A Rapid and Specific High-Performance Liquid Chromatographic Assay for Theophylline in Biological Fluids

Blanchard, James; Harvey, Suzanne; Morgan, Wayne J.

doi:10.1093/chromsci/28.6.303

Cited by 15 publications

(2 citation statements)

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“…The day-to-day variation of two inhouse control plasma samples was 8.4 and 8.2% for the normal and high controls, respectively. Plasma theophylline concentrations were measured by HPLC according to the method of Blanchard (44).…”

Section: Methodsmentioning

confidence: 99%

The effect of a subnormal vitamin B-6 status on homocysteine metabolism.

Ubbink¹,

Merwe²,

Delport³

et al. 1996

J. Clin. Invest.

228

112

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Homocysteine, an atherogenic amino acid, is either remethylated to methionine or metabolized to cysteine by the transsulfuration pathway. The biochemical conversion of homocysteine to cysteine is dependent upon two consecutive, vitamin B-6-dependent reactions.To study the effect of a selective vitamin B-6 deficiency on transsulfuration, we performed oral methionine load tests on 22 vitamin B-6-deficient asthma patients treated with theophylline (a vitamin B-6 antagonist) and 24 age-and sex-matched controls with a normal vitamin B-6 status. Both groups had normal circulating vitamin B-12 and folate concentrations. Methionine loading resulted in significantly higher increases in circulating total homocyst(e)ine ( P Ͻ 0.01) and cystathionine ( P Ͻ 0.05) concentrations in vitamin B-6-deficient patients compared with controls. 6 wk of vitamin B-6 supplementation (20 mg/d) significantly ( P Ͻ 0.05) reduced post-methionine load increases in circulating total homocyst(e)ine concentrations in deficient subjects, but had no significant effect on the increase in total homocyst(e)ine concentrations in controls. The increases in post-methionine load circulating cystathionine concentrations were significantly ( P Ͻ 0.01) reduced in both groups after vitamin supplementation.It is concluded that a vitamin B-6 deficiency may contribute to impaired transsulfuration and an abnormal methionine load test, which is associated with premature vascular disease. ( J. Clin. Invest. 1996. 98:177-184.) Key words: folate • methionine • coronary heart disease • vitamin B-12 • cystathionine

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Section: Methodsmentioning

confidence: 99%

The effect of a subnormal vitamin B-6 status on homocysteine metabolism.

Ubbink¹,

Merwe²,

Delport³

et al. 1996

J. Clin. Invest.

228

112

View full text Add to dashboard Cite

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“…1 Furthermore, in order to adapt dosing, the assay of these two alkaloides in various pharmaceutical preparations and their therapeutic drug monitoring (TDM) are necessary. 4 Several techniques have been reported for the analysis and TDM of theophylline, caffeine and their combination with other drugs in pharmaceutical preparations, [5][6][7] biological fluids [7][8][9][10] and foodstuffs, 11 which are mainly based on high-performance liquid chromatography (HPLC). However, most of these reported procedures involve relatively long retention times or require lengthy sample pretreatments.…”

Section: Theophylline (Dimethylxanthine)mentioning

confidence: 99%

Simultaneous Determination of Theophylline and Caffeine by Proton Magnetic Resonance Spectroscopy Using Partial Least Squares Regression Techniques

et al. 2003

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A 1 H-NMR procedure based on an analysis of its data by a multivariate calibration method was conducted for the simultaneous determination of theophylline and caffeine in synthetic and real samples. Partial least squares regression (PLS) was chosen as the calibration method. The methyl signals of theophilline at 3.36 and 3.54 ppm that overlapped with those of caffeine were significant characteristics which were employed in this study for their analyses. The proposed method was successfully applied to recovery studies of theophylline and caffeine from real tablet samples.

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Serum/Saliva Correlations for Theophylline in Asthmatics

Blanchard¹,

Harvey²,

Morgan³

1991

The Journal of Clinical Pharma

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Theophylline levels in mixed saliva (both stimulated and unstimulated) were compared with total and free (unbound) serum theophylline levels in 28 asthmatic outpatients using theophylline regularly. Stimulated saliva predicted both total and unbound serum theophylline concentrations within +/- 1 microgram/mL in 62.5% and 92.9%, respectively, of the samples examined. In addition, the total serum levels could be used to predict unbound serum concentrations to within +/- 1 mg/L in 100% of the cases that were examined. These results indicate that saliva levels predict the unbound serum theophylline levels with greater accuracy and precision than they predict total serum theophylline levels. In addition, total serum levels can be used to reliably predict unbound serum levels. The use of mixed stimulated saliva is recommended as a reliable non-invasive method for monitoring unbound serum theophylline levels. The therapeutic range for saliva, which corresponds to the accepted total serum concentration range of 10-20 mg/L, is approximately 5.6-11.3 mg/L.

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A Rapid and Specific High-Performance Liquid Chromatographic Assay for Theophylline in Biological Fluids

Cited by 15 publications

References 0 publications

The effect of a subnormal vitamin B-6 status on homocysteine metabolism.

The effect of a subnormal vitamin B-6 status on homocysteine metabolism.

Simultaneous Determination of Theophylline and Caffeine by Proton Magnetic Resonance Spectroscopy Using Partial Least Squares Regression Techniques

Serum/Saliva Correlations for Theophylline in Asthmatics

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