Rapid disappearance of protamine in adults undergoing cardiac operation with cardiopulmonary bypass

John Butterworth, Yonggu A. Lin, Richard C. Prielipp, Judy Bennett, John W. Hammon, Robert L. James

Research output: Contribution to journalArticlepeer-review

60 Scopus citations


Background. Despite long use of protamine in cardiac operations, neither protamine concentrations nor pharmacokinetics have been reported in patients. Methods. Twenty-eight patients (age, 26 to 80 years) undergoing various cardiac surgical procedures gave their consent to receive 250 mg of protamine sulfate administered intravenously by an infusion pump during 5 minutes. Protamine was administered at the usual intraoperative time after separation from cardiopulmonary bypass for reversal of heparin. Timed arterial blood samples were obtained after protamine infusion. Blood plasma was subjected to solid-phase extraction and highperformance liquid chromatography. Total (free + heparin-bound) protamine concentration versus time data were subjected to pharmacokinetic modeling. Results. Twenty-six patients completed the study. Total plasma protamine concentrations declined rapidly. Model-independent pharmacokinetic analysis revealed median (range) values as follows: volume of distribution, 5.4 L (0.82 to 34 L); clearance, 1.4 L/min (0.61 to 3.8 L/min); and half-life, 4.5 min (1.9 to 18 min). Schwarz-Bayesian criterion identified a two-compartment exponential model with adjustment for weight in the central compartment volume of distribution as performing better than other compartmental or Michaelis-Menten models. Conclusions. Protamine has a very short (approximately 5 minutes) half-life after a single 250-mg dose in adult patients. This short half-life could underlie recurrent anticoagulation after initial apparent reversal of heparin.

Original languageEnglish (US)
Pages (from-to)1589-1595
Number of pages7
JournalAnnals of Thoracic Surgery
Issue number5
StatePublished - Nov 1 2002
Externally publishedYes

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Copyright 2008 Elsevier B.V., All rights reserved.

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