title: The pharmacokinetics of a single dose of gentamicin (4 mg/kg) as prophylaxis in cardiac surgery requiring cardiopulmonary bypass.
abstract: BACKGROUND
  Cardiopulmonary bypass has complex effects on drug pharmacokinetics, which is important when considering the use of once-daily aminoglycoside regimens during cardiac surgery.
  
  
  OBJECTIVE
  To study the effects of cardiopulmonary bypass on the pharmacokinetics of a single dose of gentamicin (4 mg/kg).
  
  
  METHODS
  Nine patients undergoing valve replacement surgery were given a single dose of gentamicin (4 mg/kg) at induction of anaesthesia and blood was taken for assay at 0, O.5, 1, 1.5, 2, 2.5, 3, 4, 6, 10, 16, 22 and 24 h following administration. The mean (range) gentamicin Cmax was 18.7 (12.4-26.3) mg/litre. Three patients had concentrations of gentamicin after 24 h of > 1 mg/litre. During cardiopulmonary bypass, the mean (range) gentamicin half-life (t1/2) was 5.1 (2.0-15.1) h and post-bypass the t1/2 was 7.1 (3.0-13.9) h.
  
  
  CONCLUSIONS
  There is significant correlation between the elimination t1/2 and length of cardiopulmonary bypass (r = 0.89, P < 0.01). These results suggest that gentamicin excretion is delayed following cardiopulmonary bypass so that with dose regimens of > 4 mg/kg there is a risk of toxicity.
authors.affiliation: Department of Surgery, Bristol Royal Infirmary, UK.
authors.forename: D R
authors.initials: DR
authors.lastname: Lewis
authors.forename: R J
authors.initials: RJ
authors.lastname: Longman
authors.forename: J D
authors.initials: JD
authors.lastname: Wisheart
authors.forename: R C
authors.initials: RC
authors.lastname: Spencer
authors.forename: N M
authors.initials: NM
authors.lastname: Brown
mesh_terms: D000368:Aged; D019072:Antibiotic Prophylaxis / Q000379:methods*; D019540:Area Under Curve; D002315:Cardiopulmonary Bypass / Q000379:methods*; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D005500:Follow-Up Studies; D005839:Gentamicins / Q000008:administration & dosage* / Q000493:pharmacokinetics*; D006207:Half-Life; D006801:Humans; D008297:Male; D008875:Middle Aged; D016896:Treatment Outcome
chemical_list: D005839:Gentamicins