Slower metabolism and reduced intake of nicotine from cigarette smoking in Chinese-Americans

Smoking topography in Korean American and white men: preliminary findings

This is the first study of Korean Americans' smoking behavior using a topography device. Korean American men smoke at higher rates than the general U.S.

POPULATION

Korean American and White men were compared based on standard tobacco assessment and smoking topography measures. They smoked their preferred brand of cigarettes ad libitum with a portable smoking topography device for 24 h. Compared to White men (N = 26), Korean American men (N = 27) were more likely to smoke low nicotine-yield cigarettes (p < 0.001) and have lower Fagerstrom nicotine dependence scores (p = 0.04). Koreans smoked fewer cigarettes with the device (p = 0.01) than Whites. Controlling for the number of cigarettes smoked, Koreans smoked with higher average puff flows (p = 0.05), greater peak puff flows (p = 0.02), and shorter interpuff intervals (p < 0.001) than Whites. Puff counts, puff volumes, and puff durations did not differ between the two groups. This study offers preliminary insight into unique smoking patterns among Korean American men who are likely to smoke low nicotine-yield cigarettes. We found that Korean American men compensated their lower number and low nicotine-yield cigarettes by smoking with greater puff flows and shorter interpuff intervals than White men, which may suggest exposures to similar amounts of nicotine and harmful tobacco toxins by both groups. Clinicians will need to consider in identifying and treating smokers in a mutually aggressive manner, irrespective of cigarette type and number of cigarette smoked per day.

Biomarkers of tobacco smoke exposure in racial/ethnic groups at high risk for lung cancer

OBJECTIVES

We examined biomarkers of tobacco smoke exposure among Native Hawaiians, Filipinos, and Whites, groups that have different lung cancer risk.

METHODS

We collected survey data and height, weight, saliva, and carbon monoxide (CO) levels from a sample of daily smokers aged 18-35 (n = 179). Mean measures of nicotine, cotinine, cotinine/cigarettes per day ratio, trans 3' hydroxycotinine, the nicotine metabolite ratio (NMR), and expired CO were compared among racial/ethnic groups.

RESULTS

The geometric means for cotinine, the cotinine/cigarettes per day ratio, and CO did not significantly differ among racial/ethnic groups in the adjusted models. After adjusting for gender, body mass index, menthol smoking, Hispanic ethnicity, and number of cigarettes smoked per day, the NMR was significantly higher among Whites than among Native Hawaiians and Filipinos (NMR = 0.33, 0.20, 0.19, P ≤ .001). The NMR increased with increasing White parental ancestry. The NMR was not significantly correlated with social-environmental stressors.

CONCLUSIONS

Racial/ethnic groups with higher rates of lung cancer had slower nicotine metabolism than Whites. The complex relationship between lung cancer risk and nicotine metabolism among racial/ethnic groups needs further clarification.

N-acetyltransferase 1 polymorphism increases cotinine levels in Caucasian children exposed to secondhand smoke: the CCAAPS birth cohort

Cotinine is a proxy for secondhand smoke (SHS) exposure. Genetic variation along nicotine and cotinine metabolic pathways may alter the internal cotinine dose, leading to misinterpretations of exposure-health outcome associations. Caucasian children with available SHS exposure and hair cotinine data were genotyped for metabolism-related genes. SHS-exposed children had 2.4-fold higher hair cotinine (0.14±0.22 ng mg(-1)) than unexposed children (0.06±0.05 ng mg(-1), P<0.001). SHS-exposed children carrying the NAT1 minor allele had twofold higher hair cotinine (0.18 ng mg(-1) for heterozygotes and 0.17 ng mg(-1) for homozygotes) compared with major allele homozygotes (0.09 ng mg(-1), P=0.0009), even after adjustment for SHS dose. These findings support that NAT1 has a role in the metabolic pathway of nicotine/cotinine and/or their metabolites. The increased cotinine levels observed for those carrying the minor allele may lead to SHS exposure misclassification in studies utilizing cotinine as a biomarker. Additional studies are required to identify functional single-nucleotide polymorphism(s) (SNP(s)) in NAT1 and elucidate the biological consequences of the mutation(s).

Association of CYP2A6 gene polymorphisms with cigarette consumption: a meta-analysis

AIMS

A meta-analysis was performed to assess the association of hepatic cytochrome P450 2A6 (CYP2A6) gene polymorphisms with cigarette consumption.

METHODS

A comprehensive search was conducted to identify the studies of the above-mentioned association. The fixed effect model (FEM) or random effect model (REM) was selected based on the homogeneity test among studies. Heterogeneity among studies was evaluated using the I(2). Meta-regression and the "leave one out" sensitive analysis were utilized to explore potential sources of heterogeneity. Publication bias was estimated by Harbord test. The effect of CYP2A6 gene polymorphisms on cigarette consumption was presented as standardized mean difference (SMD) with 95% confidence intervals (CI).

RESULTS

After excluding one article that was the key contributor to between-study heterogeneity, there was a significant difference of cigarettes per day in groups of normal vs. reduced metabolizers of CYP2A6 gene (FEM: SMD = 0.134, 95%CI: 0.049-0.219). There was also a significant difference of age of smoking initiation between normal and intermediate metabolizers of CYP2A6 gene (FEM: SMD = 0.216, 95%CI: 0.056-0.377). No significant difference of tobacco dependence between normal and reduced metabolizers of CYP2A6 gene was found (FEM: SMD = 0.185, 95%CI = -0.001 to 0.371).

CONCLUSION

This meta-analysis suggests that CYP2A6 gene polymorphism is associated with daily cigarette consumption. Individuals with intermediate nicotine metabolism might also initiate smoking later than normal metabolism.

Serum cotinine and urinary 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanonol levels among non-Hispanic Asian American smokers and nonsmokers as compared to other race/ethnicities: data from NHANES 2011-2012

The objective of this study was to evaluate serum cotinine and total urinary 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanonol (NNAL) levels from a nationally representative sample of non-Hispanic Asian Americans as compared with other racial/ethnic groups. Data from the latest National Health and Nutrition Examination Survey for the years 2011-2012 were used for this purpose. The total sample size used was 4580. Regression models were fitted to estimate serum cotinine and urinary NNAL levels for smokers and nonsmokers aged 20 years and older adjusted for other factors that affect these levels. For nonsmokers, exposure to second hand smoke at home was associated with about 30 times higher serum cotinine levels when compared to those without such exposure (0.717 ng mL(-1) vs. 0.024 ng mL(-1), p<0.01). NNAL levels among nonsmokers with second hand smoke exposure at home were about twenty times what they were in those without such exposure (9 pg mL(-1) vs. 109 pg mL(-1), p<0.01). As compared to other racial/ethnic groups, the lowest adjusted serum cotinine levels occurred in non-Hispanic Asian smokers (92.6 ng mL(-1)) and Hispanics (84.5 ng mL(-1)) as compared to non-Hispanic whites (143.8 ng mL(-1)) and non-Hispanic blacks (158.4 ng mL(-1)). Urinary NNAL levels for smokers were in the order: non-Hispanic Asian (0.121 ng mL(-1))<non-Hispanic blacks (0.139 ng mL(-1))<Hispanics (0.201 ng mL(-1))<non-Hispanic whites (0.234 ng mL(-1)). Compared to non-Hispanic whites, non-Hispanic blacks had substantially higher levels of serum cotinine but substantially lower levels of urinary NNAL irrespective of smoking status thus pointing towards differences in elimination kinetics of nicotine/cotinine and NNAL.

Validation of a LC-MS/MS method for quantifying urinary nicotine, six nicotine metabolites and the minor tobacco alkaloids--anatabine and anabasine--in smokers' urine

Tobacco use is a major contributor to premature morbidity and mortality. The measurement of nicotine and its metabolites in urine is a valuable tool for evaluating nicotine exposure and for nicotine metabolic profiling--i.e., metabolite ratios. In addition, the minor tobacco alkaloids--anabasine and anatabine--can be useful for monitoring compliance in smoking cessation programs that use nicotine replacement therapy. Because of an increasing demand for the measurement of urinary nicotine metabolites, we developed a rapid, low-cost method that uses isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS) for simultaneously quantifying nicotine, six nicotine metabolites, and two minor tobacco alkaloids in smokers' urine. This method enzymatically hydrolyzes conjugated nicotine (primarily glucuronides) and its metabolites. We then use acetone pretreatment to precipitate matrix components (endogenous proteins, salts, phospholipids, and exogenous enzyme) that may interfere with LC-MS/MS analysis. Subsequently, analytes (nicotine, cotinine, hydroxycotinine, norcotinine, nornicotine, cotinine N-oxide, nicotine 1'-N-oxide, anatabine, and anabasine) are chromatographically resolved within a cycle time of 13.5 minutes. The optimized assay produces linear responses across the analyte concentrations typically found in urine collected from daily smokers. Because matrix ion suppression may influence accuracy, we include a discussion of conventions employed in this procedure to minimize matrix interferences. Simplicity, low cost, low maintenance combined with high mean metabolite recovery (76-99%), specificity, accuracy (0-10% bias) and reproducibility (2-9% C.V.) make this method ideal for large high through-put studies.

Cigarette smoking and gestational diabetes mellitus in Hispanic woman

AIMS

Hispanic women are at increased risk of gestational diabetes mellitus (GDM) as compared to non-Hispanic white women. While smoking has been associated with increased risk of type 2 diabetes, studies of smoking and GDM are sparse and conflicting. Therefore, we evaluated the relationship between cigarette smoking and GDM in Hispanic women.

METHODS

We conducted a pooled analysis of two Hispanic datasets based in Massachusetts: the UMass Medical Health Care dataset and the Proyecto Buena Salud dataset. A total of 3029 Hispanic prenatal care patients with singleton gestations were included. Cigarette smoking prior to and during pregnancy was collected via self-report. Diagnosis of GDM was abstracted from medical records and confirmed by study obstetricians.

RESULTS

One-fifth of participants (20.4%) reported smoking prior to pregnancy, and 11.0% reported smoking in pregnancy. A total of 143 women (4.7%) were diagnosed with GDM. We did not observe an association between pre-pregnancy cigarette smoking and odds of GDM (multivariable OR=0.77, 95% CI 0.47, 1.25). In contrast, smoking during pregnancy was associated with a 54% reduction in odds of GDM (OR=0.46, 95% CI 0.22, 0.95). However, this association was no longer statistically significant after adjustment for age, parity, and study site (OR=0.47, 95% CI 0.23, 1.00).

CONCLUSIONS

In this population of Hispanic pregnant women, we did not observe statistically significant associations between pre-pregnancy smoking and odds of GDM. A reduction in odds of GDM among those who smoked during pregnancy was no longer apparent after adjustment for important diabetes risk factors.

A comparison of nicotine biomarkers and smoking patterns in daily and nondaily smokers

BACKGROUND

Nondaily or intermittent smokers (ITS) are increasingly common, but how much nicotine, if any, ITS take in and how quickly they metabolize it has not yet been studied.

METHODS

We compared carbon monoxide (CO), urinary cotinine, and nicotine metabolism [nicotine metabolite ratio (NMR): 3-hydroxycotinine:cotinine] in 224 ITS and 222 daily smokers (DS). Effects of gender and ethnicity were examined.

RESULTS

DS had higher cotinine concentrations than ITS (1,396 ± 69 vs. 478 ± 44 ng/mL), attributable to higher cigarettes per day (CPD). In both groups, cotinine rose more slowly as CPD increased. There were no differences in cotinine between White (WH) and African American (AA) DS; among ITS, AA cotinine was over twice that of WH. Among DS, CO was significantly higher among WH than AA smokers, but significantly lower among WH ITS than AA ITS. Although AA ITS smoked more than WH ITS (CPD: 4.13 ± 0.55 vs. 3.31 ± 0.41), this did not account for the observed cotinine nor CO differences. There were no differences in NMR by group or race, nor any gender effects.

CONCLUSIONS

At comparable CPD, DS' and ITS' intake of nicotine per cigarette was similar, as were their rates of nicotine metabolism. Among ITS, AA smokers smoke more and take in more nicotine per cigarette than WH ITS, consistent with the view of ITS as a heterogeneous group.

IMPACT

Differences in nicotine intake per cigarette and metabolism likely cannot account for differences in DS and ITS smoking. Future studies should explore ethnic differences in ITS smoking.

Effects of methoxsalen, a CYP2A5/6 inhibitor, on nicotine dependence behaviors in mice

Metabolism of nicotine to inactive cotinine by hepatic enzyme CYP2A6 is the principal pathway by which active nicotine is removed from circulation. We therefore hypothesized that inhibition of mouse CYP2A5, the ortolog of human CYP2A6, by methoxsalen (8-methoxypsoralen) alter dependence-related behaviors of nicotine in the mouse. Conditioned place preference (CPP) test was used to assess the appetitive reward-like properties and precipitated nicotine withdrawal to assess physical (somatic and hyperalgesia) and affective (anxiety-related behaviors) measures. The nicotine plasma levels were also measured with or without methoxsalen pretreatment. Methoxsalen (15 and 30 mg/kg, intraperitoneally) pretreatment enhanced nicotine-induced preference in mice (p<0.05). However, there was a lack of enhancement of nicotine in the CPP test after the highest dose of the CYP-2A5 inhibitor. Similarly to the CPP results, repeated administration of methoxsalen increased the intensity of mecamylamine-precipitated withdrawal signs. The potentiation of nicotine preference and withdrawal intensity by methoxsalen was accompanied by significant increase in nicotine plasma levels in mice (p<0.05). Finally, methoxsalen enhanced the ability of a very low dose of nicotine (0.05 mg/kg) to reverse withdrawal signs in mice undergoing spontaneous withdrawal after chronic nicotine infusion (p<0.05). In conclusion, inhibition of nicotine metabolism by methoxsalen alters the behavioral effects of nicotine in the mouse. Combining CYP2A6 inhibitors with low dose nicotine replacement therapies may have a beneficial role in smoking cessation because it will decrease the drug elimination rate and maintain plasma and brain nicotine levels.

Increases in light and intermittent smoking among Asian Americans and non-Hispanic Whites

INTRODUCTION

Asian Americans are the fastest growing immigrant group in the United States and are more likely to be light and intermittent smokers (LITS) compared with non-Hispanic Whites (NHWs). LITS experience adverse health effects related to smoking. Previous research has aggregated Asian American ethnic groups, masking important differences between groups. We sought to compare LITS rates among Asian American subgroups before and after the 1998 Master Settlement Agreement (MSA) with NHWs in California utilizing data from the California Tobacco Surveys (CTS).

METHODS

We combined 1990, 1992, and 1996 CTS (pre-MSA) and the 1999, 2002, 2005, and 2008 CTS (post-MSA) to examine changes in LITS (<10 cigarettes/day or not smoking daily). Chinese, Filipino, Japanese, and Korean ethnic groups were compared with NHWs.

RESULTS

Pre-MSA logistic regression models adjusted for age, gender, education level, language spoken at home, and use of other tobacco products found that Chinese (odds ratio [OR] = 3.38, 95% confidence interval [CI] = 2.19, 5.21), Filipinos (OR = 3.55, 95% CI = 2.73, 4.63), Japanese (OR = 1.99, 95% CI = 1.22, 3.27), and Koreans (OR = 3.22, 95% CI = 2.06, 5.03) were significantly more likely to be LITS compared with NHWs. Post-MSA, all Asian American subgroups experienced an increase in LITS (11.7%-37.8%); however, only Chinese (OR = 2.19, 95% CI = 1.16, 4.13) and Filipinos (OR = 3.33, 95% CI = 2.26, 4.91) remained significantly more likely to be LITS compared with NHWs.

CONCLUSIONS

Our results highlight the need for tobacco control efforts that address the growing group of LITS among Asian Americans and NHWs.

Genetic and pharmacokinetic determinants of response to transdermal nicotine in white, black, and Asian nonsmokers

The aim of the study was to examine genetic, pharmacokinetic and demographic factors that influence sensitivity to nicotine in never smokers. Sixty never smokers, balanced for gender and race (Caucasian, Blacks and Asian), wore 7 mg nicotine skin patches for up to 8 hours. Serial plasma nicotine concentrations and subjective and cardiovascular effects were measured, and genetic variation in the CYP2A6 gene, the primary enzyme responsible for nicotine metabolism, was assessed. Nicotine toxicity requiring patch removal developed in 9 subjects and was strongly associated with rate of rise and peak concentrations of plasma nicotine. Toxicity, subjective and cardiovascular effects of nicotine were associated with the presence of reduced function CYP2A6 alleles, presumably reflecting slow nicotine metabolic inactivation. This study has implications for understanding individual differences in responses to nicotine medications, particularly when the latter are used for treating medical conditions in non-smokers, and possibly in vulnerability to developing nicotine dependence.

Variation in trans-3'-hydroxycotinine glucuronidation does not alter the nicotine metabolite ratio or nicotine intake

BACKGROUND

CYP2A6 metabolizes nicotine to its primary metabolite cotinine and also mediates the metabolism of cotinine to trans-3'-hydroxycotinine (3HC). The ratio of 3HC to cotinine (the "nicotine metabolite ratio", NMR) is an in vivo marker for the rate of CYP2A6 mediated nicotine metabolism, and total nicotine clearance, and has been associated with differences in numerous smoking behaviors. The clearance of 3HC, which affects the NMR, occurs via renal excretion and metabolism by UGT2B17, and possibly UGT2B10, to 3HC-glucuronide. We investigated whether slower 3HC glucuronidation alters NMR, altering its ability to predict CYP2A6 activity and reducing its clinical utility.

METHODS

Plasma NMR, three urinary NMRs, three urinary 3HC glucuronidation phenotypes and total nicotine equivalents were examined in 540 African American smokers. The UGT2B17 gene deletion and UGT2B10*2 were genotyped.

RESULTS

The UGT2B17 gene deletion, but not UGT2B10*2 genotype, was associated with slower 3HC glucuronidation (indicated by three 3HC-glucuronidation phenotypes), indicating its role in this glucuronidation pathway. However, neither lower rates of 3HC glucuronidation, nor the presence of a UGT2B17 and UGT2B10 reduced function allele, altered plasma or urinary NMRs or levels of smoking.

CONCLUSIONS

Variation in 3HC glucuronidation activity, including these caused by UGT2B17 gene deletions, did not significantly alter NMR and is therefore unlikely to affect the clinical utility of NMR in smoking behavior and cessation studies. This study demonstrates that NMR is not altered by differences in the rate of 3HC glucuronidation, providing further support that NMR is a reliable indicator of CYP2A6 mediated nicotine metabolism.

Pharmacokinetic and pharmacodynamics studies of nicotine after oral administration in mice: effects of methoxsalen, a CYP2A5/6 inhibitor

INTRODUCTION

The use of novel oral nicotine delivery devices and compositions for human consumption and for animal research studies has been increasing in the last several years.

METHODS

Studies were undertaken to examine whether the systemic administration of methoxsalen, an inhibitor of human CYP2A6 and mouse CYP2A5, would modulate nicotine pharmacokinetics and pharmacological effects (antinociception in the tail-flick, and hot-plate tests, and hypothermia) in male ICR mouse after acute oral nicotine administration.

RESULTS

Administration of intra peritoneal (ip) methoxsalen significantly increased nicotine's Cmax, prolonged the plasma half-life (fourfold decrease) of nicotine, and increased its area under the curve (AUC) compared with ip vehicle treatment. Methoxsalen pretreatment prolonged the duration of nicotine-induced antinociception and hypothermia (15mg/kg, po) for periods up to 6- and 24-hr postnicotine administration, respectively. Additionally, methoxsalen potentiated nicotine-induced antinociception and hypothermia as evidenced by leftward shifts in nicotine's dose-response curve. Furthermore, this prolongation of nicotine's effects after methoxsalen was associated with a parallel prolongation of nicotine plasma levels in mice. These data strongly suggest that variation in the rates of nicotine metabolic inactivation substantially alter pharmacological effects of nicotine given orally.

CONCLUSION

We have shown that the pharmacological effects of inhibiting nicotine's metabolism after oral administration in mice are profound. Our results suggest that inhibiting nicotine metabolism can be used to dramatically enhance nicotine's bioavailability and its resulting pharmacology, which further supports this inhibitory approach for clinical development of an oral nicotine replacement therapy.

Race, gender, and nicotine metabolism in adolescent smokers

INTRODUCTION

Differences in the rate of nicotine metabolism between genders and different races have been hypothesized to contribute to disparities in smoking rate, susceptibility to addiction, and ability to quit smoking. The purpose of this study was to determine the effect of race and gender on the rate of nicotine metabolism as indicated by the nicotine metabolite ratio (NMR) in adolescent smokers.

METHODS

One hundred and fifty-nine adolescent smokers aged 13-17 were given 2mg of deuterium-labeled cotinine (cotinine-d4). The NMR was calculated as the ratio of concentrations of deuterium-labeled 3'-hydroxycotinine (ng/ml) to cotinine-d4 (ng/ml) in saliva and is a validated biomarker of the rate of nicotine metabolism.

RESULTS

The sample was 67.3% female and racially mixed. On average, Whites had the fastest rates of metabolism compared with both Blacks/African Americans (p < .01) and Asians (p = .01). The NMR was similar between males and females (p = .70). Among the 19 girls who reported using estrogen-containing contraceptives, there was no significant difference in NMR compared with the 83 girls who did not use contraceptives (p = .24) or the 10 who used progestin-only contraceptives (p = .45).

CONCLUSIONS

Among adolescent smokers, racial variations in rates of nicotine metabolism were similar to those that have been reported in adult smokers. In contrast to findings in adult smokers, the NMR did not vary significantly by gender or self-reported hormone use.

Level of cigarette consumption and quit behavior in a population of low-intensity smokers--longitudinal results from the International Tobacco Control (ITC) survey in Mexico

BACKGROUND

Mexican smokers are more likely to be non-daily smokers and to consume fewer cigarettes per day than smokers in other countries. Little is known about their quit behaviors.

AIM

The aim of this study is to determine factors associated with having made a quit attempt and being successfully quit at 14-month follow-up in a population-based cohort of adult Mexicans who smoke at different levels of intensity.

DESIGN

A longitudinal analysis of wave-III and wave-IV (2010) Mexican administration of International Tobacco Control Policy Evaluation Project was conducted.

SETTING

This study was conducted in six large urban centers in Mexico

PARTICIPANTS

The participants of this study comprised 1206 adults who were current smokers at wave-III and who were followed to wave-IV.

MEASUREMENTS

We compared three groups of smokers: non-daily smokers-who did not smoke every day in the past 30 days (n=398), daily light smokers who smoked every day at a rate of ≤5 cigarettes per day (n=368) and daily heavy smokers who smoked every day at a rate of >5 cigarettes per day (n=434). Data on smoking behavior, psychosocial characteristics and socio-demographics were collected at baseline and after 14 months.

FINDINGS

In multivariate logistic regression predicting having made a quit attempt at follow-up, significant factors included being a non-daily smoker versus a heavy daily smoker (ORadj=1.83, 95% CI: 1.19-2.83), less perceived addiction (ORadj=1.86, 95% CI: 1.20-2.87), greater worry that cigarettes will damage health (ORadj=2.04, 95% CI: 1.16-3.61) and having made a quit attempt in the past year at baseline (ORadj=1.70, 95% CI: 1.23-2.36). In multivariate logistic regression predicting being successfully quit at one-year follow-up, significant factors included being a non-daily smoker versus a heavy daily smoker (ORadj=2.54, 95% CI: 1.37-4.70) and less perceived addiction (not addicted: ORadj=3.26, 95% CI: 1.73-6.14; not much: ORadj=1.95, 95% CI: 1.05-3.62 versus very much).

CONCLUSIONS

Mexican adult smokers who are non-daily smokers were more likely than daily heavy smokers to have attempted to quit during follow-up and to succeed in their quit attempt. Future research should determine whether tobacco control policies and programs potentiate this tendency and which interventions are needed to help heavier smokers to quit.

Determination of tobacco smoke exposure by plasma cotinine levels in infants and children attending urban public hospital clinics

OBJECTIVE To determine the prevalence of secondhand smoke (SHS) exposure among infants and young children who received preventive care at pediatric preventative care clinics associated with an urban public hospital. Cotinine, a metabolite of nicotine, has been used to study SHS exposure in population-based studies of children 3 years of age or older. DESIGN Retrospective study using a convenience sample. SETTING Urban county pediatric primary care clinics in San Francisco, California. PARTICIPANTS A total of 496 infants and children (mean [SD] age, 2.4 [1.9] years). INTERVENTIONS Discarded plasma samples (which were routinely collected for lead screening) were tested, and medical records were reviewed, for SHS exposure. MAIN OUTCOME MEASURE Secondhand smoke exposure based on cotinine plasma level and history of exposure in the medical record. RESULTS Thirteen percent of parents reported that their child was exposed to SHS, yet biochemical testing detected cotinine in 55% of samples, at a geometric mean (SD) of 0.23 (3.55) ng/mL. There were no significant sex or age differences. African American children had much higher mean cotinine levels than did Latino children (multiplicative factor change in cotinine, 6.01 ng/ml [95% Cl, 4.49-8.05 ng/ml] [correction]. CONCLUSION In a city with a low smoking rate (12%) and public smoking bans, we documented 55% exposure among infants and young children, using a plasma biomarker, compared with 13% exposure reported by parents. Because SHS is associated with significant respiratory diseases and parents underreport exposure, routine biochemical screening should be considered as a tool to identify and reduce SHS exposure.

Nicotine metabolism and addiction among adolescent smokers

AIMS

The purpose of this study was to determine the association between the nicotine metabolic rate and smoking behavior, including addiction, in adolescent smokers.

DESIGN

Baseline data from a prospective study of adolescent smoking behaviors and nicotine metabolism.

SETTING

The setting was an out-patient university hospital in San Francisco.

PARTICIPANTS

Adolescent smokers (n = 164) aged 13-17 years old.

MEASUREMENTS

Participants completed self-report measures of smoking behavior and nicotine dependence (modified Fagerström Tolerance Questionnaire: mFTQ). The nicotine metabolite ratio (NMR), a phenotypic marker of the rate of nicotine metabolism, was calculated using the ratio of concentrations of deuterium-labeled 3'-hydroxycotinine to cotinine-d(4) .

FINDINGS

Participants reported smoking a mean of 2.86 cigarettes per day (CPD) [median = 1.78, standard deviation (SD) = 3.35] for 1.37 years (median = 1.0, SD = 1.36). Results from multivariate analyses accounting for age, race/ethnicity, gender and duration of smoking indicated that slower metabolizers smoked more CPD than faster metabolizers (the NMR was inversely related to CPD; P = 0.02). Slower metabolizers also showed greater dependence on the mFTQ (NMR was negatively associated with the mFTQ; P = 0.02).

CONCLUSIONS

In adolescence, slower clearance of nicotine may be associated with greater levels of addiction, perhaps mediated by a greater number of cigarettes smoked.

A multi-route model of nicotine-cotinine pharmacokinetics, pharmacodynamics and brain nicotinic acetylcholine receptor binding in humans

The pharmacokinetics of nicotine, the pharmacologically active alkaloid in tobacco responsible for addiction, are well characterized in humans. We developed a physiologically based pharmacokinetic/pharmacodynamic model of nicotine pharmacokinetics, brain dosimetry and brain nicotinic acetylcholine receptor (nAChRs) occupancy. A Bayesian framework was applied to optimize model parameters against multiple human data sets. The resulting model was consistent with both calibration and test data sets, but in general underestimated variability. A pharmacodynamic model relating nicotine levels to increases in heart rate as a proxy for the pharmacological effects of nicotine accurately described the nicotine related changes in heart rate and the development and decay of tolerance to nicotine. The PBPK model was utilized to quantitatively capture the combined impact of variation in physiological and metabolic parameters, nicotine availability and smoking compensation on the change in number of cigarettes smoked and toxicant exposure in a population of 10,000 people presented with a reduced toxicant (50%), reduced nicotine (50%) cigarette Across the population, toxicant exposure is reduced in some but not all smokers. Reductions are not in proportion to reductions in toxicant yields, largely due to partial compensation in response to reduced nicotine yields. This framework can be used as a key element of a dosimetry-driven risk assessment strategy for cigarette smoke constituents.

Bioequivalence and rapid absorption of zolmitriptan nasal spray compared with oral tablets in healthy Japanese subjects

BACKGROUND AND OBJECTIVE

Oral zolmitriptan is highly effective in the acute treatment of migraine. However, nausea and vomiting during attacks may limit the usefulness of oral medications. An alternative, nasal spray, formulation has been developed that demonstrates good efficacy, high tolerability and a very fast onset of action. This study assessed the pharmacokinetics and bioavailability of zolmitriptan and its active metabolite 183C91 in healthy Japanese subjects following single-dose (2.5 or 5mg) oral or intranasal administration.

METHODS

This was a single-centre, open-label, randomised, crossover study. Forty-eight subjects each received one oral and one intranasal dose of 2.5 or 5mg zolmitriptan, with a 72-hour washout period between doses. Blood was drawn at various timepoints from 2 minutes to 15 hours post-dose and urine was collected over the course of the study; samples were analysed for zolmitriptan and 183C91, from which pharmacokinetic parameters were calculated.

RESULTS

Zolmitriptan was detected in plasma 2 minutes after intranasal administration in the majority of subjects (~75%) compared with 10 minutes after oral administration. The intranasal : tablet ratio for zolmitriptan area under the concentration-time curve from time zero to infinity was 0.924 (90% CI 0.826, 1.033) and 0.960 (90% CI 0.865, 1.066) for the 2.5 and 5mg doses, respectively. Other pharmacokinetic parameters were similar between the two formulations. While 183C91 appeared in the plasma concurrently to zolmitriptan after oral dosing, its appearance was delayed to approximately 30 minutes after intranasal dosing. Zolmitriptan was safe and well tolerated at both doses.

CONCLUSIONS

The rapid absorption of zolmitriptan nasal spray may explain the faster relief from migraine reported in patients compared with oral zolmitriptan.

Superior methadone treatment outcome in Hmong compared with non-Hmong patients

The Hmong are a distinct ethnic group from Laos. Little is known about how opiate-addicted Hmong respond to methadone maintenance treatment. Therefore, opium-addicted Hmong (exclusive route of administration: smoking) attending an urban methadone maintenance program in Minneapolis, MN, were matched by gender and date of admission with predominately heroin-addicted non-Hmong (predominant route of administration: injection) attending the same program, and both groups were evaluated for 1-year treatment retention, stabilization dose of methadone, and urine drug screen results. Hmong had greater 1-year treatment retention (79.8%) than non-Hmong (63.5%; p < .01). In both groups, methadone dose was significantly associated with retention (p = .005). However, Hmong required lower doses of methadone for stabilization (M = 49.0 vs. 77.1 mg; p < .0001). For both groups, positive urine drug screens were associated with stopping treatment. Further research to determine levels of tolerance and psychosocial and pharmacogenetic factors contributing to differences in methadone treatment outcome and dosing in Hmong may provide further insight into opiate addiction and its treatment.

A transnational study of migration and smoking behavior in the Mexican-origin population

OBJECTIVES

We examined migration-related changes in smoking behavior in the transnational Mexican-origin population.

METHODS

We combined epidemiological surveys from Mexico (Mexican National Comorbidity Survey) and the United States (Collaborative Psychiatric Epidemiology Surveys). We compared 4 groups with increasing US contact with respect to smoking initiation, persistence, and daily cigarette consumption: Mexicans with no migrant in their family, Mexicans with a migrant in their family or previous migration experience, migrants, and US-born Mexican Americans.

RESULTS

Compared with Mexicans with a migrant in their family or previous migration experience, migrants were less likely to initiate smoking (odds ratio [OR] = 0.56; 95% confidence interval [CI] = 0.38, 0.83) and less likely to be persistent smokers (OR = 0.41; 95% CI = 0.26, 0.63). Among daily smokers, the US-born smoked more cigarettes per day than did Mexicans with a migrant in their family or previous migration experience for men (7.8 vs 6.5) and women (8.6 vs 4.3).

CONCLUSIONS

Evidence suggests that smoking is suppressed among migrants relative to the broader transnational Mexican-origin population. The pattern of low daily cigarette consumption among US-born Mexican Americans, noted in previous research, represents an increase relative to smokers in Mexico.

Asthma Research for All of the United States

Asthma disproportionally affects different ethnic/racial groups, with Puerto Ricans and African Americans suffering the highest asthma prevalence and morbidity, Mexicans the lowest, and non-Hispanic whites in between. Genome-wide association studies of asthma have found both shared and race/ethnic-specific genetic risks factors for asthma. However, the majority of genetic asthma research is performed in populations of European descent, which limits the benefits of genetic research to European populations. It is important to biomedical and clinical research to include more diverse and underrepresented populations. The rich genetic diversity of all populations can be leveraged to scientific advantage. For example, admixture mapping provides a more powerful approach than traditional genome-wide allelic association studies in discovering genetic associations for complex diseases. By being more inclusive we can achieve a better understanding of the genetics of asthma, address health disparities, and ensure that scientific advances will benefit populations worldwide.

CYP2A6 and CYP2B6 genetic variation and its association with nicotine metabolism in South Western Alaska Native people

OBJECTIVES

Alaska Native (AN) people have a high prevalence of tobacco use and associated morbidity and mortality when compared with the general USA population. Variations in the CYP2A6 and CYP2B6 genes, encoding enzymes responsible for nicotine metabolic inactivation and procarcinogen activation, have not been characterized in AN and may contribute toward the increased risk.

METHODS

AN people (n=400) residing in the Bristol Bay region of South Western Alaska were recruited for a cross-sectional study on tobacco use. They were genotyped for CYP2A6*1X2A, *1X2B, *1B, *2, *4, *7, *8, *9, *10, *12, *17, *35 and CYP2B6*4, *6, *9 and provided plasma and urine samples for the measurement of nicotine and metabolites.

RESULTS

CYP2A6 and CYP2B6 variant frequencies among the AN Yupik people (n=361) were significantly different from those in other ethnicities. Nicotine metabolism [as measured by the plasma and urinary ratio of metabolites trans-3'-hydroxycotinine to cotinine (3HC/COT)] was significantly associated with CYP2A6 (P<0.001), but not CYP2B6 genotype (P=0.95) when controlling for known covariates. It was noteworthy that the plasma 3HC/COT ratios were high in the entire Yupik people, and among the Yupik CYP2A6 wild-type participants, they were substantially higher than those in previously characterized racial/ethnic groups (P<0.001 vs. Caucasians and African Americans).

CONCLUSION

Yupik AN people have a unique CYP2A6 genetic profile that associated strongly with in-vivo nicotine metabolism. More rapid CYP2A6-mediated nicotine and nitrosamine metabolism in the Yupik people may modulate the risk of tobacco-related diseases.

Nicotine vaccines to assist with smoking cessation: current status of research

Tobacco smoking causes cardiovascular, respiratory and malignant disease, and stopping smoking is among the key medical interventions to lower the worldwide burden of these disorders. However, the addictive properties of cigarette smoking, including nicotine inhalation, render most quit attempts unsuccessful. Recommended therapies, including combinations of counselling and medication, produce long-term continuous abstinence rates of no more than 30%. Thus, more effective treatment options are needed.

An intriguing novel therapeutic concept is vaccination against nicotine. The basic principle of this approach is that, after entering the systemic circulation, a substantial proportion of nicotine can be bound by antibodies. Once bound to antibodies, nicotine is no longer able to cross the blood-brain barrier. As a consequence, the rewarding effects of nicotine are diminished, and relapse to smoking is less likely to occur. Animal studies indicate that antibodies profoundly change the pharmacokinetics of the drug and can interfere with nicotine self-administration and impact on the severity of withdrawal symptoms. To date, five phase I/II clinical trials using vaccines against nicotine have been published. Results have been disappointing in that an increase in quit rates was only observed in small groups of smokers displaying particularly high antibody titres.

The failure of encouraging preclinical data to completely translate to clinical studies may be partially explained by shortcomings of animal models of addiction and an incomplete understanding of the complex physiological and behavioural processes contributing to tobacco addiction. This review summarizes the current status of research and suggests some directions for the future development of vaccines against nicotine. Ideally, these vaccines could one day become part of a multifaceted approach to treating tobacco addiction that includes counselling and pharmacotherapy.

A systematic review of smoking cessation intervention studies in China

INTRODUCTION

China has the highest number of tobacco smokers among the world's nations; however, no systematic review has been conducted of clinical trials on the efficacy of smoking cessation interventions in China. This paper summarizes findings of studies in order to compare the effect of pharmacotherapy, counseling, and Traditional Chinese Medicine (TCM) approaches on the abstinence rate.

METHODS

Clinical trials of smoking cessation interventions published in English or Chinese were extracted from an electronic search of PubMed and WanFang databases. The search yielded 234 studies from the PubMed and 78 studies from the WanFang.

RESULTS

Twenty-nine studies were included in this review. Of these, 11 (37.9%) were randomized controlled trials (RCTs) that assessed the following approaches: counseling (5 studies), TCM (3 studies), pharmacotherapy (1 study), a combination of pharmacotherapy and counseling (1 study), and physician advice (1 study). Pharmacotherapy alone or in combination with counseling generally resulted in a higher abstinence rate than counseling alone. TCM techniques such as acupuncture and ear point seed pressure yielded a much higher abstinence rate than pharmacotherapy and counseling. Findings are inconclusive, however, because most of the TCM studies were noncontrolled trials and did not provide a definition of "abstinence." Findings on the effectiveness of physician advice to quit smoking were also inconclusive.

CONCLUSIONS

A review of smoking cessation studies revealed that pharmacotherapy was effective in China. More RCTs of TCM approaches and physician advice are needed with long-term follow-up assessments and biochemical verification of self-reported abstinence before these approaches are adopted as evidence-based smoking cessation interventions in China.

Common polymorphisms in FMO1 are associated with nicotine dependence

BACKGROUND

Cigarette smoking and other forms of tobacco use are the leading cause of preventable mortality in the world. A better understanding of the etiology of nicotine addiction may help to increase the success rate of cessation and to decrease the massive morbidity and mortality associated with smoking.

METHODS

To identify genetic polymorphisms that contribute to nicotine dependence, our group undertook a genetic association study including three enzyme families that potentially influence nicotine metabolism: cytochrome P450 enzymes, flavin monooxygenases (FMOs), and UDP-glucuronosyl transferases.

RESULTS

Several polymorphisms in FMO1 showed association in a discovery sample, and were tested in an independent replication sample. One polymorphism, rs10912765, showed an association that remained significant after Bonferroni correction (nominal P=0.0067, corrected P=0.0134). Several additional polymorphisms in linkage disequilibrium with this single nucleotide polymorphism also showed association. Subsequent in-vitro experiments characterized FMO1 as a more efficient catalyst of nicotine N-oxidation than FMO3. In adult humans, FMO1 is primarily expressed in the kidney and is likely to be a major contributor to the renal metabolism and clearance of therapeutic drugs. FMO1 is also expressed in the brain and could contribute to the nicotine concentration in this tissue.

CONCLUSION

These findings suggest that polymorphisms in FMO1 are significant risk factors in the development of nicotine dependence and that the mechanism may involve variation in nicotine pharmacology.

Ethnicity and risk of hospitalization for asthma and chronic obstructive pulmonary disease

PURPOSE

To identify ethnic differences for risk of hospitalization for asthma and chronic obstructive pulmonary disease (COPD).

METHODS

We undertook a cohort study with 126,019 participants: 55% whites, 27% blacks, 11% Asians, and 4% Hispanics. To estimate asthma and COPD risk, we used Cox proportional hazards models adjusted for age, sex, body mass index, education, smoking, and alcohol intake. End points were hospitalizations for asthma or COPD.

RESULTS

Compared with whites, relative risks (RR) with 95% confidence intervals (95% CI) for asthma among other groups were: blacks, 1.7 (1.4-2.0); Hispanics, 0.9 (0.6-1.4); and Asians, 1.6 (1.2-2.1). Among Asians, increased risk was concentrated in Filipino men and women and South Asian men. For COPD, whites were at highest risk; RR of blacks was 0.9 (0.7-1.0); Hispanics, 0.6 (0.3- 0.9); and Asians, 0.4 (0.3-0.6). COPD risk among Asians was lowest in Chinese with RR of 0.3 (0.1-0.5).

CONCLUSIONS

Ethnic disparities in risk of asthma and COPD as well as between both diseases exist, especially for Asian Americans, who have high asthma risk and low COPD risk. While residual confounding for smoking or other environmental factors could be partially responsible, genetic factors in Asians may be involved in decreased COPD risk.

A review of tobacco use treatments in U.S. ethnic minority populations

BACKGROUND

Tobacco use is the leading preventable cause of disease and death in the United States. Among racial and ethnic minorities, disparities in tobacco use, knowledge of health risks and treatment resources, and access to and utilization of treatment contribute to a disproportionate disease burden from tobacco use. Furthermore, racial and ethnic minorities have been underrepresented within tobacco treatment studies.

PURPOSE/OBJECTIVE

This paper provides a review of published studies examining tobacco treatment interventions among ethnic and minority populations in the United States.

STUDY DESIGN/METHODS

Literature searches were used to identify smoking cessation interventions involving racial/ethnic minority populations. Identified studies were published between 1985 and 2009 involving African-American, Latino, Native American, and Asian or Pacific Islander smokers. Studies included in the review (1) targeted one or more ethnic minority group or had at least 10% of study participants from ethnic minority groups and (2) reported abstinence outcomes.

RESULTS

Sixty-four studies were included in this review. Of studies meeting inclusion criteria, 28 included a primary focus on African-Americans, 10 focused on Latinos, 4 focused on Native Americans, and 3 focused on Asian-American smokers. An additional 19 studies reported samples including participants from more than one minority group. Sample inclusion criteria, intervention content and duration, follow-up, abstinence assessment, and limitations of these studies were reviewed.

CONCLUSIONS

Individuals from racial and ethnic minority populations are interested in stopping smoking and willing to participate in treatment research. Variations in the content of treatment intervention and study design produced a range of abstinence outcomes across studies. Additional research is needed for all groups, including African-American smokers, and special attention is warranted for Latino, Native American, and Asian groups given the paucity of published studies. Although there were limited evaluations of pharmacotherapy, the existing data support use of pharmacotherapy in addition to counseling for enhancing abstinence outcomes. Further attention to level of individual smoking, variability in smoking patterns, and use of other tobacco products is needed, given known variation within and between racial and ethnic groups. Overall, findings are consistent with recommendations from the 2008 Clinical Practice Guidelines calling for increased research devoted to evaluating and enhancing tobacco use treatment interventions among racial and ethnic minority populations.

Associations of CYP2A6 genotype with smoking behaviors in southern China

AIMS

To investigate the association of CYP2A6 genetic polymorphisms with smoking-related phenotypes in Chinese smokers.

DESIGN

Case-only genetic association study.

SETTING

Southern China.

PARTICIPANTS

A total of 1328 Han Chinese smokers who participated in a community-based chronic disease screening project in Guangzhou and Zhuhai from 2006 to 2007.

MEASUREMENTS

All participants answered a structured questionnaire about socio-demographic status and smoking behaviors and informative alleles were genotyped for the cytochrome P450 2A6 (CYP2A6) gene (CYP2A6*4,*5,*7,*9 and *10).

FINDINGS

The frequencies of CYP2A6*4, *5, *7, *9 and *10 alleles were 8.5, 1.2, 6.3, 13.5 and 2.4%, which corresponded to 48.9, 15.4, 24.2 and 11.5% of participants being classified as normal, intermediate, slow and poor metabolizers, respectively. Multivariate analyses in male smokers demonstrated that compared with normal metabolizers, poor metabolizers reported smoking fewer cigarettes per day [adjusted odds ratio (OR) = 0.49; 95% confidence interval (CI): 0.32-0.76], started smoking regularly later in life (adjusted OR = 1.55; 95% CI: 1.06-2.26) and, among former smokers, reported smoking for a shorter duration prior to quitting (adjusted OR = 0.33; 95% CI: 0.12-0.94). However, poor metabolizers were less likely to quit smoking and remain abstinent than normal metabolizers (adjusted OR = 0.54; 95% CI: 0.34-0.86).

CONCLUSIONS

Reduced metabolism function of cytochrome P450 2A6 in smokers appears to be associated with fewer cigarettes smoked, later initiation of smoking regularly, shorter smoking duration and lower likelihood of smoking cessation.

Absorption, distribution, metabolism and excretion pharmacogenomics of drugs of abuse

Pharmacologic and toxic effects of xenobiotics, such as drugs of abuse, depend on the genotype and phenotype of an individual, and conversely on the isoenzymes involved in their metabolism and transport. The current knowledge of such isoenzymes of frequently abused therapeutics such as opioids (oxycodone, hydrocodone, methadone, fentanyl, buprenorphine, tramadol, heroin, morphine and codeine), anesthetics (γ-hydroxybutyric acid, propofol, ketamine and phencyclidine) and cognitive enhancers (methylphenidate and modafinil), and some important plant-derived hallucinogens (lysergide, salvinorin A, psilocybin and psilocin), as well as of nicotine in humans are summarized in this article. The isoenzymes (e.g., cytochrome P450, glucuronyltransferases, esterases and reductases) involved in the metabolism of drugs and some pharmacokinetic data are discussed. The relevance of such data is discussed for predicting possible interactions with other xenobiotics, understanding pharmacokinetic behavior and pharmacogenomic variations, assessing toxic risks, developing suitable toxicological analysis procedures, and finally for interpretating drug testing results.

Nicotine reduction revisited: science and future directions

Regulation of nicotine levels in cigarettes and other tobacco products is now possible with the passage of the Family Smoking Prevention and Tobacco Control Act (FSPTCA) in 2009, giving the US Food and Drug Administration (FDA) authority to regulate tobacco products, and with Articles 9-11 of the WHO Framework Convention on Tobacco Control. Both regulatory approaches allow establishing product standards for tobacco constituents, including nicotine. The FSPTCA does not allow nicotine levels to be decreased to zero, although the FDA has the authority to reduce nicotine yields to very low, presumably non-addicting levels. The proposal to reduce levels of nicotine to a level that is non-addicting was originally suggested in 1994. Reduction of nicotine in tobacco products could potentially have a profound impact on reducing tobacco-related morbidity and mortality. To examine this issue, two meetings were convened in the US with non-tobacco-industry scientists of varied disciplines, tobacco control policymakers and representatives of government agencies. This article provides an overview of the current science in the area of reduced nicotine content cigarettes and key conclusions and recommendations for research and policy that emerged from the deliberations of the meeting members.

Smoking during pregnancy and risk of abnormal glucose tolerance: a prospective cohort study

BACKGROUND

Disturbances in glucose metabolism during pregnancy are associated with negative sequalae for both mother and infant. The association between smoking and abnormal glucose tolerance (AGT) remains controversial. Therefore, the aim of this study was to examine the relationship between smoking prior to and during pregnancy and risk of AGT.

METHODS

We utilized data from a prospective cohort of 1,006 Hispanic (predominantly Puerto Rican) prenatal care patients in Western Massachusetts. Women reported pre- and early pregnancy smoking at recruitment (mean = 15 weeks) and mid pregnancy smoking at a second interview (mean = 28 weeks). AGT was defined as > 135 mg/dL on the routine 1-hour glucose tolerance test (1-hr OGTT). We used multivariable regression to assess the effect of pre, early, and mid-pregnancy smoking on risk of AGT and screening plasma glucose value from the 1-hr OGTT.

RESULTS

In age-adjusted models, women who smoked > 0-9 cigarettes/day in pre-pregnancy had an increased risk of AGT (OR = 1.90; 95% CI 1.02-3.55) compared to non-smokers; this was attenuated in multivariable models. Smoking in early (OR = 0.48; 95% CI 0.21-1.10) and mid pregnancy (OR = 0.38; 95% CI 0.13-1.11) were not associated with AGT in multivariable models. Smoking during early and mid pregnancy were independently associated with lower glucose screening values, while smoking in pre-pregnancy was not.

CONCLUSIONS

In this prospective cohort of Hispanic women, we did not observe an association between smoking prior to or during pregnancy and risk of AGT. Findings from this study, although based on small numbers of cases, extend prior research to the Hispanic population.

Carbamazepine but not valproate induces CYP2A6 activity in smokers with mental illness

BACKGROUND

Antiepileptic drugs (AED) are being increasingly used in the management of serious mental illness, but their effects on nicotine metabolism have not been studied.

METHODS

This study investigated the effects of three AEDs (carbamazepine, oxcarbazepine, and valproic acid) on nicotine and nicotine metabolite levels in 149 smokers with schizophrenia and bipolar disorder who participated in an afternoon blood draw for nicotine, cotinine, and 3'-hydroxycotinine (3HC). The ratio of 3HC to cotinine was calculated as a marker of CYP2A6 metabolic activity. Among the participants, 8 smokers were taking carbamazepine, 6 were taking oxcarbazepine, and 40 were taking valproic acid.

RESULTS

The 3HC/cotinine ratio was significantly higher in individuals taking carbamazepine or oxcarbazepine (combined, n = 14) versus those not taking either (mean 0.993 versus 0.503; P < 0.001). The cotinine/cigarette per day ratio was significantly lower in individuals taking carbamazepine or oxcarbazepine. The 3HC/cotinine ratios were also significantly higher in the subgroup of individuals taking carbamazepine (n = 8) versus those not taking it. There were no significant differences in nicotine or cotinine levels or 3HC/cotinine ratios in individuals taking valproic acid versus those not taking it. We conducted backward stepwise linear regression models to identify predictors of the log transformed 3HC/cotinine ratios. Taking carbamazepine and number of cigarettes smoked per day were significant determinants of log 3HC/cotinine.

CONCLUSIONS

Carbamazepine likely induces hepatic metabolism via CYP2A6 and is associated with increased 3HC/cotinine ratios.

IMPACT

Increased nicotine metabolism in individuals using AED has implications for increased smoking behavior and exposure to more tobacco toxins, which warrants further study.

UGT2B10 genotype influences nicotine glucuronidation, oxidation, and consumption

BACKGROUND

Tobacco exposure is routinely assessed by quantifying nicotine metabolites in plasma or urine. On average, 80% of nicotine undergoes C-oxidation to cotinine. However, interindividual variation in nicotine glucuronidation is substantial, and glucuronidation accounts for from 0% to 40% of total nicotine metabolism. We report here the effect of a polymorphism in a UDP-glucuronsyltransferase, UGT2B10, on nicotine metabolism and consumption.

METHODS

Nicotine, cotinine, their N-glucuronide conjugates, and total trans-3'-hydroxycotinine were quantified in the urine (n = 327) and plasma (n = 115) of smokers. Urinary nicotine N-oxide was quantified in 105 smokers. Nicotine equivalents, the sum of nicotine and all major metabolites, were calculated for each smoker. The relationship of the UGT2B10 Asp67Tyr allele to nicotine equivalents, N-glucuronidation, and C-oxidation was determined.

RESULTS

Individuals heterozygous for the Asp67Tyr allele excreted less nicotine or cotinine as their glucuronide conjugates than did wild-type, resulting in a 60% lower ratio of cotinine glucuronide to cotinine, a 50% lower ratio of nicotine glucuronide to nicotine, and increased cotinine and trans-3'-hydroxycotinine. Nicotine equivalents, a robust biomarker of nicotine intake, were lower among Asp67Tyr heterozygotes compared with individuals without this allele: 58.2 (95% confidence interval, 48.9-68.2) versus 69.2 nmol/mL (95% confidence interval, 64.3-74.5).

CONCLUSIONS

Individuals heterozygous for UGT2B10 Asp67Tyr consume less nicotine than do wild-type smokers. This striking observation suggests that variations in nicotine N-glucuronidation, as reported for nicotine C-oxidation, may influence smoking behavior.

IMPACT

UGT2B10 genotype influences nicotine metabolism and should be taken into account when characterizing the role of nicotine metabolism on smoking.

A review of the clinical pharmacokinetics of opioids, benzodiazepines, and antimigraine drugs delivered intranasally

BACKGROUND

Interest in the development of drug-delivery devices that might improve treatment compliance is growing. A dosage formulation that is easy to use, such as intranasal application with transmucosal absorption, may offer advantages compared with other routes of drug delivery. The literature concerning intranasal application is diffuse, with a large number of published studies on this topic. Some cerebroactive pharmaceuticals delivered intranasally might follow the pathway from the nose to the systemic circulation to the brain. To determine the suitability of these drugs for intranasal drug delivery, a systematic review was performed.

OBJECTIVE

The aim of this review was to compare the pharmacokinetic properties of intranasal, intravenous, and oral formulations in 3 classes of cerebroactive drugs that might be suitable for intranasal delivery-opioids, benzodiazepines, and antimigraine agents.

METHODS

A search of MEDLINE, PubMed, Cumulative Index of Nursing and Allied Health Literature, EMBASE, and Cochrane Database of Systematic Reviews (dates: 1964-April 2009) was conducted for pharmacokinetic studies of drugs that might be suitable for intranasal delivery. A comparison of pharmacokinetic data was made between these 3 routes of administration.

RESULTS

A total of 45 studies were included in this review. Most of the opioids formulated as an intranasal spray reached a T(max) within 25 minutes. The bioavailability of intranasal opioids was high; in general, >50% compared with opioids administered intravenously. Intranasal benzodiazepines had an overall T(max) that varied from 10 to 25 minutes, and bioavailability was between 38% and 98%. T(max) for most intranasal antimigraine drugs varied from 25 to 90 minutes. Intranasal bioavailability varied from 5% to 40%.

CONCLUSIONS

This review found that intranasal administration of all 3 classes of drugs was suitable for indications of rapid delivery, and that the pharmacokinetic properties differed between the intranasal, oral, and intravenous formulations (intravenous > intranasal > oral).

Elevated lung cancer risk is associated with deficiencies in cell cycle checkpoints: genotype and phenotype analyses from a case-control study

Cell cycle checkpoints play critical roles in the maintenance of genomic integrity and inactivation of checkpoint genes are frequently perturbed in most cancers. In a case-control study of 299 non-small cell lung cancer cases and 550 controls in Baltimore, we investigated the association between gamma-radiation-induced G(2)/M arrest in cultured blood lymphocytes and lung cancer risk, and examined genotype-phenotype correlations between genetic polymorphisms of 20 genes involving in DNA repair and cell cycle control and gamma-radiation-induced G(2)/M arrest. The study was specifically designed to examine race and gender differences in risk factors. Our data indicated that a less efficient DNA damage-induced G(2)/M checkpoint was associated with an increased risk of lung cancer in African American women with an adjusted odds ratio (OR) of 2.63 (95% CI = 1.01-7.26); there were no statistically significant associations for Caucasians, or African American men. When the African American women were categorized into quartiles, a significant reverse trend of decreased G(2)/M checkpoint function and increased lung cancer risk was present, with lowest-vs.-highest quartile OR of 13.72 (95% CI = 2.30-81.92, p(trend) < 0.01). Genotype-phenotype correlation analysis indicated that polymorphisms in ATM, CDC25C, CDKN1A, BRCA2, ERCC6, TP53, and TP53BP1 genes were significantly associated with the gamma-radiation-induced G(2)/M arrest phenotype. This study provides evidence that a less efficient G(2)/M checkpoint is significantly associated with lung cancer risk in African American women. The data also suggested that the function of G(2)/M checkpoint is modulated by genetic polymorphisms in genes involved in DNA repair and cell cycle control.

Novel pharmacological approaches to drug abuse treatment

The field of pharmacologic addiction treatment is expanding rapidly. While there are currently several FDA-approved medications for nicotine, alcohol, and opiate dependence, research into novel pharmacological approaches for these and additional substances is legion. Each drug of abuse, while sharing a common final neural pathway of increasing dopaminergic tone, has unique and individual characteristics that are important in developing improved and varied treatments. In this chapter, we discuss such research and present the neurobiological underpinnings of these explorations. In general, addiction treatment is focused on four areas: (1) reducing withdrawal discomfort, (2) diminishing cravings, (3) blocking rewarding effects of the drug, and (4) treating comorbidities, such as depression or ADHD. We present current ideas in pharmacologic research for nicotine, alcohol, cannabis, stimulants, and opiates.

A systems biology network model for genetic association studies of nicotine addiction and treatment

OBJECTIVE

Interpreting genome-scale genetic association data, particularly for complex diseases and phenotypes, requires extensive use of prior knowledge across a broad range of potential biological and environmental influences, spanning many scientific subdisciplines. We suggest that known or hypothesized disease risk factors, and causal mechanisms, can be represented using an ontology, a computational specification of a set of concepts and the relations between them.

METHODS

We have integrated the expertise of multiple investigators in nicotine pharmacokinetics and pharmacodynamics, nicotine dependence, and clinical smoking cessation outcomes, and represented this knowledge in an ontology-based network model. Our model spans multiple scales, from molecules, genes and cellular pathways, to complex behavioral phenotypes and even environmental factors. To leverage previous and ongoing work in the field of ontology development, we adopt, expand upon and relate elements from existing ontologies whenever possible.

RESULTS

We discuss several applications of our ontology: to support interdisciplinary research by graphically representing a complex scientific theory, to facilitate meta-analysis across different studies, to highlight potential interactions, and to support statistical analysis and causal modeling. We demonstrate that our ontology can focus hypothesis testing on areas supported by current theory.

CONCLUSION

We describe how an ontology-based computational representation can be applied to disease risk factors and mechanisms, enabling the use of prior knowledge in large-scale genetic association studies in general. In specific, we have developed an initial Smoking Behavior Risk Ontology to support studies related to the pharmacogenetics of nicotine addiction and treatment.

Where there's smoke, there's fire: high prevalence of smoking among some sub-populations and recommendations for intervention

In Australia, the prevalence of smoking is higher among certain sub-populations compared to the general population. These sub-populations include Aboriginal and Torres Strait Islander people, people from culturally and linguistically diverse backgrounds, as well as people with mental and substance use disorders and prisoners. The aims of this paper are to: describe the high prevalence of smoking among these particular sub-populations and harms associated with smoking; explore possible reasons for such high prevalence of smoking; review the evidence regarding the efficacy of existing smoking cessation interventions; and make recommendations for smoking interventions and further research among these groups. In addition to low socio-economic status, limited education and other factors, there are social, systems and psychobiological features associated with the high prevalence of smoking in these sub-groups. General population-based approaches to reducing smoking prevalence have been pursued for decades with great success and should be continued with further developments that aim specifically to affect Aboriginal and Torres Strait Islander people and some cultural groups. However, increasing attention, more specific targeting and flexible goals and interventions are also required for these and other distinct sub-populations with high smoking prevalence. Recommendations include: more funding and increased resources to examine the most appropriate education and treatment strategies to promote smoking cessation among people from Aboriginal and Torres Strait Islander and some culturally and linguistically diverse backgrounds; larger and better-designed studies evaluating smoking cessation/reduction interventions among distinct sub-groups; and system-wide interventions requiring strong leadership among clients and staff within mental health, drug and alcohol and prison settings.

Pharmacology of nicotine: addiction, smoking-induced disease, and therapeutics

Nicotine sustains tobacco addiction, a major cause of disability and premature death. Nicotine binds to nicotinic cholinergic receptors, facilitating neurotransmitter release and thereby mediating the complex actions of nicotine in tobacco users. Dopamine, glutamate, and gamma aminobutyric acid release are particularly important in the development of nicotine dependence, and corticotropin-releasing factor appears to contribute to nicotine withdrawal. Nicotine dependence is highly heritable. Genetic studies indicate roles for nicotinic receptor subtypes, as well as genes involved in neuroplasticity and learning, in development of dependence. Nicotine is primarily metabolized by CYP 2A6, and variability in rate of metabolism contributes to vulnerability to tobacco dependence, response to smoking cessation treatment, and lung cancer risk. Tobacco addiction is much more common in persons with mental illness and substance abuse disorders, representing a high proportion of current smokers. Pharmacotherapeutic approaches to tobacco addiction include nicotine replacement, bupropion, and varenicline, the latter a selective nicotine receptor partial agonist.

Tobacco taxes and regressivity

Recent literature on tobacco taxation suggests that optimal tax rates should be very high. But such high taxes raise concerns over regressivity. Most econometric estimates of elasticities by income group use historic price data that are low, and the usefulness of such estimates is therefore questionable on account of the serious 'out of sample' prediction problem. To address that problem, this paper estimates price elasticities for different socioeconomic groups using recent Canadian survey data for a period during which prices rose to a level of about $7 per pack. The results provide little reason to overturn the traditional concerns about regressivity.

Intermittent and light daily smoking across racial/ethnic groups in the United States

INTRODUCTION

Limited research exists examining the prevalence of intermittent (nondaily) and light daily (1-5 cigarettes/day) smoking across racial/ethnic groups in the United States using nationally representative data. These analyses would be informative in guiding targeted cessation strategies.

METHODS

Using logistic regression models controlling for age, gender, and education, we examined the prevalence of intermittent and light daily consumption among current smokers across racial/ethnic groups from the 2003 Tobacco Use Supplement to the Current Population Survey. We also examined the association of these demographic factors with consumption within each racial/ethnic group separately.

RESULTS

Black (odds ratio [OR] = 1.82, 95% CI = 1.59-2.07), Asian/Pacific Islander (OR = 1.62, 95% CI = 1.29-2.04), and Hispanic/Latino (OR = 3.2, 95% CI = 2.75-3.74) smokers were more likely to smoke intermittently compared with non-Hispanic Whites. Black (OR = 2.69, 95% CI = 2.27-3.18), Asian/Pacific Islander (OR = 2.99, 95% CI = 2.13-4.19), and Hispanic/Latino (OR = 4.64, 95% CI = 3.85-5.58) smokers also were more likely to have light daily consumption compared with non-Hispanic Whites. Hispanic/Latino intermittent smokers smoked fewer days per month and fewer cigarettes per day compared with non-Hispanic White smokers. We found no significant gender differences across racial/ethnic groups in intermittent smoking, but male smokers were significantly less likely to have light daily consumption for all racial/ethnic groups.

DISCUSSION

These results have implications for the understanding of the tobacco dependence, the development of prevention and cessation strategies, and the applicability of harm-reduction techniques for racial/ethnic minorities.

Light and intermittent smoking among California's Asian Americans

INTRODUCTION

Asian Americans, along with other ethnic minorities, have been described to be more likely than Whites to be light and intermittent smokers. Characterizing Asian American smoking behavior accurately on a population level requires oversampling groups of different national origin and including non-English-speaking participants.

METHODS

We analyzed the California Health Interview Survey to compare moderate/heavy (> or =10 cigarettes/day), light (0-9 cigarettes/day), and intermittent (not daily) smoking patterns in Asian Americans with those of Whites. We also examined whether social and demographic factors that had been associated with Asian American smoking prevalence also were associated with light and intermittent smoking patterns in each of the national origin groups.

RESULTS

Most Asian American smokers were more likely to be light and intermittent smokers (range = 36.6%-61.5% for men and 29.9%-81.5% for women) compared with Whites, with lower mean cigarette consumption. Asian American light and intermittent smokers were more likely than moderate/heavy smokers to be women (odds ratio [OR] = 2.12, 95% CI = 1.14-3.94), highly educated (OR = 3.16, 95% CI = 1.21-8.28), not Korean (compared with Chinese; OR = 0.32, 95% CI = 0.13-0.79), and bilingual speakers with high English language proficiency compared with English-only speakers (OR = 2.83, 95% CI = 1.21-6.84). Asian American intermittent smokers were more likely than daily smokers to be women (OR = 2.25, 95% CI = 1.08-4.72) and to have lower household income.

DISCUSSION

The predominance of Asian American light and intermittent smoking patterns has important implications for developing effective tobacco control outreach. Further studies are needed to elaborate the relationship between biological, psychosocial, and cultural factors influencing Asian American smoking intensity.