Effect of cigarette smoke on UDP-glucuronosyltransferase activity and cytochrome P450 content in liver, lung and kidney microsomes in mice

Pharmacokinetic interactions between clozapine and valproic acid in patients with treatment-resistant schizophrenia: Does UGT polymorphism affect these drug interactions?

The combination of valproic acid (VPA) and clozapine (CLZ) is regularly prescribed for augmentation therapy in treatment resistant schizophrenia. The VPA has been shown to reduce norclozapine (NCLZ) plasma levels, but the mechanism of this interaction remains unknown. The aim of this study is to examine the differences between patients treated with CLZ and patients treated with CLZ plus VPA. For it, various factors have been evaluated. The study was based on plasma samples from CLZ and CLZ plus VPA treated patients (n = 61) subjected to routine therapeutic drug monitoring considering clinical data, smoking status, daily dose of CLZ and VPA, concomitant medications, albumin, and renal and hepatic function. Genotyping of polymorphisms of CYP1A2, CYP3A4/5, CYP2C19, ABCB1, UGT2B10 and CYP2C19 were performed by real time PCR. CYP2D6 were genotyped using competitive allele-specific PCR and by a long PCR based method. Plasma CLZ and NCLZ concentrations were measured by Liquid Chromatography-Tandem masses (LC-MS/MS) and plasma VPA by Ultraviolet-Visible (UV-vis) spectrophotometric immunoassay. The patients presented adequate CLZ levels in relation to the dose. However, NCLZ levels were excessively low and the CLZ/NCLZ ratio very high. Patients with UGT2B10 GT (rs61750900) genotype showed lower NCLZ plasma levels and C/D NCLZ, and higher CLZ/NCLZ ratio versus patients with UGT2B10 GG genotype. VPA, smoking, the presence of UGT2B10 GT genotype and having low albumin levels indicate that the CLZ/NCLZ ratio is affected, mostly coinciding with decreased NCLZ levels and possibly with an increased risk of neutropenia.

Effects of a novel UGT2B haplotype and UGT1A4*3 allele variants on glucuronidation of clozapine in vivo

BACKGROUND

Glucuronidation is an important metabolic pathway of clozapine (CLZ), but the impact of various uridine 5'diphospho-glucuronosyltransferases (UGT) polymorphisms on the exposure and metabolism of CLZ in vivo is unclear.

OBJECTIVE

The objective of this study was to investigate the impact of UGT2B haplotype and UGT1A4*3 allele variants on the formation of CLZ glucuronide metabolites (5N- and N+-glucuronide) and CLZ exposure in patients' serum after adjusting for sex, age and smoking habits.

METHODS

The study was based on serum samples from CLZ-treated patients (n=79) subjected to routine therapeutic drug monitoring (TDM) at Diakonhjemmet Hospital, Oslo, Norway. From the same patients the following UGT variants were genotyped using Real-Time PCR: UGT2B:GA haplotype (defined as UGT2B:GA; rs1513559A>G and rs416593T>A) and UGT1A4*3 (rs2011425T>G). Serum concentrations of CLZ 5N- and N+-glucuronide were measured by UPLC high-resolution mass spectrometry.

RESULTS

None of the genotypes had significant impact on CLZ exposure (p>0.05). However, compared to UGT2B:AT/AT and UGT1A4*1/*1, the 5N-glucuronide exposure was reduced in UGT2B:GA/GA carriers (-75%, p=0.03) while the exposure was non-significantly increased in UGT1A4*3 carriers (+100%, p=0.14), respectively. The N+-glucuronide exposure was unchanged in UGT1A4*3 vs noncarriers (p=0.28), but significantly reduced in heterozygous (-50%, p=0.016) and homozygous carriers (-70%, p=0.021) of UGT2B:GA compared to UGT2B:AT/AT carriers, respectively.

CONCLUSION

The UGT2B:GA and UGT1A4*3 variants had no impact on CLZ exposure, but were associated with differences and preferences in CLZ glucuronidation. The latter might be of potential relevance for CLZ tolerability, since levels of the N+-glucuronide metabolite may reflect the generation and trapping of reactive metabolites involved in CLZ-induced toxicity.

Multi-Omics Analysis of the Effects of Smoking on Human Tumors

Comprehensive studies on cancer patients with different smoking histories, including non-smokers, former smokers, and current smokers, remain elusive. Therefore, we conducted a multi-omics analysis to explore the effect of smoking history on cancer patients. Patients with smoking history were screened from The Cancer Genome Atlas database, and their multi-omics data and clinical information were downloaded. A total of 2,317 patients were included in this study, whereby current smokers presented the worst prognosis, followed by former smokers, while non-smokers showed the best prognosis. More importantly, smoking history was an independent prognosis factor. Patients with different smoking histories exhibited different immune content, and former smokers had the highest immune cells and tumor immune microenvironment. Smokers are under a higher incidence of genomic instability that can be reversed following smoking cessation in some changes. We also noted that smoking reduced the sensitivity of patients to chemotherapeutic drugs, whereas smoking cessation can reverse the situation. Competing endogenous RNA network revealed that mir-193b-3p, mir-301b, mir-205-5p, mir-132-3p, mir-212-3p, mir-1271-5p, and mir-137 may contribute significantly in tobacco-mediated tumor formation. We identified 11 methylation driver genes (including EIF5A2, GBP6, HGD, HS6ST1, ITGA5, NR2F2, PLS1, PPP1R18, PTHLH, SLC6A15, and YEATS2), and methylation modifications of some of these genes have not been reported to be associated with tumors. We constructed a 46-gene model that predicted overall survival with good predictive power. We next drew nomograms of each cancer type. Interestingly, calibration diagrams and concordance indexes are verified that the nomograms were highly accurate for the prognosis of patients. Meanwhile, we found that the 46-gene model has good applicability to the overall survival as well as to disease-specific survival and progression-free intervals. The results of this research provide new and valuable insights for the diagnosis, treatment, and follow-up of cancer patients with different smoking histories.

Coffee and cigarette smoking interactions with lamotrigine

The objective of this analysis was to determine possible interactions between lamotrigine (LTG) and coffee or cigarette use. As part of the statistical analysis of factors influencing LTG pharmacokinetics (PK) in the Equigen chronic dose study, we collected prospective data from enrolled patients on their use of coffee and cigarettes. Subjects were part of a crossover replication study of generic LTG products with rigorous blood sampling and were instructed to not change their typical consumption of these products for the duration of the study. A total of 35 subjects were enrolled, with 33 subjects having sufficient data for analysis. Higher consumption of coffee was associated with a significantly lower area under the curve (AUC) and maximum concentration (Cmax) of lamotrigine (LTG). Higher cigarette use did not result in a significant change in AUC or Cmax. Coffee, but not cigarette use, either induces LTG metabolism or inhibits LTG absorption.

No Impact of Smoking Status on Breast Cancer Tumor Infiltrating Lymphocytes, Response to Neoadjuvant Chemotherapy and Prognosis

Simple Summary

Tobacco use is associated with an increase in breast cancer mortality. Pathologic complete response (pCR) rate to neoadjuvant chemotherapy is influenced by tumor-infiltrating lymphocyte (TIL) levels and is associated with a better long-term survival outcome. The aim of this study was to evaluate the impact of smoking status on TIL levels, response to neoadjuvant chemotherapy and prognosis for breast cancer patients. We retrospectively assessed pre- and post-neoadjuvant chemotherapy tumor infiltrating lymphocyte (TILs) levels and pathological complete response (pCR) rates in a cohort of 956 specimens of breast cancer (BC) patients treated with neoadjuvant chemotherapy, according to their smoking status. To our knowledge, this is the largest cohort of BC patients used to study this topic so far. We found no impact of smoking status on tumor infiltrating lymphocyte levels, response to neoadjuvant chemotherapy and prognosis in the whole population and within each BC subtype.

Abstract

Tobacco use is associated with an increase in breast cancer (BC) mortality. Pathologic complete response (pCR) rate to neoadjuvant chemotherapy (NAC) is influenced by tumor-infiltrating lymphocyte (TIL) levels and is associated with a better long-term survival outcome. The aim of our study is to evaluate the impact of smoking status on TIL levels, response to NAC and prognosis for BC patients. We retrospectively evaluated pre- and post-NAC stromal and intra tumoral TIL levels and pCR rates on a cohort of T1-T3NxM0 BC patients treated with NAC between 2002 and 2012 at Institut Curie. Smoking status (current, ever, never smokers) was collected in clinical records. We analyzed the association between smoking status, TIL levels, pCR rates and survival outcomes among the whole population, and according to BC subtype. Nine hundred and fifty-six BC patients with available smoking status information were included in our analysis (current smokers, n = 179 (18.7%); ever smokers, n = 154 (16.1%) and never smokers, n = 623 (65.2%)). Median pre-NAC TIL levels, pCR rates, or median post-NAC TIL levels were not significantly different according to smoking status, neither in the whole population, nor in any BC subtype group. With a median follow-up of 101.4 months, relapse-free survival (RFS) and overall survival (OS) were not significantly different by smoking status. We did not find any significant effect of tobacco use on pre- and post-NAC TILs nor response to NAC. Though our data seem reassuring, BC treatment should still be considered as a window of opportunity to offer BC patients accurate smoking cessation interventions.

Smoking Reduces Plasma Bilirubin: Observational and Genetic Analyses in the Copenhagen General Population Study

INTRODUCTION

Observational studies have found lower concentrations of plasma bilirubin in current smokers compared with former and never smokers. However, whether there is a causal relationship between smoking and bilirubin is unknown. In a Mendelian randomization analysis, we tested the hypothesis that higher tobacco consumption is causally associated with lower concentrations of plasma bilirubin.

METHODS

We genotyped 103 557 individuals aged 20-100 years from the Copenhagen General Population Study for the CHRNA3 rs1051730 genotype, known to be associated with higher tobacco consumption. Tobacco consumption was defined as daily and cumulative tobacco consumption.

RESULTS

In observational multivariable-adjusted analyses, a 10 g/day higher daily tobacco consumption was associated with a 0.28 µmol/L (95% confidence interval = 0.20 to 0.35) lower concentration of plasma bilirubin in current smokers, and a 10 pack-year higher cumulative tobacco consumption was associated with a 0.19 µmol/L (0.17 to 0.21) lower concentration of plasma bilirubin in former and current smokers. Using the CHRNA3 rs1051730 genotype as a proxy for daily and cumulative tobacco consumption, the difference in plasma bilirubin per T-allele was -0.12 µmol/L (-0.23 to -0.002) in current smokers and -0.09 µmol/L (-0.15 to -0.01) in current and former smokers combined. Furthermore, observationally bilirubin concentrations increased with time from smoking cessation in former smokers.

CONCLUSION

Higher daily and cumulative tobacco consumption were associated with lower concentrations of plasma bilirubin in observational and genetic analyses, suggesting that the association is causal.

IMPLICATIONS

Our results are compatible with two possible interpretations of previous observational studies, either that bilirubin is a mediator of smoking-induced respiratory disease or that the association between plasma bilirubin and respiratory disease stems from residual confounding because of smoking. Future studies should examine whether bilirubin is a causal risk factor for respiratory disease, or merely a marker of smoking status.

Tail-phase safety, tolerability, and pharmacokinetics of long-acting injectable cabotegravir in HIV-uninfected adults: a secondary analysis of the HPTN 077 trial

BACKGROUND

Long-acting injectable cabotegravir is a novel integrase inhibitor currently in advanced clinical development for HIV prevention and treatment. We aimed to assess the terminal phase pharmacokinetics and safety of long-acting injectable cabotegravir in participants included in the HPTN 077 trial.

METHODS

HPTN 077 was a multicentre, double-blind, randomised, placebo-controlled phase 2a trial done at eight sites in Brazil, Malawi, South Africa, and the USA. Participants (aged 18-65 years), who were HIV-uninfected and at low-risk for HIV, were randomly assigned (3:1) to long-acting injectable cabotegravir (800 mg given three times at 12 week intervals or 600 mg given five times, administered at one 4 week interval, and every 8 weeks thereafter) or placebo. Participants were followed up to 76 weeks after final injection. In a prespecified analysis of secondary and exploratory outcomes, we assessed the safety, measured by the proportion of participants with grade 2 or worse adverse events, and pharmacokinetics, measured by apparent terminal phase half-life (t_1/2app) and estimated time to lower limit of quantification (LLOQ) of long-acting injectable cabotegravir during the injection phase (defined as the time between first injection and 12 weeks or 8 weeks after the last injection in cohort 1 or cohort 2 respectively) and tail phase (defined as the time between final injection and 52-76 weeks post-final injection). Safety was analysed in all participants who received at least one injection. Pharmacokinetic analyses included all participants who had received at least one injection and had at least three cabotegravir measurements higher than the LLOQ after the final injection. Pharmacokinetic outcomes were estimated using non-compartmental methods. The trial is completed, and was registered with ClinicalTrials.gov, NCT02178800.

FINDINGS

Between Feb 9, 2015, and May 27, 2016, 177 participants (134 participants in the cabotegravir group [74 participants in cohort 1; 60 participants in cohort 2] and 43 participants in the placebo group [25 participants in cohort 1; 18 participants in cohort 2) were enrolled and received at least one injection and thus were included in the safety analysis. The incidence of grade 2 or worse adverse events was significantly lower during the tail phase than the injection phase (p<0·0001). At 52-60 weeks after final injection, nine (23%) of 40 male participants had detectable cabotegravir concentrations and at week 76, four (13%) of 30 male participants had detectable cabotegravir concentrations compared with 52 (63%) of 82 female participants and 27 (42%) of 64 female participants at the same timepoints. The median time from the last injection to the time when cabotegravir concentration decreased below the LLOQ was 43·7 weeks (IQR 31·1-66·6; range 20·4-152·5) for male participants and 67·3 weeks (29·1-89·6; 17·7-225·5) for female participants (p=0·0003). t_1/2app was longer for female participants than male participants (geometric mean fold-change 1·33, 95% CI 1·06-1·68; p=0·014), and longer for participants with a high body-mass index (BMI) than those with a low BMI (1·31, 1·06-1·63; p=0·015).

INTERPRETATION

The clinical significance of the long pharmacokinetic tail of cabotegravir observed in female participants compared with male participants, and those with higher BMI compared with a lower BMI, need to be addressed in future trials.

FUNDING

National Institute of Allergy and Infectious Diseases.

Dolutegravir Population Pharmacokinetics in a Real-Life Cohort of People Living With HIV Infection: A Covariate Analysis

BACKGROUND

There are growing concerns about dolutegravir (DTG)-related neuropsychiatric adverse events and about differences in the characteristics of people living with HIV infection (PLWH) potentially associated with higher risks of said side effects. Several studies have shown that DTG was stopped more frequently among women, older PLWH, and PLWH who initiated abacavir (ABC) at the same time. This study aimed to clarify the factors affecting the pharmacokinetics (PKs) of DTG in a real-life cohort of PLWH using a population PK approach.

METHODS

The model-building strategy was based on a previously published model developed from premarketing trials (1-compartment model with first-order absorption and a lag time). Sparse therapeutic drug monitoring data were obtained from a real-life cohort of 279 PLWH, and population PK analysis was performed using Monolix software. A stepwise covariate model-building strategy was used to evaluate any relevant effects of age, body weight, gender, total bilirubin, smoking status, formulations of DTG, morning versus evening dosing, backbone therapy, and other comedications including CYP/UGT inducers/inhibitors.

RESULTS

For a typical 70-kg PLWH, the apparent clearance (CL/F) and apparent volume of distribution (V/F) were 0.748 L/h and 14.6 L, respectively. Of the demographic factors evaluated, body weight was a significant covariate for CL/F and for V/F. Smokers had a 17% higher CL/F relative to nonsmokers. Both strong enzyme inhibitors (eg, atazanavir) and inducers (eg, rifampicin) had marked effects on DTG exposure, with potential clinical implications. Ritonavir-boosted darunavir was found to moderately increase clearance of DTG by 23%. No significant effect of ABC-based backbone therapy was observed on the PK parameters of DTG.

CONCLUSIONS

Our results did not support the hypothesis that ABC, by competing with the DTG metabolic pathway, may significantly increase DTG exposure leading to potential drug toxicity.

Investigating the clinical factors and comedications associated with circulating levels of atorvastatin and its major metabolites in secondary prevention

Aims The lipid-lowering drug, atorvastatin (ATV), is 1 of the most commonly prescribed medications worldwide. The aim of this study was to comprehensively investigate and characterise the clinical factors and comedications associated with circulating levels of ATV and its metabolites in secondary prevention clinical practice. Methods The plasma concentrations of ATV, 2-hydroxy (2-OH) ATV, ATV lactone (ATV L) and 2-OH ATV L were determined in patients 1 month after hospitalisation for a non-ST elevation acute coronary syndrome. Factors were identified using all subsets multivariable regression and model averaging with the Bayesian information criterion. Exploratory genotype-stratified analyses were conducted using ABCG2 rs2231142 (Q141K) and CYP2C19 metaboliser status to further investigate novel associations. Results A total of 571 patients were included; 534 and 37 were taking ATV 80 mg and 40 mg daily, respectively. Clinical factors associated with ATV and/or its metabolite levels included age, sex, body mass index and CYP3A inhibiting comedications. Smoking was newly associated with increased ATV lactonisation and reduced hydroxylation. Proton pump inhibitors (PPIs) and loop diuretics were newly associated with modestly increased levels of ATV (14% and 38%, respectively) and its metabolites. An interaction between PPIs and CYP2C19 metaboliser status on exposure to specific ATV analytes (e.g. interaction P = .0071 for 2-OH ATV L) was observed. Overall model R² values were 0.14-0.24.ConclusionMultiple factors were associated with circulating ATV and metabolite levels, including novel associations with smoking and drug-drug(-gene) interactions involving PPIs and loop diuretics. Further investigations are needed to identify additional factors that influence ATV exposure.

Tobacco smoking and its drug interactions with comedications involving CYP and UGT enzymes and nicotine

Tobacco smoking is a global public health threat causing several illnesses including cardiovascular disease (Myocardial infarction), cerebrovascular disease (Stroke), peripheral vascular disease (Claudication), chronic obstructive pulmonary disease, asthma, reduced female infertility, sexual dysfunction in men, different types of cancer and many other diseases. It has been estimated in 2015 that approximately 1.3 billion people smoke, around the globe. Use of medications among smokers is more common, nowadays. This review is aimed to identify the medications affected by smoking, involving Cytochrome P450 (CYP) and uridine diphosphate-glucuronosyltransferases (UGTs) enzymes and Nicotine. Polycyclic aromatic hydrocarbons (PAHs) of tobacco smoke have been associated with the induction of CYP enzymes such as CYP1A1, CYP1A2 and possibly CYP2E1 and UGT enzymes. The drugs metabolized by CYP1A1, CYP1A2, CYP2E1 and UGT enzymes might be affected by tobacco smoking and the smokers taking medications metabolized by those enzymes, may need higher doses due to decreased plasma concentrations through enhanced induction by PAHs of tobacco smoke. The prescribers and the pharmacists are required to be aware of medications affected by tobacco smoking to prevent the toxicity-associated complications during smoking cessation.

CYP1A1 and 1B1-mediated metabolic pathways of dolutegravir, an HIV integrase inhibitor

Dolutegravir (DTG), a potent integrase inhibitor, is part of a recommended initial regimen for the treatment of human immunodeficiency virus (HIV). Prior reports demonstrated that the clearance of DTG was higher in current smokers than non-smokers, but the mechanism remains unclear. Using a metabolomic approach, M4 (an aldehyde) was identified as a novel metabolite of DTG. In addition, the formation of M4 was found to be mediated by cytochrome P450 (CYP) 1A1 and 1B1, the enzymes that can be highly induced by cigarette smoking. CYP1A1 and 1B1 were also identified as the major enzymes contributing to the formation of M1 (an N-dealkylated metabolite of DTG) and M5 (an aldehyde). Furthermore, the production of M1 and M4 was significantly increased in the lung of mice treated with 2,3,7,8-tetrachlorodibenzo-p-dioxin, an inducer of CYP1A1 and 1B1. In summary, the current study uncovered the CYP1A1 and 1B1-mediated metabolic pathways of DTG. These data suggest that persons with HIV infection receiving DTG should be cautious to cigarettes, and drugs, or exposure to environmental chemicals that induce CYP1A1 and 1B1.

Tandem mass tags labeled quantitative proteomics to study the effect of tobacco smoke exposure on the rat lung

BACKGROUND

The causal link between tobacco smoke exposure (TSE) and numerous severe respiratory system diseases (RSD), including chronic bronchitis, chronic obstructive pulmonary disease, and lung cancer, is well established. However, the pathogenesis of TSE-induced RSD remains incompletely understood. This research aims to detect the pathogenetic mechanisms and potential therapeutic targets of TSE-induced RSD.

METHODS

This study employed TSE model which rats were exposed to a concentration of 60% tobacco smoke in a toxicant exposure system for four weeks. Tandem mass tags (TMT) labeled quantitative proteomics combined with off-line high pH reversed-phase fractionation, and nano-liquid chromatography-mass spectrometry method (off-line high pH RPF-nano-LC-MS/MS) were adopted to detect differentially expressed proteins (DEPs) in the lung tissues of the TSE model rats and to compare them with those in control. The accuracy of the results was verified by western blot.

RESULTS

Compared with the control group, 33 proteins in the TSE model group's lung tissues showed significant differential expression. Analysis based on the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways indicated that, several biological pathways, such as the steroid biosynthesis pathway, were involved and played significant roles in the pathogenesis of the experimental group's TSE.

CONCLUSIONS

These findings make a crucial contribution to the search for a comprehensive understanding of TSE-induced RSD's pathogenesis, and furthermore provide guidance for the diagnosis and treatment of TSE-induced RSD.

Relationship between serum bilirubin levels and cardiovascular disease

We tested the hypothesis that higher levels of bilirubin, a bile pigment with antioxidant properties, are associated with a decreased risk of cardiovascular disease (CVD). This study analyzed data from the Korean Health and Genome Study to examine the association between serum total bilirubin (TB) on CVD and CVD death. Serum TB was measured in a total of 8,844 subjects (4,196 males and 4,648 females) and evaluated for the development of new onset CVD from 2001 to 2012 (mean 8.1 years of follow-up). During the follow-up period, 689 cases of incident CVD (7.8%) were identified, and the prevalence of metabolic syndrome (MetS) at baseline was 26.1%. The prevalence of MetS decreased across bilirubin tertile categories. In addition to MetS itself, individual components of MetS significantly decreased with increased bilirubin tertiles. Moreover, the incidence of CVD decreased across bilirubin tertile categories. The hazard ratios (HRs) for developing coronary heart disease (CHD, HR 0.769, 95% CI 0.655–1.000) and CVD death (HR 0.513, 95% CI 0.267–0.985) was significantly lower in the highest tertile group (> 0.63 mg/dL) in comparison to the lowest tertile group (< 0.44 mg/dL) after adjusting for all confounding variables. In the present longitudinal study, a significant negative relationship was demonstrated between baseline bilirubin levels and incident CHD and CVD death.

Evaluation of genetic effect of NOS3 and G×E interaction on the variability of serum bilirubin in a Han Chinese population

Bilirubin was shown to be related to the generation and functional exertion of endothelial nitric oxide synthase (eNOS) whilst the genetic effect of NOS3 on bilirubin variability was rarely reported. Herein we assessed the associations of three single nucleotide polymorphisms (SNPs) of NOS3 (rs4496877, rs1808593, and rs3918186) with bilirubin elevation in 2077 adults. The results showed that rs1808593 was significantly associated with bilirubin elevation, and odds ratios (ORs) of dominant model for the elevation of total bilirubin (TBIL), direct bilirubin (DBIL), and indirect bilirubin (IDBIL) were 0.837, 0.821 and 0.754, respectively (P < 0.05 for all). Stratification analysis indicated that rs3918186 was significantly associated with the elevation of TBIL and IDBIL in the males, and ORs of dominant model were 1.505 and 1.440 with P < 0.05 for all. In the smoking group, significant associations of rs4496877, rs1808593, and rs3918186 with TBIL elevation were observed, and ORs of dominant model were 1.739, 0.758 and 1.626 (P < 0.05 for all). rs4496877 and rs3918186 were both associated with TBIL elevation in the drinking group, and ORs were 1.557 and 1.769 with P < 0.05 for all. In the ≥55 year-old group, rs4496877 and rs1808593 were significantly associated with DBIL and IDBIL elevations, and ORs were 1.340 and 0.790 (P < 0.05). Meanwhile, rs4496877, rs1808593, rs3918186, smoking, and drinking were shown to have a notable interaction effects on the TBIL elevation. Our findings supported that NOS3 harbors the genetic susceptibility to the bilirubin elevation. Age, gender, smoking, and drinking could be involved in the genetic modification of NOS3 on the bilirubin variability.

UPLC-MS/MS method for the determination of tobacco-specific biomarker NNAL, tamoxifen and its main metabolites in rat plasma

Cigarette smoke is known to interact with tamoxifen-metabolizing enzymes and transporters and potentially affect its treatment outcome. 4-(N-nitrosomethylamino)-1-(3-pyridyl)-1-butanol (NNAL) is an important metabolite of 4-(methylnitro-samino)-1-(3-pyridyl)-1-butanone (NNK) because it is frequently used as a biomarker to assess human smoke exposure. In order to study the potential pharmacokinetic interaction between cigarette smoke and tamoxifen in rats a UPLC-MS/MS method for the simultaneous determination of NNAL and tamoxifen along with its metabolites in rat plasma has been developed and validated. Analytes were extracted with methanol and separated on a HSS T3 column by a gradient elution with the mobile phase consisting of acetonitrile and water. The lower limits of quantitation ranged from 0.05 to 0.62 ng/mL. Precisions showed RSD <15.8% and accuracy in the range 80.6-116.0%. Mean analyte recoveries ranged from 76.9 to 108.4%. The method was successfully applied to study the effects of cigarette smoke condensate (CSC), NNK and benzo(a)pyrene pre-treatment on the pharmacokinetics of tamoxifen and its metabolites in rats. Significant effects of CSC, NNK, benzo(a)pyrene were observed on pharmacokinetics of tamoxifen and its metabolites. We also found that plasma NNAL levels are statistically significant correlated with plasma 4-hydroxy-tamoxifen and endoxifen.

Metabolism and Bioactivation of Fluorochloridone, a Novel Selective Herbicide, in Vivo and in Vitro

Fluorochloridone (FLC) is a herbicide used worldwide that is thought to be safe. However, due to its potential genotoxicity, cytotoxicity, and even systematic toxicity, there are increasing concerns about human exposure to this compound. Thus, the metabolism and bioactivation of FLC was investigated. After oral administration to mice, 27 metabolites were identified by ultrahigh performance liquid chromatography-electrospray ionization-quadrupole time-of-flight-mass spectrometry and with further structural identification by nuclear magnetic resonance spectroscopy. Hydroxylation and oxidative dechlorination were the major phase I pathways, while glutathione (GSH) and N-acetylcysteine conjugations were two major phase II pathways, indicating the formation of a reactive intermediate. In vitro microsomal and cytosolic studies revealed that a GSH conjugate (M13) was the predominant metabolite of FLC formed through a nucleophilic SN2 substitution of 3-Cl by GSH; this pathway is NADPH independent and accelerated by glutathione S-transferase (GST). Further, a kinetic study showed that M13 formation in both human liver microsomes and cytosols obeyed typical Michaelis-Menten kinetics. The maximum clearance (Vmax/Km) of GSH conjugation in human liver microsomes was approximately 5.5-fold higher than human liver cytosol, thus implying that microsomal GST was mainly responsible for M13 formation. These findings are important for understanding the potential hazard of human exposure to FLC.

Influence of Occupational and Environmental Exposure to Low Concentrations of Polychlorobiphenyls and a Smoking Habit on the Urinary Excretion of Corticosteroid Hormones

The effects of occupational exposure to low concentrations of polychlorobiphenyls (PCBs) on the urinary excretion of corticosteroid hormones were evaluated, taking into account the influence of cigarette smoking. The study included 26 males working as electrical maintenance staff in a steel factory, previously exposed to a mixture of PCBs (exposed workers), and 30 male workers with no occupational exposure to PCBs (controls). Serum PCBs (33 congeners), urinary 17-hydroxycorticosteroids, 17-ketosteroids (KS) and pregnanes, and their respective glucuronidated and sulfonated compounds, were determined for each subject. PCBs were significantly higher in the exposed workers than controls, and were correlated with age. Both the urinary concentrations of the total 17-KS and pregnanes, and those of some single steroids and their glucuronidated compounds, were significantly lower in the exposed workers than controls, but higher in smokers than the non-smokers + ex-smokers. Two-way analysis of variance showed a negative association between serum PCBs and both total glucuronidated 17-KS and total and glucuronidated pregnanes, and a positive association between cigarette smoking and both total and glucuronidated 17-KS. PCBs seem to act as endocrine disruptors by reducing the urinary excretion of corticosteroid hormones, particularly of the glucuronidated fraction. Cigarette smoking could boost these effects of PCBs in smokers.

Drugs and Diseases Interacting with Cigarette Smoking in US Prescription Drug Labelling

The US Food and Drug Administration (FDA) draft guidance for industry on drug interaction studies recommends, but does not mandate, that both cigarette smokers and non-smokers can be used to study drug metabolism in clinical trials, and that important results related to smoking should be included in drug labelling to guide medication usage. This study aimed to provide a comprehensive review of drugs or diseases interacting with smoking, as presented in all US drug labelling. The 62,857 drug labels deposited in the FDA Online Label Repository were searched using the keywords 'smoke', 'smoker(s)', 'smoking', 'tobacco' and 'cigarette(s)' on 19 June 2014. The resultant records were refined to include only human prescription drug labelling, for manual examination. For 188 single-active-ingredient drugs and 36 multiple-active-ingredient drugs, the labelling was found to contain smoking-related information. The pharmacokinetics of 29 and 21 single-active-ingredient drugs were affected and unaffected, respectively, by smoking. For the remaining drugs, the provided information related to smoking affecting efficacy, safety or diseases but not pharmacokinetics. Depending on the nature of specific drugs, the perturbation in pharmacokinetic parameters in smokers ranged from 13 to 500%, in comparison with non-smokers. Dosage modifications in smokers are necessary for four drugs and may be necessary for six drugs, but are unnecessary for seven drugs although the pharmacokinetic parameters of four of them are affected by smoking. Cigarette smoking is a risk factor for 16 types of diseases or adverse drug reactions. For one single-active-ingredient contraceptive drug and 10 multiple-active-ingredient contraceptive drugs, a black box warning (the FDA's strongest safety warning) is included in the labelling for increased risks of heart attacks and strokes in female smokers, and "women are strongly advised not to smoke" when using these drugs. This study presents the first comprehensive overview of cigarette smoking interacting with drugs and/or diseases, as presented in US drug labelling.

Active and Passive Smoking and Serum Total Bilirubin in a Rural Korean Population

INTRODUCTION

Serum bilirubin is an endogenous antioxidant biomarker and its low level is a potential risk factor for smoking related health disorders. This study investigated the association of cigarette smoke with serum total bilirubin among Koreans.

METHODS

Between 2006 and 2011, we examined 4899 Korean adults living in a rural community. After excluding 38 participants with serum bilirubin more than 2mg/dL, 75 participants who did not report their smoking status or who had liver or bile duct disorders, and 711 participants with liver enzymes exceeding the upper reference values, we performed a cross-sectional analysis on 4075 participants. Participants were classified into four groups: never-smokers without secondhand smoke exposure (SHSE), never-smokers with SHSE, former smokers, and active smokers. Serum total bilirubin concentration was measured using the enzyme method.

RESULTS

Compared to never-smokers without SHSE, never-smokers with SHSE (β = -0.025 mg/dL), former smokers (β = -0.049 mg/dL), and active smokers (β = -0.149 mg/dL) had significantly lower serum bilirubin even after adjusting for demographic factors, study year, alanine aminotransferase, gamma-glutamyl transferase, hemoglobin, lifestyle factors, and chronic diseases. A sex-stratified analysis indicated that for men, former smokers and active smokers were significantly associated with having lower bilirubin when compared to never-smokers without SHSE. However, for women, never-smokers with SHSE and active smokers were significantly associated with having lower bilirubin when compared to never-smokers without SHSE.

CONCLUSION

Our findings suggest that both active and passive cigarette smoking are associated with low serum bilirubin among Korean adults.

IMPLICATIONS

Our results suggest that not only active smoking but also passive smoking including SHSE can have an influence on decreasing serum bilirubin levels. With this different point of view, our study supports efforts to create smoke-free environments in order to foster more favorable serum bilirubin profiles, which may improve endothelial function and reduce the risk of cardiovascular disease.

Bilirubin treatment suppresses pulmonary inflammation in a rat model of smoke-induced emphysema

BACKGROUND

Cigarette smoking is a significant risk factor for emphysema, which is characterized by airway inflammation and oxidative damage.

OBJECTIVES

To assess the capacity of bilirubin to protect against smoke-induced emphysema.

METHODS

Smoking status and bilirubin levels were recorded in 58 patients with chronic obstructive pulmonary diseases (COPD) and 71 non-COPD participants. The impact of smoking on serum bilirubin levels and exogenous bilirubin (20 mg/kg/day) on pulmonary injury was assessed in a rat model of smoking-induced emphysema. At sacrifice lung histology, airway leukocyte accumulation and cytokine and chemokine levels in serum, bronchoalveolar lavage fluid (BALF) and lung were analyzed. Oxidative lipid damage and anti-oxidative components was assessed by measuring malondialdehyde, superoxide dismutase (SOD) activity and glutathione.

RESULTS

Total serum bilirubin levels were lower in smokers with or without COPD than non-smoking patients without COPD (P < 0.05). Indirect serum bilirubin levels were lower in COPD patients than patients without COPD (P < 0.05). In rats, cigarette smoke reduced serum total and indirect bilirubin levels. Administration of bilirubin reduced mean linear intercept and mean alveoli area, increased mean alveoli number, reduced macrophage, neutrophil and TNF-α content of BALF, and increased BALF and serum IL-10 level, but lowered local and systemic CCL2, CXCL2, CXCL8 and IL-17 levels. Bilirubin suppressed the smoke-induced systemic and regional oxidative lipid damage associated with increased SOD activity.

CONCLUSION

Bilirubin attenuated smoking-induced pulmonary injury by suppressing inflammatory cell recruitment and pro-inflammatory cytokine secretion, increasing anti-inflammatory cytokine levels, and anti-oxidant SOD activity in a rat model of smoke-induced emphysema.

Opioid Analgesics and Nicotine: More Than Blowing Smoke

Practitioners are highly likely to encounter patients with concurrent use of nicotine products and opioid analgesics. Smokers present with more severe and extended chronic pain outcomes and have a higher frequency of prescription opioid use. Current tobacco smoking is a strong predictor of risk for nonmedical use of prescription opioids. Opioid and nicotinic-cholinergic neurotransmitter systems interact in important ways to modulate opioid and nicotine effects: dopamine release induced by nicotine is dependent on facilitation by the opioid system, and the nicotinic-acetylcholine system modulates self-administration of several classes of abused drugs-including opioids. Nicotine can serve as a prime for the use of other drugs, which in the case of the opioid system may be bidirectional. Opioids and compounds in tobacco, including nicotine, are metabolized by the cytochrome P450 enzyme system, but the metabolism of opioids and tobacco products can be complicated. Accordingly, drug interactions are possible but not always clear. Because of these issues, asking about nicotine use in patients taking opioids for pain is recommended. When assessing patient tobacco use, practitioners should also obtain information on products other than cigarettes, such as cigars, pipes, smokeless tobacco, and electronic nicotine delivery systems (ENDS, or e-cigarettes). There are multiple forms of behavioral therapy and pharmacotherapy available to assist patients with smoking cessation, and opioid agonist maintenance and pain clinics represent underutilized opportunities for nicotine intervention programs.

Effects of cigarette smoking on metabolism and effectiveness of systemic therapy for lung cancer

INTRODUCTION

Cigarette smoke associated polycyclic aromatic hydrocarbons can induce key drug-metabolizing enzymes of cytochrome P450 and isoforms of the glucuronyl transferases families. These enzymes metabolize several systemic therapies for lung cancer. Induction of these enzymes may lead to accelerated clearance with resultant impact on systemic therapy efficacy and toxicity in smokers compared with nonsmokers. This article reviews published literature regarding the influence of smoking as it relates to alteration of metabolism of systemic therapy in lung cancer.

METHODS

A structured search of the National Library of Medicine's PubMed/MEDLINE identified relevant articles. Data were abstracted and analyzed to summarize the findings.

RESULTS

Studies that analyzed pharmacokinetic data were prospective. Smokers receiving erlotinib exhibited rapid clearance, requiring a higher dose to reach equivalent systemic exposure compared with nonsmokers. Smokers receiving irinotecan also demonstrated increased clearance and lower systemic exposure. There was no difference in clearance of paclitaxel or docetaxel in smokers. Chemotherapy-associated neutropenia was worse in nonsmokers compared with smokers in patients treated with paclitaxel, docetaxel, irinotecan, and gemcitabine.

CONCLUSIONS

Systemic therapy for lung cancer has a narrow therapeutic index such that small changes in plasma concentrations or exposure in smokers may result in suboptimal therapy and poor outcomes. Smoking cessation must be emphasized at each clinical visit. However, prospective trials should take into consideration the effects of smoking history on drug pharmacokinetics and efficacy. The metabolizing enzyme phenotype in smokers may require individualized dose algorithms for specific agents.

Dopamine function in cigarette smokers: an [¹⁸F]-DOPA PET study

Tobacco addiction is a global public health problem. Addiction to tobacco is thought to involve the effects of nicotine on the dopaminergic system. Only one study has previously investigated dopamine synthesis capacity in cigarette smokers. This study, exclusively in male volunteers, reported increased dopamine synthesis capacity in heavy smokers compared with non-smokers. We sought to determine whether dopamine synthesis capacity was elevated in a larger sample of cigarette smokers that included females. Dopamine synthesis capacity was measured in 15 daily moderate smokers with 15 sex- and age-matched control subjects who had never smoked tobacco. Dopamine synthesis capacity (indexed as the influx rate constant K(i)(cer)) was measured with positron emission tomography and 3,4-dihydroxy-6-[(18)F]-fluoro-l-phenylalanine. There was no significant group difference in dopamine synthesis capacity between smokers and non-smoker controls in the whole striatum (t28=0.64, p=0.53) or any of its functional subdivisions. In smokers, there were no significant relationships between the number of cigarettes smoked per day and dopamine synthesis capacity in the whole striatum (r=-0.23, p=0.41) or any striatal subdivision. These findings indicate that moderate smoking is not associated with altered striatal dopamine synthesis capacity.

Serum total bilirubin concentrations are inversely associated with total white blood cell counts in an adult population

BACKGROUND

Several studies have shown that serum bilirubin has a protective effect against cardiovascular disease and that inflammation plays an important role in its pathogenesis. This cross-sectional study investigated whether there was an association between blood total white blood cell count, a simple indicator of inflammation, and serum total bilirubin concentration in a cohort of an adult population in Taiwan.

METHODS

A total of 2458 apparently healthy adults (1246 men and 1212 women) who attended health examination at a medical centre in central Taiwan were enrolled. We collected anthropometric measurements, fasting blood test results, lifestyle habits and medical history.

RESULTS

Total white blood cell counts decreased progressively when the concentrations of total bilirubin increased as demonstrated in the total bilirubin quartiles. Both total bilirubin concentrations and total white blood cell counts showed significant correlations with the components of metabolic syndrome, including triglyceride and high-density lipoprotein cholesterol concentrations. Multivariate linear regression analysis revealed that, for both genders, total bilirubin showed an independent negative correlation with total white blood cell count after adjusting for conventional cardiovascular risk factors.

CONCLUSIONS

Higher serum total bilirubin concentrations within the reference range were associated with lower blood total white blood cell counts, regardless of other classical cardiovascular risk factors.

UGT2B gene expression analysis in multiple tobacco carcinogen-targeted tissues

The UDP-glucuronosyltransferase (UGT) 2B subfamily of enzymes plays an important role in the metabolism of numerous endogenous and exogenous compounds, including various carcinogens present in tobacco smoke. The goal of the present study was to examine the levels of expression of individual UGT2B genes in various tissues that are targets for tobacco carcinogenesis. Using MT-ATP6 as the experimentally validated housekeeping gene, the highest extrahepatic expression of UGT2B genes was observed in human tonsil, with UGT2B expression levels similar to that observed in human liver. UGT2B17 exhibited high relative expression in most tissues examined, including lung, most tissues of the aerodigestive tract, and pancreas. UGT2B7 expression was highest in pancreas but low or undetectable in most other tissues examined. UGT2B10 expression was high in both tonsil and tongue. There was wide variability between individuals in the magnitude of expression in each tissue site, and there were strong correlations between UGT2B expression levels in different individuals within many of the tissue sites, suggesting coordinated regulation of UGT2B gene expression in extrahepatic tissues. In the liver, UGTs 2B4, 2B7, 2B10, and 2B15 were significantly correlated with each other (all r(2) > 0.70, P < 0.0001). In all examined tissues of the aerodigestive tract, UGTs 2B10, 2B11, and 2B17 exhibited a strong correlation with each other (all r(2) > 0.75, P < 0.05). UGTs 2B7 and 2B10 exhibited a strong inverse correlation in the pancreas (r(2) = -0.95, P < 0.01). These data suggest that specific UGT2B enzymes important in tobacco carcinogen metabolism are expressed and coordinately regulated in various target sites for tobacco-related cancers.

Metabolism and bioactivation of famitinib, a novel inhibitor of receptor tyrosine kinase, in cancer patients

BACKGROUND AND PURPOSE

Famitinib is a novel multi-targeted receptor tyrosine kinase inhibitor under development for cancer treatment. This study aims to characterize the metabolic and bioactivation pathways of famitinib.

EXPERIMENTAL APPROACH

The metabolites in human plasma, urine and feces were identified via ultra-high performance liquid chromatography-quadrupole-time of flight-mass spectrometry and confirmed using synthetic standards. Biotransformation and bioactivation mechanisms were investigated using microsomes, recombinant metabolic enzymes and hepatocytes.

KEY RESULTS

Famitinib was extensively metabolized after repeated oral administrations. Unchanged famitinib was the major circulating material, followed by N-desethylfaminitib (M3), whose steady-state exposure represented 7.2 to 7.5% that of the parent drug. Metabolites in the excreta were mainly from oxidative deamination (M1), N-desethylation (M3), oxidative defluorination (M7), indolylidene hydroxylation (M9-1 and M9-5) and secondary phase-II conjugations. CYP3A4/5 was the major contributor to M3 formation, CYP3A4/5 and aldehyde dehydrogenase to M1 formation and CYP1A1/2 to M7, M9-1 and M9-5 formations. Minor cysteine conjugates were observed in the plasma, urine and feces, implying the formation of reactive intermediate(s). In vitro microsomal studies proved that famitinib was bioactivated through epoxidation at indolylidene by CYP1A1/2 and spontaneously defluorinated rearrangement to afford a quinone-imine species. A correlation between famitinib hepatotoxicity and its bioactivation was observed in the primary human hepatocytes.

CONCLUSION AND IMPLICATIONS

Famitinib is well absorbed and extensively metabolized in cancer patients. Multiple enzymes, mainly CYP3A4/5 and CYP1A1/2, are involved in famitinib metabolic clearance. The quinone-imine intermediate formed through bioactivation may be associated with famitinib hepatotoxicity. Co-administered CYP1A1/2 inducers or inhibitors may potentiate or suppress its hepatotoxicity.

Interception of benzo[a]pyrene-7,8-dione by UDP glucuronosyltransferases (UGTs) in human lung cells

Polycyclic aromatic hydrocarbons (PAHs) are environmental and tobacco carcinogens. Proximate carcinogenic PAH trans-dihydrodiols are activated by human aldo-keto reductases (AKRs) to yield electrophilic and redox-active o-quinones. Interconversion among benzo[a]pyrene (B[a]P)-7,8-dione, a representative PAH o-quinone, and its corresponding catechol generates a futile redox-cycle with the concomitant production of reactive oxygen species (ROS). We investigated whether glucuronidation of B[a]P-7,8-catechol by human UDP glucuronosyltransferases (UGTs) could intercept the catechol in three different human lung cells. RT-PCR showed that UGT1A1, 1A3, and 2B7 were only expressed in human lung adenocarcinoma A549 cells. The corresponding recombinant UGTs were examined for their kinetic constants and product profile using B[a]P-7,8-catechol as a substrate. B[a]P-7,8-dione was reduced to B[a]P-7,8-catechol by dithiothreitol under anaerobic conditions and then further glucuronidated by the UGTs in the presence of uridine-5′-diphosphoglucuronic acid as a glucuronic acid group donor. UGT1A1 catalyzed the glucuronidation of B[a]P-7,8-catechol and generated two isomeric O-monoglucuronsyl-B[a]P-7,8-catechol products that were identified by RP-HPLC and by LC-MS/MS. By contrast, UGT1A3 and 2B7 catalyzed the formation of only one monoglucuronide, which was identical to that formed in A549 cells. The kinetic profiles of three UGTs followed Michaelis–Menten kinetics. On the basis of the expression levels of UGT1A3 and UGT2B7 and the observation that a single monoglucuronide was produced in A549 cells, we suggest that the major UGT isoforms in A549 cells that can intercept B[a]P-7,8-catechol are UGT1A3 and 2B7.

Relationships between serum total bilirubin levels and metabolic syndrome in Korean adults

BACKGROUND AND AIMS

Metabolic syndrome (MS) is associated with insulin resistance in all parts of its natural history, which is accompanied by oxidative stress. Bilirubin is a potent endogenous antioxidant and cytoprotectant. The current study was performed to identify the major predictors of the total bilirubin level and to assess the relationships between the total bilirubin levels and MS in Korean adults.

METHODS AND RESULTS

This is a cross-sectional study involving 12342 adults aged 20 years and over who visited a Health Promotion Center. Physical examinations and laboratory tests including total and direct bilirubin levels were performed. MS was defined based on the modified NCEP-ATP III definition and the determinations of the Korean Society for the Study of Obesity. The results showed that hemoglobin had the strongest influence on the total bilirubin levels after adjusting for age, gender, and all other variables. The high-bilirubin group (≥15.4 μmol/L in males and ≥12.1 μmol/L in females) was associated with significantly decreased odds of MS compared to the low-bilirubin group (OR 0.74 [95% CI 0.64-0.86]). High levels of bilirubin also were negatively associated with abdominal obesity and hypertriglyceridemia. The total bilirubin levels decreased with an increase in the number of MS components after adjustment for all covariates.

CONCLUSION

Within the physiological range, the serum total bilirubin level was negatively associated with the MS in subjects without overt metabolic or cardiovascular diseases. This may be partially due to the negative association between the total bilirubin level and abdominal obesity and hypertriglyceridemia.

Expression of UDP-glucuronosyltransferase 1A4 in human placenta at term

The placenta contains a large variety of metabolizing enzymes, among them UDP-glucuronosyltransferase (UGT). Several UGT2B isozymes have so far been detected in human placenta, but little is known on placental expression of UGT1A isozymes. The antiepileptic drug lamotrigine (LTG) is a UGT1A4-substrate, and its serum concentration falls by over 50% during pregnancy, leading to impaired seizure control. The placenta may be involved in this. Microsomes from term placentas of 4 LTG-users and 10 healthy control subjects were prepared. Western blot analysis detected UGT1A proteins in all placentas. The presence of UGT1A4 in placenta from LTG users was confirmed with UGT1A4 commercial standard and a specific UGT1A4 primary antibody. Since LTG is primarily metabolized by UGT1A4 and this isozyme is shown to be present in placenta at term, it may be hypothesized that the placenta is involved in the fall of LTG serum concentrations during pregnancy.

The bilirubin level is negatively correlated with the incidence of hypertension in normotensive Korean population

Reactive oxygen species have been known to be an important factor in the pathogenesis of hypertension. Bilirubin, one of the metabolites of heme degraded by heme oxygenase, is a potent anti-oxidant. We verified the effect of serum bilirubin level on the incidence of hypertension in normotensive subjects. We grouped 1,208 normotensive subjects by the criterion of the highest quintile value of serum bilirubin, 1.1 mg/dL. The incidence of hypertension was higher in group 1 with bilirubin less than 1.1 mg/dL than in group 2 with bilirubin 1.1 mg/dL or more (186/908 vs. 43/300, p=0.018). The relative risk for hypertension was 0.71 (95% confidence interval, 0.51-0.99), p=0.048 in group 2 compared to group 1 by Cox's proportional hazard model. Among the groups stratified by gender, smoking, and liver function status, the group 2 showed a lower risk of hypertension in females and in non-smokers. In conclusion, a mild increase within the physiological range of serum bilirubin concentration was negatively correlated with the incidence of hypertension. The effect of bilirubin on the development of hypertension was more evident in females and in non-smokers.

Pharmacokinetics of olanzapine in Chinese male schizophrenic patients with various smoking behaviors

Tobacco consumption has been recognized as a factor mediating the interindividual variations in olanzapine's pharmacokinetics and pharmacodynamics. The primary objective of this study was to describe the dose effect of smoking on the dose-plasma concentration relationship and the pharmacokinetics of oral olanzapine in male schizophrenic patients using high-performance liquid chromatography coupled with electrochemical detector. Twenty-seven male schizophrenic inpatients were recruited and were stratified into the following groups according to smoking behaviors: non-smokers (n=9), light-smokers (1-4 cigarettes per day; n=9), and heavy-smokers (>or=5 cigarettes per day; n=9). Plasma olanzapine concentrations were determined up to 120 h following a single oral dose of 10 mg olanzapine. The pharmacokinetic parameters were calculated by the non-compartment method using WinNonlin software. Results show that there was a significant correlation among non-smokers (n=9; 0.79; p=0.01) or combined with light-smokers (n=18; 0.62; p<0.01) between peak plasma olanzapine concentrations (Cmax) and their individual dose-corrected by body weight, but this correlation did not appear in heavy-smokers. There were no significant differences between non-smokers and light-smokers except for significant decreased AUC0-->120 by 45.1% in light-smokers. The mean C(max) and the mean area under the plasma concentration-time curve from time zero to 120 h (AUC0-->120) of the heavy-smoking patients was 9.3+/-4.3 ng/ml (65.2% reduction compared to the non-smokers) and 302.4+/-167.8 h ng/ml (67.6% reduction compared to the non-smokers), respectively. In summary, a daily consumption of 5 cigarettes is probably sufficient for induction of olanzapine metabolism. Smoking cessation is recommended for olanzapine therapy to have better prediction for therapeutic dosages particularly in heavy-smokers. Compared to non-smokers, heavy-smokers therefore require a 50-100% increase in olanzapine doses. Therapeutic drug monitoring will need to be considered when schizophrenic patients change their smoking behaviors.

Cigarette smoking and irinotecan treatment: pharmacokinetic interaction and effects on neutropenia

PURPOSE

Several constituents of cigarette smoke are known to interact with drug metabolizing enzymes and potentially affect treatment outcome with substrate drugs. The purpose of this study was to determine the effects of cigarette smoking on the pharmacokinetics and adverse effects of irinotecan.

PATIENTS AND METHODS

A total of 190 patients (49 smokers, 141 nonsmokers) treated with irinotecan (90-minute intravenous administration on a 3-week schedule) were evaluated for pharmacokinetics. Complete toxicity data were available in a subset of 134 patients receiving 350 mg/m2 or 600 mg flat-fixed dose irinotecan.

RESULTS

In smokers, the dose-normalized area under the plasma concentration-time curve of irinotecan was significantly lower (median, 28.7 v 33.9 ng x h/mL/mg; P = .001) compared with nonsmokers. In addition, smokers showed an almost 40% lower exposure to SN-38 (median, 0.54 v 0.87 ng x h/mL/mg; P < .001) and a higher relative extent of glucuronidation of SN-38 into SN-38G (median, 6.6 v 4.5; P = .006). Smokers experienced considerably less hematologic toxicity. In particular, the incidence of grade 3 to 4 neutropenia was 6% in smokers versus 38% in nonsmokers (odds ratio [OR], 0.10; 95% CI, 0.02 to 0.43; P < .001). There was no significant difference in incidence of delayed-onset diarrhea (6% v 15%; OR, 0.34; 95% CI, 0.07 to 1.57; P = .149).

CONCLUSION

This study indicates that smoking significantly lowers both the exposure to irinotecan and treatment-induced neutropenia, indicating a potential risk of treatment failure. Although the underlying mechanism is not entirely clear, modulation of CYP3A and uridine diphosphate glucuronosyltransferase isoform 1A1 may be part of the explanation. The data suggest that additional investigation is warranted to determine whether smokers are at increased risk for treatment failure.

Vitamin A and emphysema

Within the last several years, research scientists and clinicians have been intrigued with the potential use of an active form of vitamin A, retinoic acid (RA), for the treatment and prevention of emphysema. The interest in this area can be largely attributed to the work of Massaro and Massaro (1996, 1997, 2000) in which they presented evidence that RA partially protects against and to some degree restores elastase-induced emphysema in rats. The mechanism for this protective effect of RA is in part related to elastin metabolism. RA also inhibits inflammation, an upstream event that may lead to the development of emphysema. Although there is evidence of this protective effect in young rats and a mechanistic explanation, more studies are needed in humans in order to establish a role for vitamin A in protecting against emphysema. Too many unanswered questions remain to definitively state that vitamin A protects against this disease in humans. Nevertheless, the potential for this novel approach in prevention and treatment of emphysema is an exciting area of research.

Increased CYP1A1 expression in human exfoliated urothelial cells of cigarette smokers compared to non-smokers

Polycyclic aromatic hydrocarbons, arylamines and nitrosamines, constituents of cigarette smoke, are known inducers of bladder cancer. The biochemical response of the target tissue, the bladder urothelium, following inhalation of cigarette smoke has not been studied so far. We used exfoliated transitional urothelial cells from human urine samples to analyze effects of smoking on induction of the cytochrome P450 enzyme CYP1A1. Samples of 40 subjects, including male and female smokers and non-smokers, were examined. A prerequisite for the immunofluorescence microscopic analysis of the cells was the enrichment of the urothelial cell population. This was achieved by a new method which is based on magnetic cell sorting exploiting specific binding of immobilized Griffonia simplicifolia lectin to the surface of urothelial cells. Immunostaining of the final cell preparation with a monoclonal antibody to CYP1A1 showed that about 6% of the urothelial cells of non-smokers stained positive for CYP1A1. However, this fraction of positive cells was more than 44% of the urothelial cells in samples from cigarette smokers. In spite of the individual variation, the difference was statistically significant. There were no gender-related differences in the portion of CYP1A1 expressing urothelial cells of smokers and non-smokers. In essence, we show for the first time that human urothelial cells respond to cigarette smoking by induction of CYP1A1. The approach opens new fields of mechanistic and biomarker research with respect to the pathogenetic processes of cancer development in the human bladder.

Serum bilirubin levels in the U.S. population: gender effect and inverse correlation with colorectal cancer

Bilirubin, the primary end product of heme catabolism, is a key marker of liver and hematological disorders, and important cytoprotective properties have been ascribed to this bile pigment. The Third National Health and Nutrition Examination Survey, a comprehensive assessment of health and nutrition in the United States, was analyzed to determine the demographics and correlates of serum bilirubin levels in the general population. Men and women aged 17 and older were included in the weighted analysis, representing a total of 176,748,462 subjects. The mean serum total bilirubin in the adult population is 0.62 +/- 0.003 mg/dL (SEM), with a 97.5% cut-off of 1.4 mg/dL. Serum bilirubin levels are significantly higher in men (0.72 +/- 0.004) than in women (0.52 +/- 0.003 mg/dL) and are lower in non-Hispanic blacks (0.55 +/- 0.005 mg/dL) compared with non-Hispanic whites (0.63 +/- 0.004 mg/dL) and Mexican Americans (0.61 +/- 0.005 mg/dL). Bilirubin concentrations are unrelated to body weight but are reduced in active smokers. Individuals with a history of nondermatological malignancy exhibit significantly lower serum bilirubin concentrations compared with those who do not have a history of nondermatological cancer. In particular, each 1-mg/dL increase in serum bilirubin is associated with a markedly decreased prevalence of colorectal cancer (OR = 0.257; 95% CI 0.254-0.260). In conclusion, serum bilirubin levels vary significantly with gender, race, and smoking status. The observed inverse correlation between serum bilirubin concentrations and a history of nondermatological malignancy, particularly colorectal cancer, warrants further investigation of a potentially important chemopreventive function of bilirubin.

Identification of the Main Human Cytochrome P450 Enzymes Involved in Safrole 1‘-Hydroxylation

Safrole is a natural plant constituent, found in sassafras oil and certain other essential oils. The carcinogenicity of safrole is mediated through 1'-hydroxysafrole formation, followed by sulfonation to an unstable sulfate that reacts to form DNA adducts. To identify the main cytochrome P450 (P450) involved in human hepatic safrole 1'-hydroxylation (SOH), we determined the SOH activities of human liver microsomes and Escherichia coli membranes expressing bicistronic human P450s. Human liver (n = 18) microsomal SOH activities were in the range of 3.5-16.9 nmol/min/mg protein with a mean value of 8.7 +/- 0.7 nmol/min/mg protein. In human liver (n = 3) microsomes, the mean K(m) and V(max) values of SOH were 5.7 +/- 1.2 mM and 0.14 +/- 0.03 micromol/min/nmol P450, respectively. The mean intrinsic clearance (V(max)/K(m)) was 25.3 +/- 2.3 microL/min/nmol P450. SOH was sensitive to the inhibition by a CYP2C9 inhibitor, sulfaphenazole, and CYP2E1 inhibitors, 4-methylpyrazole and diethyldithiocarbamate. The liver microsomal SOH activity showed significant correlations with tolbutamide hydroxylation (r = 0.569) and chlorzoxazone hydroxylation (r = 0.770) activities, which were the model reactions catalyzed by CYP2C9 and CYP2E1, respectively. Human CYP2C9 and CYP2E1 showed SOH activities at least 2-fold higher than the other P450s. CYP2E1 showed an intrinsic clearance 3-fold greater than CYP2C9. These results demonstrated that CYP2C9 and CYP2E1 were the main P450s involved in human hepatic SOH.

Vitamin A depletion induced by cigarette smoke is associated with the development of emphysema in rats

We showed previously that vitamin A deficiency per se causes emphysema. Benzo(a)pyrene, a constituent in cigarette smoke, induces vitamin A depletion when administered to rats; therefore, we tested the hypothesis that cigarette smoke induces vitamin A depletion, which is associated with the development of emphysema. Male weanling rats were fed a purified AIN-93G diet and divided into two groups. The experimental group was exposed to cigarette smoke from 20 nonfiltered commercial cigarettes/d for 5 d/wk, whereas the control group was exposed to air. After 6 wk, tissues were collected for histological and biochemical analyses. Retinol levels were measured in serum, lung and liver. The trachea, lung and liver were examined for histological changes. Vitamin A levels decreased significantly in serum, lung and liver of smoke-treated rats. Histological examination revealed the presence of interstitial pneumonitis along with severe emphysema. There was a significant inverse relationship between vitamin A concentration in the lung and the severity of emphysema (r = -0.69 and P < 0.03). Detachment or hyperplasia (and metaplasia) of the tracheal epithelium and liver vacuole formation also were evident in the smoke-treated rats. The results of this research indicate that exposure to cigarette smoke induces vitamin A depletion in rats, which is associated with the development of emphysema.

Lung cancer risk in workers exposed to poly(vinyl chloride) dust: a nested case-referent study

BACKGROUND

There have been few investigations of an association between poly(vinyl chloride) (PVC) dust exposure and an increase in lung cancer incidence, and their conclusions have been inconsistent.

AIMS

To determine whether PVC and/or vinyl chloride monomer (VCM) is the associated risk factor(s), by means of a nested case-referent study, in order to estimate lung cancer risk, avoiding selection, information, or confounding biases.

METHODS

Thirty eight cases of histologically verified lung cancer and 224 control subjects without a history of cancer were selected from an Italian cohort of 1658 vinyl chloride workers. Information sources included clinical records (diagnosis, smoking habits) and plant records (occupational history). The risk of lung cancer was estimated by odds ratios (OR) with 95% confidence intervals (CI), calculated using logistic regression models.

RESULTS

In PVC baggers exposed to high levels of respirable PVC particles in the workplace, the lung cancer OR increases by 20% for each extra year of work (OR = 1.2003; 95% CI 1.0772 to 1.3469; p = 0.0010), when the influence of age and smoking habits is controlled. No relation was found between lung cancer and cumulative VCM exposure.

CONCLUSION

This nested case-control study showed, in the VCM/PVC industry, an increased risk of lung cancer associated with exposure to PVC dust; previous cohort studies failed to recognise such excess, probably because they used VCM exposure as the risk indicator.

Exposing ferrets to cigarette smoke and a pharmacological dose of beta-carotene supplementation enhance in vitro retinoic acid catabolism in lungs via induction of cytochrome P450 enzymes

In our previous studies, we found lower levels of retinoic acid (RA) in the lungs of ferrets exposed to cigarette smoke and/or a pharmacological dose of beta-carotene. To determine whether this is involved in excessive catabolism of RA via cytochrome P450 (CYP) induction, we carried out in vitro incubations of RA with the lung microsomal fractions of ferrets with or without CYP inhibitors and antibodies against CYP. The polar metabolites (4-oxo-RA and 18-hydroxy-RA) of RA metabolism after the incubation were analyzed by HPLC. Expressions of CYP (1A1, 1A2, 2E1 and 3A1) were examined using Western blot analysis. Incubation of various concentrations of RA with the lung microsomal fraction from ferrets exposed to cigarette smoke, a pharmacological dose of beta-carotene or their combination dose-dependently increased the levels of 4-oxo-RA and 18-hydroxy-RA compared with that of the control ferrets. At all RA concentrations, this increase was the greatest in lung tissue from the combined treatment group. Furthermore, this enhanced RA catabolism was substantially (approximately 80%) inhibited by nonspecific CYP inhibitors (disulfiram and liarozole), but was partially (approximately 50%) inhibited by resveratrol (CYP1A1 inhibitor), alpha-naphthoflavone (CYP1A2 inhibitor) and antibodies against CYP1A1 and CYP1A2. Cigarette smoke exposure and/or pharmacological doses of beta-carotene increased levels of CYP1A1 and 1A2 by three- to sixfold but not levels of 2E1 and 3A1 in ferret lung tissue. These findings suggest that low levels of RA in the lung of ferrets exposed to cigarette smoke and/or pharmacological doses of beta-carotene may be caused by the enhanced RA catabolism via induction of CYP, CYP1A1 and CYP1A2 in particular, which provides a possible explanation for enhanced lung carcinogenesis seen with pharmacological doses of beta-carotene supplementation in cigarette smokers.

Enhancement by cigarette smoke exposure of 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline-induced rat hepatocarcinogenesis in close association with elevation of hepatic CYP1A2

The modifying effects of cigarette smoke (CS) exposure on a heterocyclic amine (HCA) 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx)-induced carcinogenesis were investigated in male F344 rats. Groups 1 and 2 were fed MeIQx at a dose of 300 ppm, and simultaneously received CS and sham smoke (SS) for 16 weeks, respectively. Groups 3 - 5 were given the MeIQx diet for 4 weeks, and simultaneously exposed to CS for 4 weeks (group 3), exposed to CS for 12 weeks after the MeIQx treatment (group 4) or received SS for 16 weeks (group 5). Groups 6 and 7 were fed basal diet and respectively received CS and SS for 16 weeks. In terms of the mean number or area, the development of glutathione S-transferase placental form-positive (GST-P(+)) liver cell foci was significantly (P < 0.01) greater in group 1 than in group 2. The mean number of colonic aberrant crypt foci (ACFs) per animal was increased by continuous CS exposure regardless of MeIQx feeding, the differences between groups 4 and 5 (P < 0.05), and between groups 6 and 7 (P < 0.05) being significant. Immunoblot analysis confirmed that the hepatic CYP1A2 level in group 6 was remarkably increased as compared to that in group 7. In addition, liver S9 from rats in group 6 consistently increased the mutagenic activities of six HCAs including MeIQx as compared to those in group 7. Thus, our results clearly indicate that CS enhances hepatocarcinogenesis when given in the initiation phase via increasing intensity of metabolic activation for MeIQx and possibly colon carcinogenesis when given in the post-initiation phase in rats induced by MeIQx.

Effects of cigarette smoke with different tar contents on hepatic and pulmonary xenobiotic metabolizing enzymes in rats

The effects of smoke from cigarettes with two different tar contents (32 mg/cigarette, high tar, and 15 mg/cigarette, low tar) on hepatic and pulmonary monooxygenase (MO) activities (aniline 4-hydroxylase [AH]; aminopyrine N-demethylase [AMND]; 7-ethoxyresorufin O-deethylase [EROD]; p-nitroanisole O-demethylase [p-NAOD]), lipid peroxidation (LP) and reduced glutathione (GSH) levels and glutathione S-transferase (GST) activities toward several substrates (1-chloro-2,4-dinitrobenzene [CDNBI; 1,2-dichloro-4-nitrobenzene [DCNB]; ethacrynic acid [EAA]; 1,2-epoxy-3-(p-nitrophenoxy)-propane [ENPP]) were determined in adult male rats. Adult male rats were exposed to smoke of high- or low-tar cigarettes five times a day, with 1-hour intervals, for 3 days in a chamber where smoke and fresh air lead alternatively and were killed 16 hours after the last treatment. Smoke of both high- and low-tar cigarettes (SHTCC and SLTCC) significantly increased hepatic and pulmonary EROD and p-NAOD activities compared to controls. However, the increase noted by SHTCC on pulmonary EROD activity was higher than that of SLTCC. Hepatic AMND and pulmonary AH activities were significantly increased only by SHTCC. LP level was significantly decreased and increased by SHTCC in liver and lung, respectively, whereas it remained unaltered by SLTCC. Only SHTCC significantly increased GSH level in liver. In the lungs, both SHTCC and SLTCC significantly increased GSH level to the same extent. Hepatic GST activity toward EAA was significantly increased by SHTCC but was significantly decreased by SLTCC. ENPP GST activity was significantly decreased by SHTCC and SLTCC in the livers. In the lungs, all the GST activities examined were significantly depressed by SHTCC whereas only GST activity toward DCNB was reduced significantly by SLTCC. These results reveal that the hepatic and pulmonary MOs and GSTs are differentially influenced by SHTCC and SLTCC in rats.

Serum bilirubin concentration in a Belgian population: the association with smoking status and type of cigarettes

BACKGROUND

The endogenous antioxidant serum bilirubin may scavenge free radical species from cigarette smoke. Smokers are expected to have lower serum bilirubin levels than never smokers, but this has never been evaluated in a random population sample of women and men. In addition, in vitro studies indicate that filter cigarette smoke might enhance bilirubin oxidation more than non-filter cigarette smoke.

METHODS

In this paper, data were analysed from the Belgian Interuniversity Research on Nutrition and Health (BIRNH) study. We investigated the association of smoking and type of cigarettes with serum bilirubin concentrations in men and women using multiple regression models taking into account differences in baseline and smoking characteristics.

RESULTS

In men, current smokers had lower crude and adjusted serum bilirubin concentrations compared with never smokers (P = 0.0001). For women, the association between smoking and serum bilirubin concentrations adjusted for age was in the same direction as for men, but did not reach statistical significance. Male former smokers had serum bilirubin concentrations in between those of current smokers and never smokers, while female former smokers had even higher (+ 0.50 micromol/l) serum bilirubin concentrations than never smokers. Male subjects smoking filter cigarettes showed a higher serum bilirubin concentration than those smoking cigarettes without a filter (adjusted difference: 0.49 micromol/l; P = 0.03). The duration of smoking was inversely and significantly related to serum bilirubin concentrations (P = 0.0003).

CONCLUSION

Smoking may lower serum bilirubin concentrations in men, especially in those smoking non-filter cigarettes. The duration of smoking is a more important determinant for serum bilirubin concentrations than the number of cigarettes smoked per day, which may indicate the cumulative negative effects of smoking on the endogenous antioxidant system. Results for females pointed in the same direction, but were less clear, possibly due to low numbers of smoking women, who were largely young and smoked mainly filter cigarettes for a shorter period of time.

The effect of retinol on hepatic and renal drug-metabolising enzymes

Retinol pretreatment (75 mg/kg/day, 4 days) potentiated paracetamol-induced hepatotoxicity in BALB/c mice (alanine aminotransferase (ALT) activity; 2510+/-602 vs 1155+/-282 IU/l; retinol+paracetamol vs corn oil+paracetamol, respectively, P<0.05); however, this potentiation did not occur in the kidney, indicating an organ-specific response. Retinol treatment alone was not toxic in either organ, as indicated by ALT activity, blood urea nitrogen and creatinine. The potentiation effect could be mediated by retinol's induction of CYP450 isoforms relevant to paracetamol metabolism or through depletion of glutathione. Therefore, these parameters were investigated in both organs. Following retinol treatment, renal CYP2E1 and hepatic CYP1A2 and CYP2E1 catalytic activities and polypeptide levels were unchanged. However, retinol significantly decreased both the catalytic activity (0.23+/-0.03 vs 0.53+/-0.06 nmol/mg/min; retinol vs untreated, respectively, P<0.05) and polypeptide levels (58+/-0.6% of control) of hepatic CYP3A. Inhibition of renal CYP3A did not occur as catalytic activity and polypeptide levels were unchanged from control. Following retinol treatment, total reduced glutathione levels, in both organs, were not significantly different from control. Therefore, the potentiation of paracetamol-induced hepatotoxicity is independent of CYP450 and glutathione.

Factors affecting serum haloperidol level assessed by longitudinal therapeutic monitoring

1. Since the development of a kit for the assay of haloperidol by enzyme immunoassay, therapeutic monitoring of haloperidol has been utilised in Japan for several years. By retrospectively analysing the accumulated data, this study was carried out to investigate the factors affecting haloperidol level. Especially, the effects of enzyme-inducing comedications were analysed in relation to serum gamma-glutamyltransferase (GGT) level, which has been measured simultaneously with haloperidol. Serum haloperidol level measurements were obtained from medical records of inpatients on multiple medications (n = 102). For each subject, average haloperidol level was computed during the same prescription and doses. The effects of age, sex, smoking status, and the coadministration of carbamazepine and barbiturates (including phenobarbital, amobarbital and pentobarbital) were analysed using correlation, between-group comparison and multiple regression analysis. Separately, the effect of comedications on haloperidol and GGT levels were analysed individually in a small number of patients (n = 5) who had received those comedications intermittently. Significant lowering of serum haloperidol level by the coadministration of carbamazepine and/or barbiturates was observed. The coadministration was also correlated with the elevated GGT level in between-group comparison. In the separate analysis, the change in haloperidol level was correlated with the change in GGT level in some individuals but not in others. None of the other clinical factors investigated in the study showed significant effect on haloperidol level. This study suggests that the lowering of haloperidol level and the elevation of GGT level may often occur coincidentally by the coadministration of enzyme-inducing drugs. However, whether there is a causal relationship between these phenomena and whether elevated serum GGT level could serve as a clinically useful marker need to be clarified by further basic pharmacological research.

Prolonged exposure to cigarette smoke blocks the neurotoxicity induced by kainic acid in rats

We examined the effects of cigarette smoke (CS) on three parameters associated with kainic acid (KA)-induced neurotoxicity: seizure activity, cell loss in the hippocampus, and increased Fos-related antigen (FRA) expression. Animals were exposed to the main stream of CS from 15 Kentucky 2R1F research cigarettes containing 28.6 mg tar and 1.74 mg nicotine per cigarette, for 10 min a day, 6 days per week, for 4 weeks, using an automatic smoking machine. KA administration (10 mg/kg, i.p.) produced robust behavioral convulsions lasting 4-5 h. Pre-exposure to CS significantly reduced the seizures, mortality, and severe loss of cells in regions CA1 and CA3 of the hippocampus after KA administration. Consistently, pre-exposure to CS significantly attenuated the KA-induced increased FRA immunoreactivity in the hippocampus. In contrast, pretreatment with central nicotinic antagonist, mecamylamine (2 or 10 mg/kg, i.p.) blocked the neuroprotective effects mediated by CS in a dose-dependent manner. These results indicate that CS exposure provides neuroprotection against the KA insult via nicotinic receptor activation.

Morphine regulation of a novel uridine diphosphate glucuronosyl-transferase in guinea pig pups following in utero exposure

The uridine diphosphate glucuronosyltransferases (UGTs) catalyze conjugation reactions between various substrates and glucuronic acid, UDPGA (uridine diphosphate glucuronic acid), within the endoplasmic reticulum. Conjugation with UDPGA (glucuronidation) is an important pathway in the elimination, detoxification, and activation of compounds including steroid hormones, xenobiotics, and quaternary ammonium substrates. The guinea pig, which has a placental structure and a glucuronidation profile for morphine that are similar to the human, serves as a good small animal model to study the ontogeny of UGTs and the effect of in utero exposure to morphine on UGTs. We examined type 2 UGTs expressed in the guinea pig using amplification and cloning of partial cDNAs from liver RNA. Sequence analysis revealed a novel UGT2 (subsequently named UGT2A3),(2) that has a 64% amino acid sequence similarity to a known UGT2.(3) Full-length cDNAs were isolated from a guinea pig liver cDNA library. Tissue distribution of UGT2A3 using Northern blot analysis showed expression of three distinct size UGT2A3 mRNAs with unique expression in liver and small intestine. UGT2A3 mRNA is expressed at high levels in liver and lower levels in kidney and small intestine. In utero exposure to chronic intermittent morphine resulted in the up regulation of mRNA in 7-day-old female pups' liver and kidney as determined by quantitative RT-PCR analysis. The conjugation profile for UGT2A3 using stable expression in CHO cells and thin-layer chromatography demonstrated active conjugation of phenolic substrates. Regulation of UGTs by in utero morphine exposure may play an important role in fetal development.