The simultaneous determination of theophylline, theobromine and caffeine in plasma by high performance liquid chromatography

Foenander, T.; Birkett, Donald; Miners, John O.; Wing, L. M. H.

doi:10.1016/s0009-9120(80)90819-x

Cited by 33 publications

(8 citation statements)

References 8 publications

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“…They were purified by solid extraction, followed by high-pressure liquid chromatography with a fluorescence detection system [38]. Methylxanthines were quantified by high-pressure liquid chromatography [39]. …”

Section: Methodsmentioning

confidence: 99%

Chocolate flavanols and skin photoprotection: a parallel, double-blind, randomized clinical trial

Mogollon¹,

Boivin

Lemieux

et al. 2014

Nutr J

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BackgroundSolar ultraviolet (UV) radiation has deleterious effects on the skin, including sunburn, photoaging and cancer. Chocolate flavanols are naturally-occurring antioxidant and anti-inflammatory molecules that could play a role in preventing cutaneous UV damage. We investigated the influence of 12-week high-flavanol chocolate (HFC) consumption on skin sensitivity to UV radiation, measured by minimal erythema dose (MED). We also evaluated skin elasticity and hydration.MethodsIn this 2-group, parallel, double-blind, randomized controlled trial, 74 women aged 20–65 years and Fitzpatrick skin phototypes I or II were recruited from the general community in Quebec City, for randomization to either HFC (n = 33) or low-flavanol chocolate (LFC) (n = 41). A blocked randomisation (4), considering date of entry, skin type and age as factors, generated a sequentially-numbered allocation list. Study participants and research assistants were blinded. Totally, 30 g of chocolate were consumed daily for 12 weeks, followed by a 3-week washout period. MED was assessed at baseline and at 6, 9, 12 and 15 weeks. Main outcome was changes in MED at week 12.Results33 participants in the HFC group and 41 in the LFC group were analyzed with 15 weeks of follow-up. Both groups showed similarly-increased MED at 12 weeks (HFC: 0.0252 ± 0.1099 J/cm2 [mean ± standard deviation (SD)]; LFC: 0.0151 ± 0.1118; mean difference (MD): 0.0100 J/cm2; 95% confidence interval (CI): -0.0417 to 0.0618). However, after 3-week washout, the HFC group presented decreased MED (-0.0248 ± 0.1145) whereas no effect was seen in the LFC group (0.0168 ± 0.1698) (MD: -0.0417; 95% CI: -0.1106 to 0.0272). Net temple elasticity increased slightly but significantly by 0.09 ± 0.12 mm in the HFC group at 12 weeks compared to 0.02 ± 0.12 mm in the LFC group (MD: 0.06; 95% CI: 0.01 to 0.12 ). No significant adverse events were reported.ConclusionOur study failed to demonstrate a statistically-significant protective effect of HFC vs. LFC consumption on skin sensitivity to UV radiation as measured by MED.Trial registrationClinicalTrials.gov identifier: NCT01444625

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Section: Methodsmentioning

confidence: 99%

Chocolate flavanols and skin photoprotection: a parallel, double-blind, randomized clinical trial

Mogollon¹,

Boivin

Lemieux

et al. 2014

Nutr J

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“…Methylxanthines (caffeine, theobromine and theophylline) were simultaneously quantified by high-pressure liquid chromatography (HPLC) [21], by a technician blinded to participant status. Inter- and intra-assay coefficients of variation were 5.2% and 3.7%, respectively.…”

Section: Endpointsmentioning

confidence: 99%

Blood pressure and endothelial function in healthy, pregnant women after acute and daily consumption of flavanol-rich chocolate: a pilot, randomized controlled trial

Mogollon¹,

Bujold

Lemieux³

et al. 2013

Nutr J

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BackgroundSeveral randomized clinical trials (RCTs) indicate that flavanol-rich chocolate has beneficial effects on flow-mediated dilation (FMD) and blood pressure (BP). However, no RCTs have evaluated these outcomes in pregnant women. The objective of this 2-group, parallel, double-blind RCT was to examine the effects of flavanol-rich chocolate on FMD and BP in pregnant women with normal BP.MethodsForty-four healthy, pregnant women were randomized to the high-flavanol (n = 23) or low-flavanol (n = 21) chocolate consumption for 12 weeks. At randomization (0, 60, 120 and 180 min after a single 40-g dose of chocolate), 6 and 12 weeks after daily 20-g chocolate intake, we evaluated plasma concentrations of flavanols and theobromine, as well as the FMD and BP.ResultsPlasma epicatechin was significantly increased (p < 0.001) 180 min after the consumption of 40-g high-flavanol chocolate compared to low-flavanol chocolate. Theobromine concentrations were significantly higher 180 min and 12 weeks after the intake of experimental chocolate or low-flavanol chocolate (p < 0.001). FMD was not different between the 2 groups at all pre-defined time periods. No other significant within-group or between-group changes were observed.ConclusionThese results confirm the feasibility of a large-scale RCT comparing daily consumption of flavanol-rich chocolate to an equivalent placebo during pregnancy and demonstrate higher plasma epicatechin and theobromine concentration in the intervention group after acute ingestionTrial registrationClinicalTrials.gov Identifier: NCT01659060

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“…High performance liquid chromatographic (h.p.l.c.) procedures were used for the determination of plasma concentrations of theophylline (Foenander et al, 1980) and of propranolol . Similarly, urine concentrations of unchanged theophylline and theophylline metabolites (1-methyluric acid, 1MU; 3-methylxanthine, 3MX; 1,3-dimethyluric acid, 1, 3DMU) were measured by h.p.l.c.…”

Section: Analytical Proceduresmentioning

confidence: 99%

Selectivity and dose‐dependency of the inhibitory effect of propranolol on theophylline metabolism in man.

Miners¹,

Wing²,

Lillywhite³

et al. 1985

Brit J Clinical Pharma

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1 The effects of separate 5 day pretreatments of propranolol 120 mg day-1 and 720 mg day-1 on theophylline clearance and metabolism at steady-state were determined in seven healthy males. 2 Propranolol 120 mg day-1 decreased theophylline plasma clearance (CL) by 30%. Clearance of theophylline to each metabolite was reduced by this treatment, clearances to the two demethylated products by 42-43% and clearance to the 8-hydroxylation product by 27%.3 Propranolol 720 mg day-' decreased theophylline CL by 52%. Again, clearance of theophylline to each metabolite was reduced by this treatment, clearances to the two demethylation products by 73-77% and clearance to the 8-hydroxylation product by 44%. 4 These data are consistent with a dose-dependent and selective inhibitory effect of propranolol on the separate forms of cytochrome P-450 involved in theophylline demethylation and 8-hydroxylation.Keywords drug metabolism drug interactions cytochrome P-450 propranolol theophylline

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The simultaneous determination of theophylline, theobromine and caffeine in plasma by high performance liquid chromatography

Cited by 33 publications

References 8 publications

Chocolate flavanols and skin photoprotection: a parallel, double-blind, randomized clinical trial

Chocolate flavanols and skin photoprotection: a parallel, double-blind, randomized clinical trial

Blood pressure and endothelial function in healthy, pregnant women after acute and daily consumption of flavanol-rich chocolate: a pilot, randomized controlled trial

Selectivity and dose‐dependency of the inhibitory effect of propranolol on theophylline metabolism in man.

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