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Assessment of impact of physico‐chemical drug properties on monitoring drug levels by micellar electrokinetic capillary chromatography with direct serum injection
Author(s) -
Schmutz André,
Thormann Wolfgang
Publication year - 1994
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.11501501197
Subject(s) - chemistry , micellar electrokinetic chromatography , chromatography , sodium dodecyl sulfate , lipophilicity , partition coefficient , naproxen , drug , sodium , analyte , capillary electrophoresis , pharmacology , stereochemistry , organic chemistry , medicine , alternative medicine , pathology
The impact of physico‐chemical properties of 25 compounds, including antiepileptic, anti‐inflammatory and beta‐blocking drugs, on their determination by micellar electrokinetic capillary chromatography (MECC) with direct serum injection (DSI) is discussed. Having a pH 9.2 buffer containing 75 m M sodium dodecyl sulfate (SDS), elution is dependent on hydrophobicity, the order of emergence being basically according to increasing octanol/water partition coefficients (log P values). Peak shape is determined by the dissociation behavior (expressed by p K a ) and plasma protein binding (PPB). Sharp peaks are produced by compounds having low PPB and, independently of PPB, by drugs with p K a values which are similar to the buffer pH. Broad or double peaks are established by drugs of low p K a values and significant (> about 40%) PPB. In order to evaluate the effective amount of a protein‐bound drug measured by MECC‐DSI, serum levels of drugs with different PPB, namely ethosuximide (no PPB), phenobarbital (PPB of about 50%) and naproxen (PPB > 99%) have been determined by both MECC‐DSI and MECC with extract injection (MECC‐EXI). In each case, with more than 40 sera, there is good agreement between the two sets of data. Thus, employing MECC‐DSI, total amounts of drugs are determined, i.e. a complete release of the drugs from the proteins is effected by the impact of dodecyl sulfate on the sampled proteins.