Validation of a high-performance liquid chromatography assay for quantification of caffeine and paraxanthine in human serum in the context of CYP1A2 phenotyping

Caffeine and paraxanthine HPLC assay for CYP1A2 phenotype assessment using saliva and plasma

“…, 2000; Koch et al. , 1999), the results from this method were reproducible at four different concentrations for both analytes in both matricies.…”

“…A previous study by Koch et al. (1999) showed that caffeine is stable for 1 week in serum at −20, +4 and +20°C, whereas paraxanthine was reported to be only stable for one day at room temperature (+20°C).…”

“…, 1998; Koch et al. , 1999). To determine if co‐elution also occurred with other columns, the ability of the Grace Apollo C 18 (250 × 4.6 mm, 5 µm) and the Phenomenex Aqua C 18 (150 × 4.6 mm, 5 µm) columns to separate the internal standards from paraxanthine was tested.…”

Simultaneous Diagnostic Assay of Catechol and Caffeine Using an in vivo Implanted Neuro Sensor

“…The optimum SW conditions were found to be as follows: 0.3 V amplitude, 40 Hz frequency, −0.6 V accumulation potential, 3 mV increment potential, 30 sec deposition time, and 5.0 pH electrolyte strength. The method was shown to be more sensitive than the previous DL [8][9][10][11][12][19][20][21][22]26 and could be attained at low working ranges for in vivo diagnosis. Tree electrode systems can be implanted into the fish and rat brain cell.…”

Evaluation of Gastrointestinal Transit Characteristics of Oral Patch Preparation Using Caffeine as a Model Drug in Human Volunteers

“…5. 15) As caŠeine was reported to be metabolized by CYP 1A2 and there are reports of the existence of extensive metabolizers, 10,16) pharmacogenetic factors in‰uence the pharmacokinetics of caŠeine. One more subject was involved in this study but the salivary caŠeine ER of this subject was so low that the data was not used for pharmacokinetic analysis.…”