title: Altered drug binding due to the use of indwelling heparinized cannulas (heparin lock) for sampling.
abstract: The effect of the use of the so-called heparin lock for blood sampling on the binding of propranolol has been studied and a cumulative dose-response curve to heparin constructed. The use of this method of blood sampling introduced considerable artifactual changes into the measurement of propranolol's plasma binding. The free fraction rose from 9.9% to 13.4% after only 50 U of heparin was used to flush the cannula. The increase in the free fraction of propranolol showed excellent correlation with the increase in free fatty acid levels (p less than 0.001, r = 0.996). The importance of ensuring that sampling techniques do not introduce artifactual changes in pharmacokinetic studies is emphasized.
mesh_terms: D000328:Adult; D001800:Blood Specimen Collection / Q000379:methods*; D002408:Catheters, Indwelling; D005230:Fatty Acids, Nonesterified / Q000097:blood; D006493:Heparin / Q000494:pharmacology*; D006801:Humans; D008297:Male; D004364:Pharmaceutical Preparations / Q000097:blood*; D011433:Propranolol / Q000097:blood
chemical_list: D005230:Fatty Acids, Nonesterified; D004364:Pharmaceutical Preparations; D006493:Heparin; D011433:Propranolol