title: Impact of the C2/C6 ratio of high-molecular-weight hydroxyethyl starch on pharmacokinetics and blood coagulation in pigs.
abstract: BACKGROUND
  High-molecular-weight, low-substituted hydroxyethyl starch (HES) may not affect blood coagulation more than low-molecular-weight, low-substituted HES. The authors assessed in vivo the effect of a lowered C2/C6 ratio on pharmacokinetic characteristics and the impact on blood coagulation of high-molecular-weight, low-substituted HES.
  
  
  METHODS
  A prospective, randomized, parallel study in 30 pigs compared HES 650/0.42/2.8 with HES 650/0.42/5.6. Before, during, and after infusion of 30 ml/kg body weight HES, blood samples were collected over 630 min to measure HES concentrations and plasmatic coagulation and to assess blood coagulation in whole blood by Thrombelastography (TEG; Haemoscope Corporation, Niles, IL). Pharmacokinetic parameters were estimated using a two-compartment model.
  
  
  RESULTS
  The elimination constant was 0.009 +/- 0.001 min(-1) for HES 650/0.42/2.8 and 0.007 +/- 0.001 min(-1) for HES 650/0.42/5.6 (P < 0.001); the area under the plasma concentration-time curve was 1,374 +/- 340 min x g/l for HES 650/0.42/2.8 and 1,697 +/- 411 min x g/l for HES 650/0.42/5.6 (P = 0.026). The measured plasma HES concentrations were not different between HES 650/0.42/2.8 and HES 650/0.42/5.6. Both HES solutions equally affected blood coagulation: Thrombelastographic coagulation index decreased similarly at the end of infusion of HES 650/0.42/2.8 and at the end of infusion of HES 650/0.42/5.6 (P = 0.293). Also, activated partial thromboplastin and prothrombin times increased similarly for HES 650/0.42/2.8 and HES 650/0.42/5.6 (P = 0.831).
  
  
  CONCLUSIONS
  Reducing the C2/C6 ratio in high-molecular, low-substituted HES solutions results in a slightly faster HES elimination. However, the blood coagulation compromising effect was unaffected.
authors.affiliation: Department of Anesthesiology, University Hospital Lausanne, Switzerland.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Schramm
authors.forename: Caroline
authors.initials: C
authors.lastname: Thyes
authors.forename: Philippe
authors.initials: P
authors.lastname: Frascarolo
authors.forename: Thierry
authors.initials: T
authors.lastname: Buclin
authors.forename: Marco
authors.initials: M
authors.lastname: Burki
authors.forename: Andreas
authors.initials: A
authors.lastname: Fisch
authors.forename: Marc-Alexander
authors.initials: MA
authors.lastname: Burmeister
authors.forename: Lars
authors.initials: L
authors.lastname: Asmis
authors.forename: Donat R
authors.initials: DR
authors.lastname: Spahn
mesh_terms: D000418:Albumins / Q000187:drug effects; D000818:Animals; D019540:Area Under Curve; D001777:Blood Coagulation / Q000187:drug effects*; D001780:Blood Coagulation Tests; D006454:Hemoglobins / Q000187:drug effects; D006895:Hydroxyethyl Starch Derivatives / Q000097:blood / Q000737:chemistry / Q000493:pharmacokinetics*; D008970:Molecular Weight; D010952:Plasma Substitutes / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics*; D011446:Prospective Studies; D011897:Random Allocation; D013329:Structure-Activity Relationship; D013552:Swine; D013916:Thrombelastography / Q000379:methods; D013997:Time Factors
chemical_list: D000418:Albumins; D006454:Hemoglobins; D006895:Hydroxyethyl Starch Derivatives; D010952:Plasma Substitutes