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Effect of 3 g of intravenous paracetamol on post‐operative analgesia, platelet function and liver enzymes in patients undergoing tonsillectomy under local anaesthesia
Author(s) -
Silvanto M.,
Munsterhjelm E.,
Savolainen S.,
Tiainen P.,
Niemi T.,
Ylikorkala O.,
Scheinin H.,
Olkkola K. T.
Publication year - 2007
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/j.1399-6576.2007.01376.x
Subject(s) - medicine , anesthesia , diclofenac , analgesic , tonsillectomy , placebo , acetaminophen , adverse effect , morphine , thromboxane , platelet , pharmacology , alternative medicine , pathology
Background: Paracetamol is often given as an adjunctive analgesic to reduce opioid‐related adverse effects but its optimal dose is unknown. We studied the analgesic effect and safety of a single 3‐g intravenous (i.v.) dose of paracetamol in adults. Methods: One hundred and seven patients undergoing tonsillectomy under local anaesthesia were randomly allocated to receive i.v. 3 g of paracetamol, 75 mg of diclofenac or placebo prior to surgery. The consumption of post‐operative morphine using a patient‐controlled analgesia‐device was quantified for 6 h. Platelet aggregation and the concentrations of paracetamol, liver aminotransferases, glutathione transferase alpha 1‐1 (GSTA1‐1) and thromboxane B 2 were measured. Results: During the first hours after surgery, both paracetamol and diclofenac reduced ( P < 0.05) the consumption of morphine but had no effect thereafter. The values for the 6‐h cumulative consumption of morphine in patients given paracetamol (18.7 ± 13.8 mg), diclofenac (16.1 ± 9.9 mg) and placebo (22.0 ± 12.1 mg) did not differ. Paracetamol had no effect on platelet aggregation, which was impaired only by diclofenac in response to arachidonic acid ( P < 0.005). Both paracetamol ( P < 0.01) and diclofenac ( P < 0.005) inhibited the release of thromboxane B 2 at 1 h but they did not affect serum aminotransferase and GSTA1‐1 levels. One patient given paracetamol displayed a transient increase in GSTA1‐1 and liver aminotransferases. Conclusion: During the initial hours after tonsillectomy, the administration of 3 g of i.v. paracetamol and 75 mg of diclofenac reduced the consumption of morphine. Both drugs also reduced the release of thromboxane B 2 from activated platelets but only diclofenac had a negative effect on platelet aggregation. In sensitive individuals, large doses of paracetamol may disturb the hepatocellular integrity. We do not recommend the use of i.v. doses of paracetamol higher than 1 g.