Association between caffeine metabolites in urine and muscle strength in young and older adults: A cross-sectional study from NHANES 2011-2012.

BACKGROUND: Elevated levels of reactive oxygen species may contribute to the gradual decline in muscle strength over time. Although caffeine and its metabolites have antioxidant properties that can mitigate oxidative stress, the association of caffeine and its metabolites with muscle strength remains unknown. AIM: To investigate whether caffeine metabolites in urine are associated with muscle strength in young and older adults. METHODS: A cross-sectional study was conducted with 1145 individuals aged over 20 years (n = 801 < 60 years and n = 344 ≥ 60 years) from the National Health and Nutrition Examination Survey (NHANES) 2011-2012. Muscle strength was assessed using a handgrip dynamometer, and combined grip strength was determined by summing the highest value from each hand. Caffeine and its metabolites in urine were quantified using ultra-high-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (1-methyluric acid, 3-methyluric acid, 7-methyluric acid, 1,3-dimethyluric acid, 1,7-dimethyluric acid, 3,7-dimethyluric acid, 1,3,7-trimethyluric acid, 1-methylxanthine, 3-methylxanthine, 7-methylxanthine, 1,3-dimethylxanthine, 1,7-dimethylxanthine, 3,7-dimethylxanthine, 1,3,7-trimethylxanthine, 5-acetylamino-6-amino-3-methyluracil). Linear regression analyses were performed to determine the association of caffeine and its metabolites with muscle strength in young and older adults, adjusting for confounders. RESULTS: Positive associations between muscle strength and levels of 7-methyluric acid (ß = 0.029; p = 0.021), 1,3-dimethyluric acid (ß = 0.008; p = 0.004), 3,7-dimethyluric acid (ß = 0.645; p = 0.012), 3-methylxanthine (ß = 0.020; p = 0.002), 7-methylxanthine (ß = 0.020; p = 0.006), 1,3-dimethylxanthine (theophylline) (ß = 0.030; p = 0.004) and 3,7-dimethylxanthine (theobromine) (ß = 0.035; p = 0.029) were observed in older adults. In contrast, no such associations were noted in young adults. CONCLUSION: Our study indicates a positive association between certain caffeine metabolites in urine and muscle strength in older adults, but not in younger individuals. These findings indicate that specific caffeine metabolites may contribute to an antioxidant role especially in older adults.

Determination of cocaine adulterants in human urine by dispersive liquid-liquid microextraction and high-performance liquid chromatography.

This study aimed to determine simultaneously five major street cocaine adulterants (caffeine, lidocaine, phenacetin, diltiazem, and hydroxyzine) in human urine by dispersive liquid-liquid microextraction (DLLME) and high-performance liquid chromatography. The chromatographic separation was obtained in gradient elution mode using methanol:water plus trifluoroacetic acid 0.15% (v/v) (pH = 1.9) at 1 mL min-1 as mobile phase, at 25 °C, detection at 235 nm, and analysis time of 20 min. The effect of major DLLME operating parameters on extraction efficiency was explored using the multifactorial experimental design approach. The optimum extraction condition was set as 4 mL human urine sample alkalized with 0.5 M sodium phosphate buffer (pH 12), NaCl (15%, m/v), 300 µL acetonitrile (dispersive solvent), and 800 µL chloroform (extraction solvent). Linear response (r2 ≥ 0.99) was obtained in the range of 180-1500 ng mL-1 with suitable selectivity, quantification limit (180 ng mL-1), mean recoveries (33.43-76.63%), and showing relative standard deviation and error (within and between-day assays) ≤15%. The analytes were stable after a freeze-thaw cycle and a short-term room temperature stability test. This method was successfully applied in real samples of cocaine users, suggesting that our study may contribute to the appropriate treatment of cocaine dependence or with the cases of cocaine acute intoxication.

Caffeine monitoring in biological fluids by solid surface fluorescence using membranes modified with nanotubes.

BACKGROUND: In this work, a new methodology based upon enhancement of rhodamine B fluorescent signal is proposed for the quantification of caffeine traces. METHODS: Membrane filters treated with multiple wall carbon nanotubes were employed as solid support for determination step by solid surface fluorescence. RESULTS: Experimental variables that influence the preconcentration step and fluorimetric sensitivity have been optimized using uni-variation assays, presenting linearity from 1.1 to 9.7×10(3) µg/l, with a correlation coefficient of 0.99. At optimal conditions, a limit of detection of 0.3 µg/l and a limit of quantification of 1.1 µg/l were obtained. The method showed good sensitivity and adequate selectivity and was satisfactorily applied to the determination of trace amounts of caffeine in urine, plasma and serum belonging to subjects with different sex, ages and habit of caffeine intake. CONCLUSIONS: Chemofiltration step eliminated the highly fluorescent matrix, thus enabling and allowing CF quantification, in the presence of other methylxanthines. The proposed methodology represents an innovative application of the solid surface fluorescence using membrane filters modified with MWCNTs.

Equine poisoning by coffee husk (Coffea arabica L.).

BACKGROUND: In Brazil, coffee (Coffea arabica) husks are reused in several ways due to their abundance, including as stall bedding. However, field veterinarians have reported that horses become intoxicated after ingesting the coffee husks that are used as bedding. The objective of this study was to evaluate whether coffee husk consumption causes intoxication in horses. RESULTS: Six horses fed coast cross hay ad libitum were given access to coffee husks and excitability, restlessness, involuntary muscle tremors, chewing movements and constant tremors of the lips and tongue, excessive sweating and increased respiration and heart rates were the most evident clinical signs. Caffeine levels were measured in the plasma and urine of these horses on two occasions: immediately before the coffee husks were made available to the animals (T0) and at the time of the clinical presentation of intoxication, 56 h after the animals started to consume the husks (T56). The concentrations of caffeine in the plasma (p < 0.001) and urine (p < 0.001) of these animals were significantly greater at T56 than at T0. CONCLUSIONS: It was concluded that consumption of coffee husks was toxic to horses due to the high levels of caffeine present in their composition. Therefore, coffee husks pose a risk when used as bedding or as feed for horses.

A high-performance thin-layer chromatographic technique to screen cocaine in urine samples.

Qualitative identification of cocaine and its metabolites in urine samples is generally carried out by an immunoassay technique followed by a gas chromatographic/mass spectrometric confirmation of presumptive positives. Nevertheless, other chromatographic techniques such as thin-layer chromatography or gas chromatography could also be used to screen several types of drugs of abuse especially for forensic and legal purposes. In the present work, the capability of high performance thin-layer chromatography (HPTLC) to detect cocaine in urine samples and discriminate it from interfering substances (local anaesthetic, caffeine and nicotine) was studied. Twenty urine samples of drug addicts were submitted to the HPTLC method. Unaltered cocaine present in the urine samples and cocaine obtained after methylation of benzoylecgonine (main cocaine metabolite) with diazomethane were detected in all tested samples. In conclusion, the proposed HPTLC method showed to be useful to detect cocaine in biological matrices.

Quantification of caffeine in horse urine and saliva by gas chromatography and ELISA

Foram pesquisados resíduos organoclorados em sangue humano, colhido de 122 indivíduos. Foram compostos dois grupos: um urbano e outro residente em áreas de intensa atividade agrícola. Os resíduos organoclorados pesquisados foram: ∞ - HCH; γ - HCH; Aldrin; Diedrin; Edrin; Hepatocloro; Hepatocloro epóxido; HCB; MIrex: o,p DDD; Oxiclordane; p.p Metoxicloro; p,p DDE; p,p DDD e Tranonacloro (limite de detecção = 0,010μg/L). Todos os indivíduos responderam a questionário com quesitos sobre idade, sexo, peso, atividade, local de residência, contato ou não praguidas. Todas as amostras urbanas foram negativas para organoclorados analisados. 10,5 por cento das amostras obtidas nas áreas de atividade agrícola foram positivas. Os resultados das análises do presente trabalho foram comparados com resultados pre-existentes no Rio grande do Sul. Entre a pesquisa atual e a pesquisas anteriores usada para comparação, verificou-se diminuição da incidência de organoclorados...

CYP1A2 phenotype and genotype in a population from the Carboniferous Region of Coahuila, Mexico.

CYP1A2 regulation by polycyclic aromatic hydrocarbons (PAHs) exposure and polymorphism was investigated in 46 male volunteers from the Carboniferous Region in northern Coahuila, Mexico. PAH exposure was estimated by the urinary excretion of 1-hydroxypyrene (1-OHP), whereas the regulatory effects were assessed by the caffeine metabolic ratio (CMR). Genotype was evaluated by determining 5'-flanking region (-2964) and intron I (734) polymorphisms. A statistically significant difference in the urinary 1-OHP geometric means of Barroterán, Cloete and Juárez (2.30, 0.45 and 0.04, respectively) was observed. As for the genotype, the intron I distribution was 0% C/C, 46% C/A and 54% A/A, whereas that of the 5'-flanking region was 26% G/G, 42% G/A and 32% A/A. Both distributions were in agreement with the Hardy-Weinberg equilibrium model. A greater enzyme activity was observed in the A/A compared to C/A individuals according to the CMR (P<0.001), whereas the 5'-flanking region polymorphism showed no effect on CYP1A2 enzymatic activity. These results suggest that intron I polymorphism and PAH exposure are relevant factors that modulate CYP1A2 enzymatic activity.

Study of caffeine in urine and saliva of horses subjected to urinary acidification.

The study of caffeine in racing horses has been of growing concern in veterinary sports medicine since the Association of Racing Commissioners International (ARCI) stated that it has no valid therapeutic use in racehorses. We examined the kinetic alterations in the urinary excretion and salivary secretion of caffeine in seven horses subjected to urinary acidification using ascorbic acid because this procedure can simulate the acidosis that follows anaerobic exercise. They participated in two treatment groups: the control group (SG) received 500 ml of saline and then 2.0 mg kg(-1) caffeine i.v. 30 min later; and the acidi fi ed group (AG) was subjected to urinary acidification with ascorbic acid at a dose of 0.5 g kg(-1) i.v. and then 2.0 mg kg(-1) caffeine i.v. 30 min later. Samples were collected 30 min before caffeine administration, immediately before caffeine administration (time zero) and at 0.25, 0.5, 1, 2, 4, 6, 8, 12, 24, 48 and 72 h afterwards. The samples were assayed by gas chromatography. The mean urinary pH for SG was 8.2, but for AG it was as low as 5.9 at 4 h, extending acidosis for up to 8 h. The kinetic curves for the two groups were similar for urinary excretion and salivary secretion. Differences occurred only in peak excretion and peak secretion in SG obtained at 1 h and 30 min, respectively, and in AG at 2 h and 1 h, respectively. This could be explained, in part, to the diuresis in AG compared with SG, resulting in less concentrated urine in the former group. The large difference between the pKa of caffeine and the pH of the medium may be responsible for the similar pharmacokinetics observed for the two groups.

Interação de antagonistas H IND. 2 no metabolismo enatiosseletivo do albendazol em pacientes com neurocisticercose. Cafeína como fármaco marcador do CYP1A2 / Interaction of H IND. 2 antagonists in the enantioselective metabolism of albendazole in patients with neurocysticercosis. Caffeine as pharmacological preparations maker of CYP1A2

O estudo investiga a associação da ranitidina ou da cimetidina no metabolismo enantiosseletivo do albendazol, administrado em regime de dose múltipla (7,5 mg/Kg/12 h) a pacientes (n=27) portadores da forma ativa da neurocisticercose intraparenquimatosa. Os pacientes foram divididos em 3 grupos, de acordo com a medicação associada (controle, cimetidina 800 mg/dia ou ranitidina 300 mg/dia). No 8° dia de tratamento com o albendazol, os pacientes receberam 100 mg de cafeína como fármaco marcador do CYP1A2, sendo colhidas amostras seriadas de sangue (0-24 h), uma amostra de líquido cefalorraquidiano (LCR, 0-12 h) e amostras de urina (0-8, 8-16, 16-24 h). Os metabólitos do albendazol no plasma e no LCR foram analisados por HPLC, em coluna de fase quiral e detecção por fluorescência...

Simultaneous determination of caffeine, theobromine, and theophylline by high-performance liquid chromatography.

This work relates the development of an analytical methodology to simultaneously determine three methylxanthines (caffeine, theobromine, and theophylline) in beverages and urine samples based on reversed-phase high-performance liquid chromatography. Separation is made with a Bondesil C18 column using methanol-water-acetic acid or ethanol-water-acetic acid (20:75:5, v/v/v) as the mobile phase at 0.7 mL/min. Identification is made by absorbance detection at 273 nm. Under optimized conditions, the detection limit of the HPLC method is 0.1 pg/mL for all three methylxanthines. This method is applied to urine and to 25 different beverage samples, which included coffee, tea, chocolate, and coconut water. The concentration ranges determined in the beverages and urine are: < 0.1 pg/mL to 350 microg/mL and 3.21 microg/mL to 71.2 microg/mL for caffeine; < 0.1 pg/mL to 32 microg mL and < 0.1 pg/mL to 13.2 microg/mL for theobromine; < 0.1 pg/mL to 47 microg/mL and < 0.1 pg/mL to 66.3 microg/mL for theophylline. The method proposed in this study is rapid and suitable for the simultaneous quantitation of methylxanthines in beverages and human urine samples and requires no extraction step or derivatization.

Effects of caffeine on locomotor activity of horses: determination of the no-effect threshold.

Caffeine is the legal stimulant consumed most extensively by the human world population and may be found eventually in the urine and/or blood of race horses. The fact that caffeine is in foods led us to determine the highest no-effect dose (HNED) of caffeine on the spontaneous locomotor activity of horses and then to quantify this substance in urine until it disappeared. We built two behavioural stalls equipped with juxtaposed photoelectric sensors that emit infrared beams that divide the stall into nine sectors in a 'tic-tac-toe' fashion. Each time a beam was interrupted by a leg of the horse, a pulse was generated; the pulses were counted at 5-min intervals and stored by a microcomputer. Environmental effects were minimized by installing exhaust fans producing white noise that obscured outside sounds. One-way observation windows prevented the animals from seeing outside. The sensors were turned on 45 min before drug administration (saline control or caffeine). The animals were observed for up to 8 h after i.v. administration of 2.0, 2.5, 3.0 or 5.0 mg caffeine kg(-1). The HNED of caffeine for stimulation of the spontaneous locomotor activity of horses was 2.0 mg kg(-1). The quantification of caffeine in urine and plasma samples was done by gradient HPLC with UV detection. The no-effect threshold should not be greater than 2.0 microg caffeine ml(-1) plasma or 5.0 microg caffeine ml(-1) urine.

Determinaçäo de cafeína em amostras de urina por injeçäo direta no HPLC / Determination of caffeine in urine samples by direct injection in to HPLC

Desenvolveu-se um método analítico para a extração e determinação das concentrações de cafeína em amostras de urina por cromatografia líquida de alta performance. O método envolve a injeção direta da amostra de urina em uma coluna cromatográfica ISRP (150mm X 4,6mm DI) empregando uma fase móvel composta por uma solução de fosfato dibásico de sódio 0,05 umol. L -1 (pH 8,0) e acetonitrila (90:10 v/v). As recuperações de cafeína presentes em amostras de urina fortificadas forma maiores que 98,40 mais ou menos 0,90 por cento com um desvio padrão relativo de 0,48 por cento. O limite de detecção para a determinação de cafeína foi de 0,1 mg.u L-1. O range de linearidade do detector foi determinado entre a s concentrações 0,1 a 18,0 ug.mL-1 para a cafeína.

Avaliaçäo dos teores de cafeína em amostras de urina de indivíduos experimentalmente expostos, para fins de controle da dopagem / Caffeine determination in urine samples of volunteers under experimental conditions with the aim of doping control studies

A cafeina é considerada uma substância ergogenica para os atletas e por isso a sua quantificaçäo em amostras de urina colhidas nas competiçöes esportivas tornou-se uma exigência do Comitê Olímpico Internacional. Este trabalho descreve um método para a separaçäo e quantificaçäo da cafeína em urina, utilizando a cromatografia líquida de alta eficiência, com coluna Lichrosorb (R) RP18 (5 micrometro, 200 x 4,6 mm), fase móvel acetonitrila-água (1:9) e fluxo de 1,0mL/min. A cafeína foi satisfatoriamente separada da teofilina, teobromina e paraxantina. Amostras de urina de voluntários administrados com 100mg do fármaco foram colhidas durante 24 horas, após dieta isenta de alimentos xantínicos. A cafeína foi extraida com diclorometano em meio alcalino, sendo a recuperaçäo da técnica 97,2 por cento. A precisäo para concentraçöes de 0,1 a 10,0 micrograma/mL, mostrou coeficiente de variaçäo de 3,5 por cento. A concentraçäo máxima de cafeína encontrada foi de 3,76 micrograma/mL, ficando entre 1,68 e 3,76 micrograma/mL nas primeiras urinas colhidas após a administraçäo e entre 1,27 a 3,48 micrograma/mL nas referentes à segunda colheita. O estudo da variabilidade dos teores de cafeína na urina de indivíduos expostos, mostrou ao tempo de 3 horas da curva de eliminaçäo, coeficiente de variaçäo de 24,79 por cento entre as concentraçöes de cafeína.

Teor de cafeína em amostras de urina de atletas / Caffeine levels in urine of athletes

Frente à perspectiva de quantificar cafeína em urina de atletas submetidos ao controle antidopagem, foi padronizado um método rápido sensível e específico utilizando um volume muito pequeno da amostra. Preliminarmente foi feita uma avaliaçäo dos teores normais de cafeína em urina de consumidores frequentes de café e de outros alimentos xantínicos. Em seguida, foi realizada a determinaçäo desses valores em amostras de urina de atletas submetidos ao controle antidopagem