Platelet dysfunction after intravenous ketorolac or propacetamol

Acta Anaesthesiol Scand. 2000 Jan;44(1):69-74. doi: 10.1034/j.1399-6576.2000.440113.x.


Background: Paracetamol is a weak cyclo-oxygenase inhibitor in vitro. A recent study in children has shown that high doses of paracetamol are effective and safe. We studied the effect of propacetamol on haemostasis in adult volunteers.

Methods: Ten volunteers were investigated in a double-blind, randomized, crossover study. They received propacetamol 60 mg kg(-1) or ketorolac 0.4 mg kg(-1) in saline i.v. (30 min) in two different sessions. Platelet function was evaluated before the test infusion (S-0), two (S-2) and 24 h (S-24) after the start of the infusion. Coagulation parameters (PT, APTT, factor V and VII activities) were measured at S-0, S-24 and 48 h (S-48).

Results: One of the volunteers had no secondary platelet aggregation in S-0 and was excluded from the final analysis. Two hours (S-2) after propacetamol and ketorolac administration the adrenaline (0.9 microg ml(-1) and 9.0 microg ml(-1)) induced maximal platelet aggregation was decreased compared with S-0. At S-2 platelet aggregation was inhibited more after ketorolac than after propacetamol. At 24 h after ketorolac, but not after propacetamol, there was still a decrease in the adrenaline-induced maximal platelet aggregation. Propacetamol did not affect adenosine diphosphate (ADP)-induced maximal platelet aggregation, whereas ketorolac decreased 3 and 6 microM ADP-induced maximal platelet aggregation at S-2 and S-24. However, 2 h after both ketorolac and propacetamol, thromboxane B2 (TxB2) concentration decreased in platelet rich plasma after 5 min aggregation induced by 8 microM ADP. Coagulation was unaffected.

Conclusion: Propacetamol 60 mg kg(-1) i.v. causes reversible platelet dysfunction demonstrated by a decrease in maximal platelet aggregation and TxB2 concentration. After 0.4 mg kg(-1) ketorolac i.v. platelet aggregation and TxB2 formation are inhibited more in comparison with propacetamol, and platelet dysfunction is still seen after 24 h.

Publication types

  • Clinical Trial
  • Comparative Study
  • Randomized Controlled Trial

MeSH terms

  • Acetaminophen / adverse effects
  • Acetaminophen / analogs & derivatives*
  • Adult
  • Anti-Inflammatory Agents, Non-Steroidal / adverse effects*
  • Blood Platelets / drug effects*
  • Cross-Over Studies
  • Cyclooxygenase Inhibitors / adverse effects*
  • Double-Blind Method
  • Humans
  • Infusions, Intravenous
  • Ketorolac / adverse effects*
  • Male


  • Anti-Inflammatory Agents, Non-Steroidal
  • Cyclooxygenase Inhibitors
  • Acetaminophen
  • propacetamol
  • Ketorolac