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Plasma concentrations following repeated rectal or intravenous administration of paracetamol after heart surgery
Author(s) -
Holmér Pettersson P.,
Jakobsson J.,
ÖWall A.
Publication year - 2006
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.1399-6576.2006.01043.x
Subject(s) - medicine , rectal administration , suppository , anesthesia , plasma concentration , acetaminophen , pharmacokinetics , analgesic , route of administration , randomized controlled trial , loading dose , prospective cohort study , surgery , pharmacology
Background: Paracetamol is commonly used for post‐operative pain management in combination with more potent analgesics. The best route of paracetamol administration after major surgery, when oral intake may not be optimal, is not known. Our primary purpose was to study plasma concentrations after the 1st and 4th dose of 1 g of paracetamol given either rectally or intravenously (i.v.) after major surgery. Methods: In this prospective, randomized study, 48 patients undergoing heart surgery were randomized upon arrival to the intensive care unit (ICU) to receive paracetamol every 6th hour either as suppositories or intravenous injections. In half the patients ( n = 24), blood samples for paracetamol concentration were obtained before and 20, 40 and 80 min after the first dose. In the other patients ( n = 24), additional samples were taken prior to, and at 20, 40, 80 min and 4 and 6 h after, the 4th dose. Results: Plasma paracetamol concentration peaked (95 ± 36 μmol/l) within 40 min after initial i.v. administration but did not increase within 80 min after the 1st suppository. Plasma concentration before the 4th dose was 74 ± 51 and 50 ± 27 in the rectal and i.v. groups, respectively. Paracetamol concentration peaked 20 min after the 4th dose for the i.v. patients (210 ± 84 μmol/l) and declined to 99 ± 27 μmol/l at 80 min as compared with the rectal patients 69 ± 44 to 77 ± 48 μmol/l. Conclusion: Both time course and peak plasma concentrations of paracetamol given rectally differ from the one seen after intravenous administration. The clinical impact of these differences needs further investigation.