Investigating the Relations Between Caffeine-Derived Metabolites and Plasma Lipids in 2 Population-Based Studies

OBJECTIVE

To investigate the relations between caffeine-derived metabolites (methylxanthines) and plasma lipids by use of population-based data from 2 European countries.

METHODS

Families were randomly selected from the general population of northern Belgium (FLEMENGHO), from August 12, 1985, until November 22, 1990, and 3 Swiss cities (SKIPOGH), from November 25, 2009, through April 4, 2013. We measured plasma concentrations (FLEMENGHO, SKIPOGH) and 24-hour urinary excretions (SKIPOGH) of 4 methylxanthines-caffeine, paraxanthine, theobromine, and theophylline-using ultra-high-performance liquid chromatography-tandem mass spectrometry. We used enzymatic methods to estimate total cholesterol, high-density lipoprotein cholesterol, and triglyceride levels and the Friedewald equation for low-density lipoprotein cholesterol levels in plasma. We applied sex-specific mixed models to investigate associations between methylxanthines and plasma lipids, adjusting for major confounders.

RESULTS

In both FLEMENGHO (N=1987; 1055 [53%] female participants) and SKIPOGH (N=990; 523 [53%] female participants), total cholesterol, low-density lipoprotein cholesterol, and triglyceride levels increased across quartiles of plasma caffeine, paraxanthine, and theophylline (total cholesterol levels by caffeine quartiles in FLEMENGHO, male participants: 5.01±0.06 mmol/L, 5.05±0.06 mmol/L, 5.27±0.06 mmol/L, 5.62±0.06 mmol/L; female participants: 5.24±0.06 mmol/L, 5.15±0.05 mmol/L, 5.25±0.05 mmol/L, 5.42±0.05 mmol/L). Similar results were observed using urinary methylxanthines in SKIPOGH (total cholesterol levels by caffeine quartiles, male participants: 4.54±0.08 mmol/L, 4.94±0.08 mmol/L, 4.87±0.08 mmol/L, 5.27±0.09 mmol/L; female participants: 5.12±0.07 mmol/L, 5.21±0.07 mmol/L, 5.28±0.05 mmol/L, 5.28±0.07 mmol/L). Furthermore, urinary caffeine and theophylline were positively associated with high-density lipoprotein cholesterol in SKIPOGH male participants.

CONCLUSION

Plasma and urinary caffeine, paraxanthine, and theophylline were positively associated with plasma lipids, whereas the associations involving theobromine were less clear. We postulate that the positive association between caffeine intake and plasma lipids may be related to the sympathomimetic function of methylxanthines, mitigating the overall health-beneficial effect of caffeine intake.

Association Between Maternal Caffeine Consumption and Metabolism and Neonatal Anthropometry: A Secondary Analysis of the NICHD Fetal Growth Studies-Singletons

IMPORTANCE

Higher caffeine consumption during pregnancy has been associated with lower birth weight. However, associations of caffeine consumption, based on both plasma concentrations of caffeine and its metabolites, and self-reported caffeinated beverage intake, with multiple measures of neonatal anthropometry, have yet to be examined.

OBJECTIVE

To evaluate the association between maternal caffeine intake and neonatal anthropometry, testing effect modification by fast or slow caffeine metabolism genotype.

DESIGN, SETTING, AND PARTICIPANTS

A longitudinal cohort study, the National Institute of Child Health and Human Development Fetal Growth Studies-Singletons, enrolled 2055 nonsmoking women at low risk for fetal growth abnormalities with complete information on caffeine consumption from 12 US clinical sites between 2009 and 2013. Secondary analysis was completed in 2020.

EXPOSURES

Caffeine was evaluated by both plasma concentrations of caffeine and paraxanthine and self-reported caffeinated beverage consumption measured/reported at 10-13 weeks gestation. Caffeine metabolism defined as fast or slow using genotype information from the single nucleotide variant rs762551 (CYP1A2*1F).

MAIN OUTCOMES AND MEASURES

Neonatal anthropometric measures, including birth weight, length, and head, abdominal, arm, and thigh circumferences, skin fold and fat mass measures. The β coefficients represent the change in neonatal anthropometric measure per SD change in exposure.

RESULTS

A total of 2055 participants had a mean (SD) age of 28.3 (5.5) years, mean (SD) body mass index of 23.6 (3.0), and 580 (28.2%) were Hispanic, 562 (27.4%) were White, 518 (25.2%) were Black, and 395 (19.2%) were Asian/Pacific Islander. Delivery occurred at a mean (SD) of 39.2 (1.7) gestational weeks. Compared with the first quartile of plasma caffeine level (≤28 ng/mL), neonates of women in the fourth quartile (>659 ng/mL) had lower birth weight (β = -84.3 g; 95% CI, -145.9 to -22.6 g; P = .04 for trend), length (β = -0.44 cm; 95% CI, -0.78 to -0.12 cm; P = .04 for trend), and head (β = -0.28 cm; 95% CI, -0.47 to -0.09 cm; P < .001 for trend), arm (β = -0.25 cm; 95% CI, -0.41 to -0.09 cm: P = .02 for trend), and thigh (β = -0.29 cm; 95% CI, -0.58 to -0.04 cm; P = .07 for trend) circumference. Similar reductions were observed for paraxanthine quartiles, and for continuous measures of caffeine and paraxanthine concentrations. Compared with women who reported drinking no caffeinated beverages, women who consumed approximately 50 mg per day (~ 1/2 cup of coffee) had neonates with lower birth weight (β = -66 g; 95% CI, -121 to -10 g), smaller arm (β = -0.17 cm; 95% CI, -0.31 to -0.02 cm) and thigh (β = -0.32 cm; 95% CI, -0.55 to -0.09 cm) circumference, and smaller anterior flank skin fold (β = -0.24 mm; 95% CI, -0.47 to -0.01 mm). Results did not differ by fast or slow caffeine metabolism genotype.

CONCLUSIONS AND RELEVANCE

In this cohort study, small reductions in neonatal anthropometric measurements with increasing caffeine consumption were observed. Findings suggest that caffeine consumption during pregnancy, even at levels much lower than the recommended 200 mg per day of caffeine, are associated with decreased fetal growth.

Genetically Determined Levels of Serum Metabolites and Risk of Neuroticism: A Mendelian Randomization Study

BACKGROUND

Neuroticism is a strong predictor for a variety of social and behavioral outcomes, but the etiology is still unknown. Our study aims to provide a comprehensive investigation of causal effects of serum metabolome phenotypes on risk of neuroticism using Mendelian randomization (MR) approaches.

METHODS

Genetic associations with 486 metabolic traits were utilized as exposures, and data from a large genome-wide association study of neuroticism were selected as outcome. For MR analysis, we used the standard inverse-variance weighted (IVW) method for primary MR analysis and 3 additional MR methods (MR-Egger, weighted median, and MR pleiotropy residual sum and outlier) for sensitivity analyses.

RESULTS

Our study identified 31 metabolites that might have causal effects on neuroticism. Of the 31 metabolites, uric acid and paraxanthine showed robustly significant association with neuroticism in all MR methods. Using single nucleotide polymorphisms as instrumental variables, a 1-SD increase in uric acid was associated with approximately 30% lower risk of neuroticism (OR: 0.77; 95% CI: 0.62-0.95; PIVW = 0.0145), whereas a 1-SD increase in paraxanthine was associated with a 7% higher risk of neuroticism (OR: 1.07; 95% CI: 1.01-1.12; PIVW = .0145).

DISCUSSION

Our study suggested an increased level of uric acid was associated with lower risk of neuroticism, whereas paraxanthine showed the contrary effect. Our study provided novel insight by combining metabolomics with genomics to help understand the pathogenesis of neuroticism.

A Metabolomic Study of Biomarkers of Habitual Coffee Intake in Four European Countries

SCOPE

The goal of this work is to identify circulating biomarkers of habitual coffee intake using a metabolomic approach, and to investigate their associations with coffee intake in four European countries.

METHODS AND RESULTS

Untargeted mass spectrometry-based metabolic profiling is performed on serum samples from 451 participants of the European Prospective Investigation on Cancer and Nutrition (EPIC) originating from France, Germany, Greece, and Italy. Eleven coffee metabolites are found to be associated with self-reported habitual coffee intake, including eight more strongly correlated (r = 0.25-0.51, p < 10E-07 ). Trigonelline shows the highest correlation, followed by caffeine, two caffeine metabolites (paraxanthine and 5-Acetylamino-6-amino-3-methyluracil), quinic acid, and three compounds derived from coffee roasting (cyclo(prolyl-valyl), cyclo(isoleucyl-prolyl), cyclo(leucyl-prolyl), and pyrocatechol sulfate). Differences in the magnitude of correlations are observed between countries, with trigonelline most highly correlated with coffee intake in France and Germany, quinic acid in Greece, and cyclo(isoleucyl-prolyl) in Italy.

CONCLUSION

Several biomarkers of habitual coffee intake are identified. No unique biomarker is found to be optimal for all tested populations. Instead, optimal biomarkers are shown to depend on the population and on the type of coffee consumed. These biomarkers should help to further explore the role of coffee in disease risk.

Development of a microdevice for facile analysis of theophylline in whole blood by a cloned enzyme donor immunoassay

We have developed a microdevice for therapeutic drug monitoring. In this device, dispensing of sample and reagent was accomplished by simple manual operation of a syringe. Moreover, for a simple and rapid measurement, we used cloned enzyme donor immunoassay as a detection principle. These features and the reagent that is enclosed in microdevice beforehand make it possible to complete the facile analysis. In this paper, our model analyte was 1,3-dimethylxanthine (theophylline), a kind of bronchodilator. The fluorescence measurement of theophylline in whole blood was achieved with the limit of detection of 0.73 μg mL-1. This microdevice provides rapid analysis (4 min), requires only a small volume of sample (2 μL) and features simple operation; hence, it is readily applicable to point of care testing.

Effect of Theophylline as Adjunct to Inhaled Corticosteroids on Exacerbations in Patients With COPD: A Randomized Clinical Trial

IMPORTANCE

Chronic obstructive pulmonary disease (COPD) is a major global health issue and theophylline is used extensively. Preclinical investigations have demonstrated that low plasma concentrations (1-5 mg/L) of theophylline enhance antiinflammatory effects of corticosteroids in COPD.

OBJECTIVE

To investigate the effectiveness of adding low-dose theophylline to inhaled corticosteroids in COPD.

DESIGN, SETTING, AND PARTICIPANTS

The TWICS (theophylline with inhaled corticosteroids) trial was a pragmatic, double-blind, placebo-controlled, randomized clinical trial that enrolled patients with COPD between February 6, 2014, and August 31, 2016. Final follow-up ended on August 31, 2017. Participants had a ratio of forced expiratory volume in the first second to forced vital capacity (FEV1/FVC) of less than 0.7 with at least 2 exacerbations (treated with antibiotics, oral corticosteroids, or both) in the previous year and were using an inhaled corticosteroid. This study included 1578 participants in 121 UK primary and secondary care sites.

INTERVENTIONS

Participants were randomized to receive low-dose theophylline (200 mg once or twice per day) to provide plasma concentrations of 1 to 5 mg/L (determined by ideal body weight and smoking status) (n = 791) or placebo (n = 787).

MAIN OUTCOMES AND MEASURES

The number of participant-reported moderate or severe exacerbations treated with antibiotics, oral corticosteroids, or both over the 1-year treatment period.

RESULTS

Of the 1567 participants analyzed, mean (SD) age was 68.4 (8.4) years and 54% (843) were men. Data for evaluation of the primary outcome were available for 1536 participants (98%) (772 in the theophylline group; 764 in the placebo group). In total, there were 3430 exacerbations: 1727 in the theophylline group (mean, 2.24 [95% CI, 2.10-2.38] exacerbations per year) vs 1703 in the placebo group (mean, 2.23 [95% CI, 2.09-2.37] exacerbations per year); unadjusted mean difference, 0.01 (95% CI, -0.19 to 0.21) and adjusted incidence rate ratio, 0.99 (95% CI, 0.91-1.08). Serious adverse events in the theophylline and placebo groups included cardiac, 2.4% vs 3.4%; gastrointestinal, 2.7% vs 1.3%; and adverse reactions such as nausea (10.9% vs 7.9%) and headaches (9.0% vs 7.9%).

CONCLUSIONS AND RELEVANCE

Among adults with COPD at high risk of exacerbation treated with inhaled corticosteroids, the addition of low-dose theophylline, compared with placebo, did not reduce the number COPD exacerbations over a 1-year period. The findings do not support the use of low-dose theophylline as adjunctive therapy to inhaled corticosteroids for the prevention of COPD exacerbations.

TRIAL REGISTRATION

isrctn.org Identifier: ISRCTN27066620.

Biomarker repurposing: Therapeutic drug monitoring of serum theophylline offers a potential diagnostic biomarker of Parkinson's disease

Caffeine has been considered a neuroprotective agent against Parkinson’s disease (PD). Recent metabolomic analysis showed that levels of caffeine and its metabolites were decreased in sera from patients with PD compared with those from healthy controls. We focused on theophylline, which is one of the primary caffeine metabolites, as a candidate biomarker of PD because: (1) its serum level can be measured in hospital laboratories by standardized immunoassay kits for therapeutic drug monitoring and (2) because it is less markedly affected by caffeine intake. This was a pilot study to measure the levels of theophylline in sera of 31 patients with PD and 33 age-matched disease controls using an immunoassay kit. We confirmed the previous finding of significantly lower levels of serum theophylline in the PD group compared with control group (PD: 0.07±0.09 μg/mL, control: 0.18±0.24 μg/mL, p<0.05). Using such an approach of applying known medical biomarkers for neurodegenerative diseases may allow us to skip the process from the discovery phase to clinical application, and subsequently shorten the period of time necessary for biomarker development.

Genome-wide association study of caffeine metabolites provides new insights to caffeine metabolism and dietary caffeine-consumption behavior

Caffeine is the most widely consumed psychoactive substance in the world and presents with wide interindividual variation in metabolism. This variation may modify potential adverse or beneficial effects of caffeine on health. We conducted a genome-wide association study (GWAS) of plasma caffeine, paraxanthine, theophylline, theobromine and paraxanthine/caffeine ratio among up to 9,876 individuals of European ancestry from six population-based studies. A single SNP at 6p23 (near CD83) and several SNPs at 7p21 (near AHR), 15q24 (near CYP1A2) and 19q13.2 (near CYP2A6) met GW-significance (P < 5 × 10-8) and were associated with one or more metabolites. Variants at 7p21 and 15q24 associated with higher plasma caffeine and lower plasma paraxanthine/caffeine (slow caffeine metabolism) were previously associated with lower coffee and caffeine consumption behavior in GWAS. Variants at 19q13.2 associated with higher plasma paraxanthine/caffeine (slow paraxanthine metabolism) were also associated with lower coffee consumption in the UK Biobank (n = 94 343, P < 1.0 × 10-6). Variants at 2p24 (in GCKR), 4q22 (in ABCG2) and 7q11.23 (near POR) that were previously associated with coffee consumption in GWAS were nominally associated with plasma caffeine or its metabolites. Taken together, we have identified genetic factors contributing to variation in caffeine metabolism and confirm an important modulating role of systemic caffeine levels in dietary caffeine consumption behavior. Moreover, candidate genes identified encode proteins with important clinical functions that extend beyond caffeine metabolism.

The Evidence for Intravenous Theophylline Levels between 10-20mg/L in Children Suffering an Acute Exacerbation of Asthma: A Systematic Review

Background

Intravenous theophyllines are a second line treatment for children suffering an acute exacerbation of asthma. Various guidelines and formularies recommend aiming for serum theophylline levels between 10-20mg/l. This review aims to assess the evidence underpinning this recommendation.

Methods

A systematic review comparing outcomes of children who achieved serum theophylline concentrations between 10-20mg/l with those who did not. Primary outcomes were time until resolution of symptoms, mortality and need for mechanical ventilation. Secondary outcomes were date until discharge criteria are met, actual discharge, adverse effects and FEV1.

Data sources

MEDLINE, CINAHL, CENTRAL and Web of Science. Search performed in October 2015.

Eligibility criteria

Interventional or observational studies utilizing intravenous theophyllines for an acute exacerbation of asthma in children where serum theophylline levels and clinical outcomes were measured.

Findings

10 RCTs and 2 observational studies were included. Children with serum levels between 10-20mg/l did not have a reduction in duration of symptoms, length of hospital stay or need for mechanical ventilation or better spirometric results compared with levels <10mg/l. Levels above 20mg/l are not associated with higher rates of adverse effects. This study is limited due to heterogeneity in the way theophylline levels were reported and poor surveillance of adverse effects across studies.

Conclusion

Dosing strategies aiming for levels between 10-20mg/l are not associated with better outcomes. Clinicians should rely on clinical outcomes and not serum levels when using intravenous theophyllines in children suffering an acute exacerbation of asthma.

Maternal Caffeine Intake During Pregnancy and Child Cognition and Behavior at 4 and 7 Years of Age

Although caffeine is commonly consumed during pregnancy, there are few reports on the association of in utero caffeine exposure with offspring cognition or behavior during childhood. We evaluated the association of maternal serum paraxanthine, caffeine's primary metabolite, at <20 and ≥26 weeks' gestation with the child's intelligence quotient (IQ) and problem behaviors at ages 4 and 7 years among 2,197 mother-child pairs. The mothers were controls from a case-control study of caffeine metabolites and spontaneous abortion that was nested within the Collaborative Perinatal Project (multiple US sites, 1959-1974). Associations of paraxanthine (adjusted for maternal age, race, education, smoking, prepregnancy weight, gestational age at blood draw, and child sex) with mean IQ were assessed by linear regression and associations with problem behaviors by logistic regression. Paraxanthine concentration at ≥26 weeks' gestation manifested an inverted-J-shaped association with child's IQ at age 7 years, with a peak difference (vs. undetectable) of 0.65 points at 750 µg/L (66th percentile) and a decrement thereafter. Paraxanthine at <20 weeks was linearly associated with internalizing behavior at age 4 years (for a 500-µg/L increase, odds ratio = 1.3, 95% confidence interval: 1.1, 1.5). None of the remaining 12 associations approached statistical significance. We conclude that over a range of values applicable to most pregnant women, there was no meaningful association of serum paraxanthine level with childhood IQ or problem behaviors.

Intermittent haemodialysis and sustained low-efficiency dialysis (SLED) for acute theophylline toxicity

INTRODUCTION

Theophylline overdose can result in significant cardiovascular and neurologic toxicity and is potentially fatal. Clearance of theophylline can be enhanced by the administration of multiple-dose activated charcoal (MDAC) and extracorporeal elimination techniques. We report a case of severe theophylline toxicity initially treated with MDAC and intermittent haemodialysis. Subsequent to this, sustained low-efficiency dialysis (SLED) was undertaken. This is a prolonged renal replacement therapy that uses blood and dialysate flow rates between those of intermittent haemodialysis and continuous renal replacement therapy.

CASE REPORT

A 61-year-old man presented following ingestion of 24 g of theophylline SR (300 mg/kg), 240 mg of diazepam and 2 g of gabapentin. He required intubation and developed a supraventricular tachycardia treated with esmolol, but suffered no seizures. Serum theophylline concentration peaked at 636 μmol/L (55-110) at 9.5 h post-ingestion. Intermittent haemodialysis was performed for 4 h and resulted in a theophylline extraction ratio of 0.57 with elimination half-life of 2.3 h. SLED was subsequently performed on two occasions for 7 h. Theophylline extraction ratio ranged from 0.46 (half-life 5.3 h during the first cycle) to 0.61 (half-life 10.6 h during the second cycle). After cessation of SLED, elimination half-life was 26 h. The patient made an uneventful recovery.

DISCUSSION

Intermittent haemodialysis is the current recommended extracorporeal technique for enhancing theophylline elimination in the absence of charcoal haemoperfusion. However, SLED produced similar apparent extraction ratios with longer associated elimination half-life for theophylline than for intermittent haemodialysis. SLED is undertaken by intensive care unit (ICU) staff and may be a useful extracorporeal elimination technique in cases where access to intermittent haemodialysis, requiring specialist dialysis nursing staff, is limited or may be delayed.

Effects of fenugreek, garden cress, and black seed on theophylline pharmacokinetics in beagle dogs

CONTEXT

Herb-drug interactions are a serious problem especially for drugs with a narrow therapeutic index, taking into consideration that herbal medicines are commonly used in various parts of the world.

OBJECTIVE

The present study investigates the effect of fenugreek, garden cress, and black seed on the pharmacokinetics of theophylline in beagle dogs.

MATERIALS AND METHODS

Beagle dogs received theophylline (200 mg) orally and blood samples were withdrawn at different time intervals (0.33, 0.66, 1.0, 1.5, 2, 3, 4, 6, 8, 12, 24, and 30 h). After a suitable washout period, each herb was given orally at doses of 25, 7.5, and 2.5 g, twice daily for 7 d. On the eighth day, theophylline was re-administrated orally and blood samples were collected. Plasma concentrations of theophylline were determined using HPLC and pharmacokinetic parameters were calculated using a non-compartmental analysis.

RESULTS

Treatment with fenugreek (25 g, orally) lead to a decrease in Cmax and AUC0-t of theophylline of about 28% (p < 0.05) and 22% (p < 0.05), respectively, with no significant changes in T1/2λ compared with the baseline values. Garden cress caused a decrease in Cmax to a lesser extent and delayed Tmax of theophylline (2.10 ± 0.24 h versus 3.40 ± 0.74 h), while AUC0-∞ increased by 37.44%. No significant effect was observed for the black seed treatment on theophylline disposition as measured by Cmax, Tmax, AUC0-∞, and CL/F.

DISCUSSION AND CONCLUSION

The concurrent use of fenugreek or garden cress alters theophylline pharmacokinetic behavior in an animal model. This could represent a modulation in cytochrome P450 activity, which is responsible for theophylline metabolism in beagle dogs. Further confirmation of these results in humans will warrant changes in theophylline dosing before the co-administration of such herbs.

Metabolomics evaluation of serum markers for cachexia and their intra-day variation in patients with advanced pancreatic cancer

PURPOSE

Cancer cachexia is a multifactorial syndrome characterized by progressive loss of weight and muscle atrophy. Using metabolomics, we investigated serum markers and their intra-day variation in advanced pancreatic cancer patients with cachexia.

METHODS

Patients were enrolled in two groups: those with or without cachexia. Blood samples collected at 6:30 AM, 11:30 AM, 4:30 PM, and 9:30 PM were analyzed using metabolomics, and serum levels of IL-6, TNF-α, and leptin were measured and compared between the two groups. Intra-day variation was then evaluated.

RESULTS

Twenty-one patients were enrolled in total. In the cachexia group (n = 9), median body weight loss rate over 6 months was greater, performance status was poorer, and anorexia was more severe than in the non-cachexia group (n = 12). Each metabolites level showed substantial intra-day variation, and some of them displayed significant differences between the two groups. Levels of paraxanthine remained markedly lower in the cohort with cachexia at all measurement points. Besides, median IL-6 and TNF-α levels appeared higher and leptin concentration appeared lower in the cachexia group, albeit without statistical significance.

CONCLUSION

Some metabolites and some serological marker levels were affected by cancer cachexia. Although paraxanthine levels were consistently lower in patients with cachexia, we identified that many metabolites indicated large intra- and inter-day variation and that it might be necessary to pay attention to intra-day variation in metabolomics research.

Target-controlled formation of silver nanoclusters in abasic site-incorporated duplex DNA for label-free fluorescence detection of theophylline

A novel, label-free, fluorescence based sensor for theophylline has been developed. In the new sensor system, an abasic site-incorporated duplex DNA probe serves as both a pocket for recognition of theophylline and a template for the preparation of fluorescent silver nanoclusters. The strategy relies on theophylline-controlled formation of fluorescent silver nanoclusters from abasic site-incorporated duplex DNA. When theophylline is not present, silver ions interact with the cytosine groups opposite to the abasic site in duplex DNA. This interaction leads to efficient formation of intensely red fluorescent silver nanoclusters. In contrast, when theophylline is bound at the abasic site through pseudo base-pairing with appropriately positioned cytosines, silver ion binding to the cytosine nucleobase is prevented. Consequently, fluorescent silver nanoclusters are not formed causing a significant reduction of the fluorescence signal. By employing this new sensor, theophylline can be highly selectively detected at a concentration as low as 1.8 μM. Finally, the diagnostic capability and practical application of this sensor were demonstrated by its use in detecting theophylline in human blood serum.

Pharmacokinetic changes of unbound theophylline are due to plasma protein binding displacement and CYP1A2 activity inhibition by baicalin in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Baicalin is one of the major bioactive constituents of Scutellariae Radix, the root of Scutellariae baicalensis Georgi and possesses a wide variety of pharmacological properties.

AIM OF THE STUDY

To elucidate the effect of baicalin on the pharmacokinetics of theophylline in rats, focusing on plasma protein binding displacement and inhibition effect on CYP1A2 in vivo and in vitro.

MATERIALS AND METHODS

The study was a randomized, three-period crossover design. Nine rats were given saline (control) or 450 mg/kg baicalin (dosage regimen A or B). Dosage regimen A was administered once at 0 h. Dosage regimen B was divided into three dosages (225,112.5, 112.5 mg/kg) and was given at 0, 2 and 4 h, respectively. Then theophylline (5 mg/kg, i.v.) was administered immediately. The effect of baicalin on CYP1A2 activity was determined by metabolism of phenacetin in vitro and plasma protein binding of theophylline was determined by ultrafiltration.

RESULTS

C(max) decreased from (12.4 ± 1.6) to (8.7 ± 0.9) and (8.6 ± 2.0) mg/L, T(1/2) increased by 116 and 96%, V(d) increased by 51 and 49% for total theophylline in rats treated with dosage regimen A and B of baicalin, respectively. Cmax was significantly increased, V(d) decreased by 43 and 29% for unbound theophylline in rats treated with dosage regimen A and B of baicalin, respectively (P < 0.01). T(1/2) of unbound theophylline increased by 104% only in rats treated with dosage regimen B. No significant effects on the CL and AUC of both total and unbound theophylline were observed in the rats treated with dosage regimen A, but the CL decreased and AUC increased for total theophylline and CL decreased for unbound theophylline in the group treated with dosage regimen B (P < 0.05). Correlation analysis showed that the mean unbound theophylline (%) and mean baicalin concentration was in good correlation (P < 0.01). Baicalin decreased metabolism of phenacetin and exhibited a mixed-type inhibition in rat liver microsomes, with a K(i) value of 88.1 μM in vitro. Moreover baicalin was a competitive displacer of theophylline from plasma protein in vitro.

CONCLUSIONS

The changes in Cmax, T(1/2), CL and AUC of theophylline due to baicalin may be attributed to two mechanisms, plasma protein binding displacement and CYP1A2 activity inhibition.

Effects of unprocessed versus vinegar-processed Schisandra chinensis on the activity and mRNA expression of CYP1A2, CYP2E1 and CYP3A4 enzymes in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Schisandra chinensis (SC) is a well-known traditional Chinese herbal medicine that has been used in clinical practices for thousands of years. However, the differences between the effects of unprocessed and vinegar-processed Schisandra chinensis (VSC) on cytochrome P450 (CYP450) activities are poorly understood.

AIM OF THE STUDY

To evaluate the differences between processed and unprocessed SC on the metabolism of CYP1A2, CYP2E1 and CYP3A4 substrates in rats using a cocktail method based on a developed and validated HPLC method. We also investigate the influence of processing on the levels of CYP mRNA.

MATERIALS AND METHODS

Three probe substrates (theophylline, dapsone and chlorzoxazone) were delivered simultaneously into rats treated with single or multiple doses of processed or unprocessed SC extract. The plasma concentrations of the three probes were profiled by HPLC, and their corresponding pharmacokinetic parameters were calculated. Real-time RT-PCR was performed to determine the effects of processed and unprocessed SC on the mRNA expression of CYP1A2, CYP2E1 and CYP3A4 in the liver.

RESULTS

Treatment with single or multiple doses of either extract of SC induced CYP3A4 enzyme activity and inhibited CYP1A2 enzyme activity in rats. Furthermore, the inhibitory effect of SC was more potent after vinegar processing than without vinegar processing. CYP2E1 enzyme activity was induced after treatment with a single dose but was inhibited after multiple doses. The mRNA expression results were in accordance with the pharmacokinetic results.

CONCLUSIONS

These results provide useful scientific data for the safe clinical application of either extract of SC in combination with other drugs, which should lack the side effects induced by other herb-drug interactions.

Serum Metabolite/Caffeine Ratios as a Test for Liver Function

The aim of this study was to test the usefulness of the metabolite/caffeine ratio for the evaluation of hepatic dysfunction. Subjects with liver cirrhosis and chronic hepatitis, as well as healthy volunteers, were given the oral dose of 300 mg caffeine. Blood samples were collected after 4, 8, and 12 hours. Concentrations of caffeine (CA) and its three metabolites-paraxanthine (PX), theobromine (TB), and theophylline (TP)-were determined by high-performance liquid chromatography. Pharmacokinetic parameters of caffeine and PX/CA, TB/CA, and TP/CA ratios were calculated. Elimination of caffeine was decreased in cirrhotics in comparison with healthy volunteers, as proved by the values of clearance (0.035 vs. 0.094 L/h/kg), elimination coefficient (0.061 vs. 0.153 h(-1)), and half-life (11.4 vs. 4.3 h). Serum metabolite/caffeine ratios were significantly reduced in cirrhotic patients: PX/CA by more than 80%, TB/CA by 50% to 70%, and TP/CA by 40% to 70%. The reduction of the ratios in chronic hepatitis patients was lower and did not occur at all time points. A high correlation was found between caffeine clearance and metabolite/caffeine ratios. Metabolite/caffeine ratios calculated in a single blood sample collected 8 or 12 hours after caffeine administration could provide a practical assessment of hepatic function in cirrhotic patients. The value of the test for the chronic hepatitis patients is limited.

[Evaluation of pharmacokinetic interaction of aphobazole with CYP1A2 drug-substrate in experiments]

The effect of aphobazole on CYP1A2 (drug-marker caffeine) was studied in rats. Aphobazole was administered orally at doses 5 and 25 mg/kg, caffeine 50 mg/kg. The metabolic ratios (MR) for the caffeine metabolites (theobromine and paraxanthine) were accounted. After aphobazole administration at the effective, anxiolytic dose (5 mg/kg) for 4 days (3 times per day every 3 hours) neither the inhibiting nor the inducing effects on NOD1A2 was revealed. Increasing the aphobazole dose up to 25 mg/kg after 2 days repeated administrations of the drug made it possible to reveal a moderate inducing effect. Longer aphobazole administration (4 days), the inducing effect is amplified. Since the MR values on theobromine and paraxanthine after 2-day administration aphobazole exceed similar values in the control of 2.5 and 3.3 times, respectively. MR values after the 4-days aphobazole administration in dose 25 mg/kg exceed similar values in the control of 4.2 times for theobromine and in 6.1 times for paraxanthine.

Effect of decursin on the pharmacokinetics of theophylline and its metabolites in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Decursin is used as a traditional Asian medicine to treat various women's diseases.

AIM OF THE STUDY

Herb-drug interaction has become a serious problem since herbal medicine is extensively used in the modern world. This study investigates effects of decursin, on the pharmacokinetics of theophylline, a typical substrate of cytochrome P450 1A2 enzyme, in rats.

MATERIALS AND METHODS

After decursin pretreatment for 3 days, on the fourth day rats were administered decursin and theophylline concomitantly. The blood theophylline and its major metabolites (1-methylxanthine (1-MX), 3-methylxanthine (3-MX), 1-methyluric acid (1-MU), and 1,3-dimethyluric acid (1,3-DMU)) levels were monitored with LC-MS/MS.

RESULTS

The results indicated that the clearance, elimination rate constant (K(el)) of theophylline was significantly decreased and area under concentration-time curve (AUC), C(max), half-life was increased in decursin (25mg/kg) pretreatment when theophylline (10mg/kg) was given. In the presence of decursin, the pharmacokinetic parameters of three metabolites (1-MX, 1,3-DMU, and 1-MU) were affected and the differences were statistically significant about AUC(24)(h) parameter.

CONCLUSION

Our results suggest that patients who want to use CYP1A2-metabolized drugs such as caffeine and theophylline should be advised of the potential herb-drug interaction, to reduce therapeutic failure or increased toxicity of conventional drug therapy.

Disposition kinetics of caffeine and paraxanthine in Nile tilapia (Oreochromis niloticus): characterization of the main metabolites

The reproductive and developmental toxicities of caffeine (CA) reported in mammals have been linked with the characteristics of its kinetic disposition. Because undesirable reproductive effects in fish have also been reported, and considering that CA has been found worldwide at relatively high concentrations in most bodies of waters, this study evaluated the disposition kinetics of CA and its main metabolite paraxanthine (1,7-dimethylxanthine; PX) in Nile tilapia after a single intraperitoneal administration (4 mg/kg). CA showed rapid absorption, first-order elimination with biexponential decay, rapid intercompartmental transfer, wide distribution in almost the entire body water (apparent volume of distribution [Vd(ss)] 0.45 l/kg), terminal elimination half-life (t(1/2) (β)) 4.08 h, and systemic clearance (Cl) 0.75 ml/min/kg; there were no important differences between parameters determined in plasma or in other organs (liver and gills). PX was rapidly formed in liver, showing saturable-kinetic properties in this organ, with V(max) 8.11 μg/g h and K(m) 12.58 μg/g. The terminal elimination linear process was similar between matrices, with a half-life (t(1/2 el)) 2.12 h, Vd(ss) 0.35 l/kg, and Cl 1.24 ml/min/kg. CA in tilapia was extensively metabolized to 1-methyl-uric acid and 1-methyl-xanthine in all of the organs studied. Metabolic and kinetic patterns were comparable with those reported for mammals. The observation of a concentration-dependent kinetic of PX is an important finding. Thus, toxicities of CA in fish would appear to be similar to those in mammals and should be considered in the risk assessments for this species, especially during the early stages of development.

Clinical and physiological correlates of caffeine and caffeine metabolites in primary insomnia

OBJECTIVES

To explore the relationship between plasma concentrations of caffeine and subjective and polysomnographic measures of sleep in both good sleeper controls (GSC) and individuals with primary insomnia (PI), following the consumption of low-moderate quantities of caffeine in the home environment.

METHODS

65 PI and 29 GSC, each consuming < 4 four coffee cup equivalents of caffeine daily, were recruited. Subjects completed a diary detailing sleep habits and caffeine consumption, one night of polysomnography, and a blood sample for measurement of plasma caffeine and its metabolites at bedtime. Plasma concentrations of caffeine, its primary metabolite, paraxanthine, and other metabolites were determined for each subject and correlated with self-report and polysomnographic measures.

RESULTS

No statistically significant differences were found between GSC and PI with respect to number of caffeinated beverages consumed (p = 0.91), estimated absolute caffeine ingestion (p = 0.48), time of caffeine consumption (p = 0.22), or plasma concentrations of caffeine (p = 0.92) or paraxanthine (p = 0.88). Significant correlations were found between plasma concentrations of caffeine/paraxanthine and endorsed caffeine intake (r = 0.58, p < 0.05) and estimated absolute caffeine ingestion (r = 0.57, p < 0.05). Plasma caffeine/paraxanthine was significantly correlated with percent stage 1 sleep (r = 0.32, p < 0.05). However, plasma concentrations of caffeine/paraxanthine were not significantly correlated with other subjective or polysomnographic measures of sleep disturbance in either GSC or PI.

CONCLUSIONS

These data suggest that low-moderate amounts of caffeine consumed in the home environment, and mostly during morning hours, have little effect on subjective or polysomnographic measures of sleep in GSC or PI.

Common Drugs that May Invalidate Spectrophotofluorometric Assays of Blood Griseofulvin

Studies have been made of the potential effects of aspirin, salicylic acid, phenacetin, paracetamol, codeine, caffeine, theophylline and quinine on the spectrophotofluorometric assay of griseofulvin in blood. Aspirin, salicylic acid or quinine are likely to give falsely high values. Detection of this bias by inspecting the fluorescence spectra of the extracted griseofulvin is not always possible.

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

Caffeine has been extensively used as a probe to measure CYP1A2 activity in humans with caffeine clearance or the paraxanthine (major metabolite of caffeine) to caffeine concentration ratio being regarded as the preferred metric. A simple reverse-phased C(18) HPLC assay using ethyl acetate liquid-liquid extraction was developed to quantitate caffeine and paraxanthine concentrations in saliva and plasma. The mobile phase consisted of acetonitrile-acetic acid-H(2)O (100:1:899) and analytes were quantitated with UV detection at 280 nm. The extraction recovery for paraxanthine and caffeine was approximately 70% in both saliva and plasma. The assay was linear over the concentration ranges 0.05-2.50 and 0.05-5.00 µg/mL, for paraxanthine and caffeine, respectively, in saliva. In plasma the assay was linear over the ranges 0.025-2.50 and 0.025-5.00 µg/mL for paraxanthine and caffeine, respectively. Intra- and inter-assay precision and accuracy were less than 15%. Detection limits were 0.015 µg/mL for paraxanthine and caffeine in saliva, while it was 0.005 µg/mL for paraxanthine and caffeine in plasma. Utility was established in samples collected from two healthy volunteers who abstained from caffeine for 24 h and received a single 100 mg oral dose of caffeine. The assay developed is a robust, simple and precise technique to measure caffeine and paraxanthine in saliva and plasma of healthy volunteers after a single oral dose of caffeine.

The effect of 1-furan-2-yl-3-pyridine-2-yl-propenone on pharmacokinetic parameters of theophylline

The pharmacokinetic parameters of theophylline in rats did not change significantly when the drug was intravenously administered after three consecutive days of pretreatment with 17 mg/kg, orally, of 1-furan-2-yl-3-pyridine-2-yl-propenone (FPP-3), an investigatory drug having dual inhibitory action on cyclooxygenase (COX) and 5-lipoxygenase (5-LOX). However, significant changes were found in the pharmacokinetic parameters of the drug at doses of 34 mg/kg and more of FPP-3. Results of cytochrome P450 activity test indicated that the alteration in pharmacokinetic parameters of the drug appears to be due to the inhibitory effect of FPP-3 on cytochrome P450 1A which is responsible for the metabolism of theophylline. Methoxyresorufin-O-demethylase (MROD) and ethoxyresorufin-O-deethylase (EROD) activity assays revealed that the relative activities of cytochrome P450 1A1 and 1A2 were dose-dependently reduced in the presence of 1, 5, and 10 microM FPP-3 concentrations. Taking into consideration that FPP-3 is intended to be primarily used by geriatric patients with chronic diseases and therefore may be used in long-term basis, the investigatory drug needs to be assessed thoroughly in terms of drug interaction with other commonly prescribed medications.

Drug metabolizing enzyme CYP1A2 status in pediatric patients with hemoglobin E-beta thalassemia

OBJECTIVE

To evaluate the drug metabolizing enzyme CYP1A2 activity in pediatric hemoglobin E-beta-thalassemia patients, since CYP1A2 is responsible for the metabolism of a number of drugs. Alteration of its activity may have clinical consequences.

MATERIAL AND METHOD

Twenty-three hemoglobin E-beta thalassemia pediatric patients and 24 age-matched controls were recruited in the present study. Caffeine in the form of a soft drink was orally administered as a test probe for CYP1A2 activity. Plasma collected at pre-dose and 6 hr after intake was analyzed for the levels of caffeine and paraxanthine, its major metabolite to represent the activity of CYPIA2.

RESULTS

Biochemical markers, including blood glutathione and urinary lipid hydroperoxides indicated that patients were in an oxidant stress state. The plasma ratio of paraxanthine to caffeine was unchanged between patients and controls. Multiple regression analysis revealed that gender and the liver enzyme were the significant determinants of CYP1A2 activity (adjusted r2 = 0.48, p < 0.001). Male gender was associated with higher activity of CYP1A2 activity.

CONCLUSION

The CYP1A2 activity is not apparently changed in thalassemia patients despite the presence of an oxidative stress state.

On-line hemodialysis and hemoperfusion in a girl intoxicated by theophylline

In a suicidal attempt, a 15-year-old girl had ingested about 40 g of theophylline from sustained-release preparations. Symptoms of intoxication increased and serum concentrations of theophylline rose from 438 to 1,000 mumol/l. Conservative therapy was also combined by the use of hemodialysis as well as charcoal hemoperfusion on line. Treatment successfully reduced side-effects and S-theophylline within 12 hours and the patient could leave the hospital without residual sequelae. The combination of hemodialysis and hemoperfusion may reduce the risk of hypopotassiemia and hypocalcemia as well as increase in the clearance of the drug.

Chitosan and Sodium Sulfate as Excipients in the Preparation of Prolonged Release Theophylline Tablets

The major objectives of this study were to monitor the effect of cross-linking of cationic chitosan in acidic media with sulfate anion during granules preparation by wet granulation method prior to tableting using theophylline (TPH) as a model drug. The prepared granules and the compressed tablets were subjected to in vitro evaluation. The properties of the prepared matrix granules and the compressed tablets were dependent on chitosan:sodium sulfate weight ratios, chitosan content, and molecular weight of chitosan. The prepared granules of all batches showed excellent to passable flowability and were suitable for compression into tablets. Most of the granules were hard and expected to withstand handling during the subsequent compression into tablets. Granules with high friabilities were only those prepared with a high amount of sodium sulfate or low amount of chitosan. Compression of granule batches yield nondisintegrating tablets that showed a decrease in tensile strength with the increase of sodium sulfate content at high chitosan:sodium sulfate weight ratio or with decrease of chitosan content. On the other hand, friability of tablets was increased in the presence of an excessive amount of sodium sulfate and low chitosan content as observed with granules. Slow TPH release from the formulated tablets was achieved at 1:0.5 and 1:1 chitosan:sodium sulfate weight ratios where all or most of the cationic chitosan and sulfate anions were used in a cross-linking reaction during wet granulation. Ratios of 1:2 and 1:3 showed fast drug release, which support the hypothesis that excessive unreacted water-soluble sodium sulfate might increase the porosity of the nondesintegrating tablets during dissolution. Slow drug release was also obtained with high molecular weight chitosan, whereas changing the hardness of the tablets did not significantly change the release profile of the drug as long as the tablets are intact during dissolution. Furthermore, slow drug release was observed as the total amount of chitosan was increased in the formulated tablets. A comparative in vivo study between the chosen formulated tablets (1:1 chitosan:sodium sulfate ratio that contains 10% high molecular weight chitosan) and the commercial Quibron tablets indicated prolonged appearance of the drug in dogs' plasma for both formulations with no significant differences (p > 0.05) in rate and extent of drug absorption. The formulated tablets showed 103.16% bioavailability relative to that of the commercial tablets.

[Clinical review of patients with seizures that developed during theophylline administration--(III) Safety of theophylline examined in patients who had sequelae or died]

OBJECTIVE

To examine the causes of sequelae or death of patients who presented them subsequently to seizures that developed during theophylline administration.

METHODS

Among 334 patients who had been examined in Study (I), we extracted 56 who had sequelae or died subsequently to the onset of seizures and examined their causes.

RESULTS

Many patients had fever at the onset of seizures, many patients had neurologic predispositions prior to seizure onset, and only one patient was found to be free from fever and neurologic findings. At the onset of seizures, most of these patients had blood theophylline concentrations that were within or inferior to the target range (5-15 microg/mL).

CONCLUSIONS

We presume it necessary to pay heed to fever and neurologic predispositions in order to prevent sequelae or death that may occur subsequently to seizures that developed during theophylline administration.

Comparative bioavailability and in vitro in vivo correlation of two sustained release brands of theophylline: tablets and pellets

To investigate the influence of dosage forms on bioavailability, a randomized single-dose crossover study under fasting conditions was conducted using two commercially available sustained release products, Quibron SR tablets and Respro-SR pellets filled Capsules containing 300mg theophylline. A group of 12 healthy, male human subjects participated in this study. Serial blood samples were collected at 0, 1, 2, 3, 4, 6, 8, 10, 12 and 24 h. Theophylline was measured by high-performance liquid chromatography while absorption profiles were derived using Wagner-Nelson equation. The bioavailability of Quibron SR tablets was compared with Respro-SR pellets filled Capsules 300 mg using pharmacokinetic parameters Cmax, Tmax, AUC(0-t), and AUC(0-alpha). In addition, the 90% confidence interval (CI) for the ratio of logarithmic transformed C(max) and AUC(0-alpha) was also used to determine bioequivalence. The T/R (test/reference) ratio of Quibron SR tablets was quite close to the prescribed limits of bioequivalence i.e. 80-125%. No statistically difference was observed between the log transformed AUC(0-agr;) (P=0.971) values as well as log transformed C(max) values (P=0.854) indicating bio-availability and the extent of absorption of two brands were comparable. Moreover, the value of correlation coefficients for % in vivo absorption versus % in vitro dissolution of the two products was calculated to be 0.9533 for Respro-SR capsule and 0.9789 for Quibron-SR tablets.

Severe metabolic complications from theophylline intoxication

Theophylline is commonly used in the treatment of bronchospastic lung disease. In addition to gastrointestinal and cardiac dysfunction, hypokalaemia, lactic and ketoacidosis can complicate theophylline overdose. Clinicians frequently fail to identify theophylline's role when complications develop. A case of an 80-year-old man who developed profound metabolic disturbances while hospitalized is presented. The typical causes of these abnormalities were absent, theophylline levels were elevated, and the patient recovered after theophylline was held. Based on our case and review of the literature, we discuss the reasons why theophylline toxicity is under-recognized, and propose mechanisms for the rare metabolic abnormalities identified in this case. A high index of suspicion for theophylline toxicity should be maintained and it should be considered when unexplained acidosis or hypokalaemia occur.

Perinatal dioxin exposure, cytochrome P-450 activity, liver functions and thyroid hormones at follow-up after 7-12 years

OBJECTIVES

Prenatal and lactational exposure to Dutch "background" dioxin levels may cause health effects spanning many years. In addition, perinatal studies have shown a relationship between dioxin exposure and thyroid disturbance. To assess the later health effects of prenatal and lactational dioxin exposure on liver function we measured plasma ALAT and ASAT levels amongst our longitudinal cohort, as was done perinatally and at 2(1/2) years. The children underwent a caffeine loading test to determine CYP1A2 activity. To assess the later effects on thyroid function we measured plasma TSH and FT4.

STUDY DESIGN

A longitudinal cohort of 37 healthy children (age 7-12, mean 8.2 years), with documented prenatal and lactational dioxin exposure, ingested 3mg caffeine/kg BW 6h prior to blood withdrawal. Paraxanthine/caffeine molar ratio, ALAT, ASAT, TSH and FT4 were determined in venous blood.

RESULTS

Linear regression of ASAT and ALAT revealed no relation with prenatal and lactational dioxin exposure. No correlation was found between the paraxanthine/caffeine molar ratio and prenatal and lactational dioxin exposure. Linear regression of TSH and FT4 revealed no relation with prenatal and lactational dioxin exposure.

CONCLUSION

This follow-up has shown a normalisation of previously abnormal ALAT and ASAT levels, indicating a transient effect. CYP1A2 activity, measured by means of a caffeine-loading test, revealed no correlation with the prenatal and lactational exposures. A normalisation of previously abnormal thyroid hormone homeostasis was seen, also possibly indicating a transient effect. This study provides new data on long-term follow-up after perinatal dioxin exposure to background levels of dioxins.

In-vitro/in-vivo correlation of pulsatile drug release from press-coated tablet formulations: A pharmacoscintigraphic study in the beagle dog

The aim of the current study was to investigate the in-vitro and in-vivo performance of a press-coated tablet (PCT) intended for time delayed drug release, consisting of a rapidly disintegrating theophylline core tablet, press-coated with barrier granules containing glyceryl behenate (GB) and low-substituted hydroxypropylcellulose (L-HPC). The PCTs showed pulsatile release with a lag time dependent upon the GB and L-HPC composition of the barrier layer. In-vivo gamma-scintigraphic studies were carried out for PCTs containing GB:L-HPC at 65:35 w/w and 75:25 w/w in the barrier layer in four beagle dogs, in either the fed or fasted state. The in-vivo lag time in both the fed and fasted states did not differ significantly (p>0.05) from the in-vitro lag time. Additionally, no significant difference (p<0.05) between in-vivo fed and fasted disintegration times was observed, demonstrating that in-vivo performance of the PCT was not influenced by the presence or absence of food in the gastrointestinal tract. A distinct lag time was obtained prior to the appearance of drug in plasma and correlated (R2=0.98) with disintegration time observed from scintigraphic images. However, following disintegration, no difference in pharmacokinetic parameters (AUC(0-6 dis), K(el), Cmax) was observed. The current study highlighted the potential use of these formulations for chronopharmaceutical drug delivery.

Pharmacokinetics of an extended-release theophylline product in cats

OBJECTIVE

To evaluate the pharmacokinetics of a brand of extended-release theophylline tablets and capsules in healthy cats.

DESIGN

Randomized 3-way crossover study.

ANIMALS

6 healthy cats.

PROCEDURES

A single dose of aminophylline (10 mg/kg [4.5 mg/lb], IV), a 100-mg extended-release theophylline tablet, or a 125-mg extended-release theophylline capsule was administered to all cats. Plasma samples were collected via preplaced central catheters throughout a 36-hour period. Plasma samples were frozen until analyzed by use of a fluorescence polarization monoclonal immunoassay.

RESULTS

All cats tolerated drug administration and plasma collection with no adverse effects. Peak concentrations were reached for both orally administered products between 8 and 12 hours after administration. Bioavailability was excellent. Plasma concentrations were within the human therapeutic concentration of 5 to 20 microg/mL.

CONCLUSIONS AND CLINICAL RELEVANCE

Daily administration of the brand of theophylline tablets and capsules used in this study at 15 mg/kg (6.8 mg/lb) and 19 mg/kg (8.6 mg/lb), respectively, maintained plasma concentrations within the desired therapeutic range in healthy cats.

In vitro and in vivo sustained-release characteristics of theophylline matrix tablets and novel cluster tablets

We compared the in vitro/in vivo properties of theophylline between two sustained-release preparations, which are administered once a day. Tablet A is a swelling/disintegration-type matrix tablet consisting of hydrophobic wax granules and hydrophilic polymer granules (cluster tablets). Tablet B is a matrix tablet consisting of hydrophilic polymer granules. We conducted a dissolution test with JPXIV in vitro, and compared the results between the two preparations. Neither pH nor agitation intensity influenced these preparations. After they were immersed in oleic acid, there were no marked changes in the dissolution properties in the dissolution test. After administration of Tablets A and B containing theophylline at 200mg to fasted dogs, we compared plasma level profiles of theophylline. The mean plasma level of theophylline gradually increased to a maximum (7.17microg/mL) 4h after administration of Tablet A. After administration of Tablet B, a similar finding was noted, with a maximum of 6.09microg/mL. Tablet B showed a higher coefficient of variation (CV) for the plasma level at each point. Subsequently, we administered two tablets of preparations A and B containing theophylline at 200mg to healthy volunteers who had not been fasted, and compared plasma level concentration of theophylline. The mean plasma level of theophylline gradually increased to a maximum (6.09microg/mL) 12h after administration of Tablet A, but then decreased, with a half-life of 9.10h. After administration of Tablet B, a similar finding was noted, with a maximum of 7.87microg/mL and a half-life of 7.76h. Tablet A showed a significantly higher plasma concentration 1 and 2h after administration; however, there were no significant differences at other points. The C(max) of Tablet B was significantly higher than that of Tablet A. However, there were no significant differences in other pharmacokinetic parameters between the two preparations. The T(max) of Tablet A was 10-12h after administration, relatively constant. However, that of Tablet B was 10-18h after administration. The CV for T(max) was 9.8% for Tablet A and 22.0% for Tablet B. After administration of Tablet B, the plasma level of theophylline varied at each point. Based on these results, inter-subject variations after administration of Tablet A may be less marked than those after administration of Tablet B. It is concluded that, the cluster tablets A developed in this study showed significantly less inter-subject variation of theophylline plasma levels than the conventional matrix tablets B.

[A clinical review of patients with convulsions during theophylline administration II: points to consider in administration and prognosis as determined in patients with theophyline toxicosis]

OBJECTIVES

To discover features of patients with theophylline toxicosis among patients who developed convulsions during theophylline administration.

METHODS

Fifteen patients, whose measured or estimated blood theophylline concentration at the time of convulsion development was >/=40 microg/mL, were extracted out of 334 patients who were reported between October 1987 and April 2004 and who developed convulsions during theophylline administration (oral theophylline: 255 patients; intravenous theophylline: 79 patients). Patient background, state of drug administration, blood theophylline concentration, presence or absence of status epilepticus, and outcome were examined.

RESULTS

Young children and children with fever were predominant, and eight of 15 patients had both features. Furthermore, the dose exceeded the currently recommended target dose in most of patients whose given dose is known. Patients with misdispensing and patients having problems with administration and ingestion methods were included in them. Outcomes included one case of death, two cases of sequelae, 11 cases of recovery or alleviation, and 1 case of unknown. The patient who died took large doses of theophylline, and both of two patients who had sequelae had fever associated with an infection.

CONCLUSIONS

Our study revealed 1) heed should be given to the age of the affected child and to theophylline administration when fever is present in order to avoid theophylline toxicosis and 2) many patients with the toxicosis (11/15) present a relatively favorable prognosis.

Herb-drug interactions: Effect of Ginkgo biloba extract on the pharmacokinetics of theophylline in rats

Herbal medicines have received great attention as alternative medicines in recent years and are also referred to as a dietary supplement or health food. Ginkgo biloba extract (GBE) is one of the most popular herbal medicines. However, little is known about the metabolic interactions between GBE and clinically used drugs. This study attempted to investigate the effect of GBE on the pharmacokinetics of theophylline, a cytochrome P450 (CYP) 1A2 substrate and an important therapeutic agent with narrow therapeutic window used for the treatment of asthma. Commercial GBE (10 or 100 mg/kg, p.o.) or water (control group) was given to rats (6 rats for each group) for 5 consecutive days and on the sixth day theophylline (10 mg/kg) was administered either orally or intravenously. The results showed that pretreatment of rats with GBE resulted in an increase in the total clearance of theophylline of about 30% (GBE 10 mg/kg, P<0.05) and 70% (GBE 100 mg/kg, P<0.01) compared with the control group after intravenous administration of theophylline (10 mg/kg). After oral administration of theophylline (10 mg/kg), the AUC(0-24h) of theophylline was reduced by 40% following pretreatment with GBE (100 mg/kg, P<0.01). These results demonstrate that GBE pretreatment increased CYP1A2 metabolic activity and the clearance of theophylline in rats.

Weighted target interval stochastic control methods with global optimization and their applications in individualizing therapy

Several improvements on the target interval stochastic control (TISC) method are addressed for individualizing therapy. In particular, a global optimization control strategy is implemented to obtain the optimal dosage regimen, and weighting functions are introduced to balance the drug efficacy and the risk of toxicity. Since general guidance is often lacking in the determination of a weighting function, we introduce a systematic approach, i.e., the standard reference gamble method of medical decision theory, for the determination of the weighting function. The population model for the individualization of theophylline therapy reported by D'Argenio and Katz is applied in this research. The present method of the integration of weighting functions and global optimal strategy offer an effective and safe means to balance the drug efficacy and risk of toxicity. In addition, it also achieves better accuracy than the existing TISC method which uses a local optimal strategy.

Appropriate phenotyping procedures for drug metabolizing enzymes and transporters in humans and their simultaneous use in the "cocktail" approach

Phenotyping for drug metabolizing enzymes and transporters is used to assess quantitatively the effect of an intervention (e.g., drug therapy, diet) or a condition (e.g., genetic polymorphism, disease) on their activity. Appropriate selection of test drug and metric is essential to obtain results applicable for other substrates of the respective enzyme/transporter. The following phenotyping metrics are recommended based on the level of validation and on practicability: CYP1A2, paraxanthine/caffeine in plasma 6 h after 150 mg caffeine; CYP2C9, tolbutamide plasma concentration 24 h after 125 mg tolbutamide; CYP2C19, urinary excretion of 4'-OH-mephenytoin 0-12 h after 50 mg mephenytoin; CYP2D6, urinary molar ratio debrisoquine/4-OH-debrisoquine 0-8 h after 10 mg debrisoquine; and CYP3A4, plasma clearance of midazolam after 2 mg midazolam (all drugs given orally).

A simple and rapid HPLC/UV method for the simultaneous quantification of theophylline and etofylline in human plasma

A simple, sensitive and selective high performance liquid chromatography (HPLC) method with ultraviolet detection (272 nm) was developed and validated for the simultaneous quantification of theophylline and etofylline in human plasma. Following rapid sample preparation, the analytes and internal standard (hydrochlorothiazide) were separated using an isocratic mobile phase on a reverse phase C18 column. The lower limit of quantification was 100 ng/mL for both theophylline and etofylline with a relative standard deviation of less than 6%. A linear dynamic range of 100-10,000 ng/mL for both theophylline and etofylline was established. This HPLC method was validated with between-batch precision of 2.2-6.0 and 1.4-3.7% for theophylline and etofylline, respectively. The between-batch accuracy was 94.3-98.0 and 95.4-98.2%, respectively. Stability of theophylline and etofylline in plasma was excellent, with no evidence of degradation during sample processing (autosampler) and 30 days storage in a freezer. This validated method is simple and rugged enough to be used in pharmacokinetic studies.

First-line therapy for theophylline-associated seizures

Theophylline-associated seizures (TAS) are considered a neurologic emergency, as they can sometimes be intractable and difficult to stop with standard treatments such as intravenous administration of diazepam. As a consequence, a proportion of patients who experience status epilepticus while receiving theophylline will require endotracheal intubation. The optimal first-line therapy for TAS has not yet been fully investigated. We compared 54 cases of TAS with 779 cases of non-TAS, that had presented at a single institution between 1991 and 2002. Among the 54 cases of TAS, 36 experienced generalized tonic-clonic seizures, with the remainder experiencing partial seizures. TAS occurred mainly in children under 3 years of age, and serum theophylline levels were within the therapeutic range in 78% of the cases. The duration of TAS tended to be longer than for non-TAS, and intravenous administration of diazepam was less effective in controlling TAS (45%), compared with non-TAS (68%). Many cases required repeated injections of diazepam, and 15 cases (27%) eventually required endotracheal intubation. Reports concerning the therapy for TAS were also reviewed. Theophylline is known to antagonize the effects of benzodiazepines, and this may explain why drugs such as diazepam are relatively ineffective in treating TAS. In TAS, the prompt use of barbiturates is recommended when diazepam is not effective, to avoid potential brain injury secondary to status epilepticus.

Theophylline granule formulation prepared by the wet granulation method: comparison of in vitro dissolution profiles and estimation of in vivo plasma concentrations

The primary and secondary objectives of this study were to develop and evaluate the predictability of in vitro-in vivo correlation models for theophylline sustained release (SR) granules. Theophylline SR granules meeting the USP Drug Release Test criteria were prepared using ethyl cellulose (EC) and/or stearyl alcohol (SA) and the wet granulation method. In vitro dissolution studies of granule formulation were performed, and a commercial dosage form was prepared using USP XXIII apparatus II at pH 4.5. Differences and similarities between in vitro dissolution curves were compared using both model-dependent (t-test) and -independent (f1, f2 test) statistical techniques, and it was shown that the three dissolution profiles i.e model-dependent, model-independent, and methods based on ANOVA were very similar. The in vivo performance of the commercial dosage form was tested by oral route using male rabbits and in vitro-in vivo correlations were established. This study indicates that the dosage forms with similar in vitro dissolution profiles may have a similar in vivo performance, and that this performance could be estimated using appropriate correlation equations.

Frequent toxicity from IV aminophylline infusions in critically ill patients. 1977

Use of recommended IV aminophylline dosage regimens in 48 older, acutely ill, hospitalized patients with chronic obstructive pulmonary disease (COPD) resulted in excessive plasma theophylline concentrations in 29 percent of these patients.

A mean dose of 0.89 mg/kg/hr produced a plasma concentration which ranged from 7 to 52 mcg/ml with a mean of 21.9 mcg/ml. Plasma theophylline concentration was determined spectrophotometrically from plasma samples drawn at least 12 hours after a loading dose and initiation of a constant infusion. Severity of toxicity strongly correlated with the plasma theophylline concentration in 18 patients. Nausea and/or vomiting preceded life-threatening drug-induced arrhythmias and seizures less than half the time. Tachycardia was found to be the most consistent symptom associated with toxicity. These patients had lower plasma clearances than otherwise healthy younger adult asthmatics and healthy volunteers. Toxicity and identifiable risk factors for excessive plasma levels strongly correlated with reduced plasma clearance. Dosage modifications based upon plasma clearances from COPD patients without concurrent functional abnormalities and those with liver dysfunction and cardiac decompensation ranged from 0.7 to 0.12 mg/kg/hr. This study clearly demonstrates the poor correlation between dose and plasma concentration and the strong relationship between toxicity and plasma concentration. These results as well as those previously reported mandate that the relatively simple, rapid and inexpensive theophylline plasma measurement be used in all patients receiving IV aminophylline for longer than 24 hours in order to prevent toxicity.

Awareness and use of caffeine by athletes competing at the 2005 Ironman Triathlon World Championships

This study assessed the knowledge, prevalence, and quantity of caffeine use by athletes competing at the 2005 Ironman Triathlon World Championships. Caffeine-related questionnaires were self-administered to 140 (105 male and 35 female, 40.3 +/- 10.7 y) athletes representing 16 countries. Fifty of these athletes further consented to immediate post-race blood samples for analysis of plasma caffeine and paraxanthine using high-performance liquid chromatography (HPLC). Seventy-two percent of 70 athletes correctly identified caffeine as being an unrestricted substance in triathlon. The majority of athletes [125 (89%)] were planning on using a caffeinated substance immediately prior to or throughout the race. Cola drinks (78%), caffeinated gels (42%), coffee (usually pre-race) (37%), energy drinks (13%), and NoDoz tablets (9%) were the most popular caffeinated choices. Mean +/- standard deviation (and range) post race plasma caffeine and paraxanthine levels were 22.3 +/- 20 micromol/L (1.7 to 98.4) and 9.4 +/- 6 micromol/L (1.8 to 28.9), respectively. Seven athletes (14%) finished with plasma caffeine levels > or = 40 micromol/L. Plasma values from elite athletes did not differ from age group competitors. Despite the prevalence of its consumption and the training experience of this athletic group, over one quarter of athletes remained either confused or uninformed about caffeine's legality. Levels of plasma caffeine taken immediately post race indicated that athletes typically finish with quantities of caffeine that have been shown to improve endurance performance (i.e., approximately 20 micromol/L or a dose of > or = 3 mg/kg body weight).

Acetic acid improves the sensitivity of theophylline analysis by gas chromatography–mass spectrometry

In the analysis of theophylline by gas chromatography-mass spectrometry (GC-MS), we found that the addition of acetic acid to the solvent (ethyl acetate) decreased the adsorption of theophylline to the glass wool packed into the inlet liner. The addition of acetic acid to ethyl acetate improved the sensitivity for theophylline (optimum concentration of 3%). This simple and sensitive method without derivatization can be applied to the quantification of theophylline in serum samples in clinical and toxicological practice.

Pharmacokinetics of Theophylline in Guinea Pig Tears

It is well recognized that the theophylline (TP) concentration in human tears correlates well with the free TP concentration in human plasma. However this correlation was found only in a very narrow range of concentrations of TP, and pharmacokinetic analysis of TP in tears has not been carried out for a wide range of concentrations of TP. The aims of this investigation were to develop a simple kinetic model for TP in guinea pig plasma (total [Cf+b] and free [Cf]), cerebrospinal fluid (CSF) [C](CSF) and tears [C](T), and to examine whether [Cf], [Cf+b] and [C](CSF) can be predicted from [C](T) using the resulting kinetic parameters. [Cf+b], [Cf], [C](CSF) and [C](T) were determined by GC/EI-SIM following bolus i.v. injection of TP in doses of 10, 50 and 100 mg/kg into guinea pigs. The wide range of concentrations of [Cf+b] could be quantitatively described by a two-compartment model with non-linear elimination kinetics and individual volume distribution of TP at each dose. [C](T) and [C](CSF) were analyzed using passive diffusion models with and without the pH-partition theory, respectively. The value of [Cf] could be predicted from the value of [C](T). Thus, the measurement of [C](T) which can be collected non-invasively would be a useful method for the therapeutic drug monitoring of TP.

[Drug therapy of asthma. Results of the 1998 German National Health Interview and Examination Survey]

The lifetime prevalence of bronchial asthma in adults is approximately 5%. Recommended drug therapy of this condition depends largely on its severity and varies from the on demand use of bronchodilators as a single measure up to the additional and sometimes permanent use of inhaled and/or systemic glucocorticoids. In this study, the prevalence and drug therapy of bronchial asthma were analysed in a representative sample of the resident population in Germany aged 18-79 years. We also report about health care utilization, like hospital stay, emergency treatments and use of ambulant medical care, and its associations with asthma medication. Of those study participants who affirmed a medical diagnosis of asthma, 17.3% used corticoid drugs continuously, 19.1% occasionally and 61.8% never. Use of medical services after an asthma attack was reported most often by those who took corticoid drugs regularly. Older people with asthma mostly used glucocorticoids regularly, while in very young patients the occasional use of corticoids was reported more often. When looking at the actual drug use (7 days before the examination) according to the drug usage questionnaire, anti-asthma drugs were mentioned as follows: 47.8% of persons with asthma, diagnosed during the last 4 weeks, used inhaled adrenergic drugs, 34.8% inhaled glucocorticoids, 2.1% systemic adrenergic drugs and 19.3% systemic theophyllines. The measured serum concentrations of theophylline were below 5 mg/l in 34.4%, between 5 and 8 mg/l in 28.1%, between 8 and 20 mg/l in 35.9% and somewhat over 20 mg/l in 1.6%. Our data suggest that especially young asthmatics may not be sufficiently treated with anti-inflammatory therapy, but further studies are needed. If such a deficit can be confirmed, measures for better adherence of therapy to existing guidelines should be considered. Our results, especially on serum concentrations of theophylline, suggest that therapeutic drug monitoring (TDM) of serum samples is not only an important tool in health surveys, but also suitable for increasing the safety and quality of drug treatment in asthmatics.

[Clinical review on patients who developed seizures during theophylline administration: relationships with seizure-predisposing factors]

OBJECTIVE

In recent years, attempts have been made to broadly deem seizures developing during theophylline administration as theophylline-related seizures. Consequently, a tendency to consider all the seizures attributable to theophylline has occurred. We investigated background factors in pediatric patients with seizures to examine the involvement of theophylline in the event.

METHODS

Of adverse events developing during theophylline administration which were reported by two theophylline preparation manufacturers between October 1987 and April 2004, we investigated underlying disease, regimen, outcome, and other items in 255 patients with seizures provoked by oral preparations and in 79 patients with seizures provoked by intravenous preparations.

RESULTS

The most predominant factors were represented by neurological predispositions, e.g., epilepsy, and by a history of fits prior to the onset of seizures in not less than two-thirds of pediatric patients with seizures who were receiving theophylline. Furthermore, not less than 90% of pediatric patients who remained with sequelae and who died had the factors. Our investigation revealed that the factors developed predominantly when the relevant patients presented fever, aged under 3 years and had history of seizures.

CONCLUSIONS

Therefore, we consider that advertence to this point is most important in administering theophylline safely.

Associations between CYP2E1 promoter polymorphisms and plasma 1,3-dimethyluric acid/theophylline ratios

OBJECTIVE

Theophylline is metabolized to 1,3-dimethyluric acid (1,3-DMU), 3-methylxanthine, and 1-methylxanthine by CYP1A2 and partly by CYP2E1. Because 1,3-DMU is the major metabolite of theophylline, the 1,3-DMU/theophylline ratio is viewed as a good indicator of theophylline metabolic clearance. Here, we investigated the associations between 1,3-DMU/theophylline ratios and genetic polymorphisms of CYP2E1 and CYP1A2.

METHODS

Polymerase chain reaction (PCR) and direct sequencing or PCR-restriction fragment length polymorphism (RFLP) were performed to analyze CYP2E1 and CYP1A2 promoter polymorphisms in 62 Korean asthma patients. Plasma theophylline and 1,3-DMU levels were measured by liquid chromatography-tandem mass spectrometry.

RESULTS

Eleven polymorphisms including Ins(96), -1566 T>A, -1515 T>G, -1414 C>T, -1295 G>C, -1055 C>T, -1027 T>C, -930 A>G, -807 T>C, -352 A>G, and -333 T>A were detected in the 5' flanking region of the CYP2E1 gene (numbering according to GenBank Accession number NT_017795). Of these, five single nucleotide polymorphisms (SNPs) (-1566 T>A, -1295 G>C, -1055 C>T, -1027 T>C, and -807 T>C) were closely linked. Another three polymorphisms (Ins(96,) -930 A>G, and -352 A>G) and two polymorphisms (-1515 T>G and -333 T>A) were also closely linked. The five closely linked polymorphisms were associated with significantly different 1,3-DMU/theophylline ratios between heterozygotes plus homozygotes of a rare allele (n=23, 0.0368+/-0.0171) and common allelic homozygotes (n=39, 0.0533+/-0.0343) (p=0.024 by Mann-Whitney U test). In the CYP1A2 gene, the -2964G>A polymorphisms exhibited a significant difference in 1,3-DMU/theophylline levels between heterozygotes plus homozygotes of a rare allele (n=30, 0.0406+/-0.0272) and homozygotes of a common allele (n=32, 0.0534+/-0.0316) (p=0.032).

CONCLUSION

We confirm that hydroxylation at the 8 position of theophylline (1,3-DMU) is significantly affected by genetic polymorphism in CYP2E1 in addition to CYP1A2.