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Pethidine binding in plasma: effects of methodological variables.
Author(s) -
La Rosa C,
Mather LE,
Morgan DJ
Publication year - 1984
Publication title -
british journal of clinical pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.216
H-Index - 146
eISSN - 1365-2125
pISSN - 0306-5251
DOI - 10.1111/j.1365-2125.1984.tb02365.x
Subject(s) - pethidine , chemistry , free fraction , dialysis , fraction (chemistry) , plasma concentration , chromatography , plasma protein binding , anesthesia , pharmacology , surgery , medicine , biochemistry , analgesic
Several methodological variables potentially influencing the plasma protein binding of [14C]‐pethidine in vitro were investigated using equilibrium dialysis and rigorous pH control. Ionic strength of buffer, pethidine concentration and 21 days of plasma samples frozen to −8 degrees C did not affect the outcome of the binding experiments. Unbound fraction decreased with increasing temperatures between 25 degrees C and 37 degrees C. Unbound fraction decreased with increased pH between pH 7.0 and 8.0; the mean unbound fraction at an equilibrium pH of 7.4 and at 37 degrees C was 0.58 (s.d. 0.03, n = 58). It is likely that previous reports of pethidine unbound fraction as being between 0.2 and 0.4 represent artefacts caused by inadequate pH control during dialysis.