists & inhibitors / Q000097:blood* / Q000493:pharmacokinetics; D018592:Cross-Over Studies; D003692:Delayed-Action Preparations; D004008:Diclofenac / Q000097:blood / Q000493:pharmacokinetics; D004347:Drug Interactions / Q000502:physiology; D005260:Female; D006801:Humans; D007052:Ibuprofen / Q000097:blood* / Q000493:pharmacokinetics; D008297:Male; D008875:Middle Aged; D010974:Platelet Aggregation / Q000187:drug effects / Q000502:physiology; D012307:Risk Factors; D013929:Thromboxane B2 / Q000037:antagonists & inhibitors / Q000097:blood
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D003692:Delayed-Action Preparations; D004008:Diclofenac; D013929:Thromboxane B2; D001241:Aspirin; D007052:Ibuprofen