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

Precision treatment with nicotine in autosomal dominant sleep-related hypermotor epilepsy (ADSHE): An observational study of clinical outcome and serum cotinine levels in 17 patients

PURPOSE

To report the clinical outcome of nicotine exposure in patients with autosomal dominant sleep-related hypermotor epilepsy (ADSHE), along with serum concentrations of the major nicotine metabolite cotinine.

METHODS

We recruited 17 ADSHE patients with CHRNA4 mutations (12 with p.S280F and 5 with p.L291 dup). Clinical characteristics were collected from hospital records. A telephone interview was performed on the use and seizure-reducing effect of nicotine applying a six-point rating scale from "none" to very good". Serum concentrations of cotinine were measured in 14 nicotine users.

RESULTS

All patients but one had ever used nicotine. Nine had used snuff; seven were current users. Eleven had used transdermal nicotine; nine were current users. Seven reported long-lasting seizure control, all used nicotine, four transdermal nicotine and three snuff. In 78% of patients using continuous transdermal nicotine, the effect was rated as good or very good. Cotinine concentrations were 453 ± 196 (mean ± SD) nmol/l in seven patients using transdermal nicotine only vs. 1241 ± 494 nmol/l in seven using other forms of nicotine. No correlation with seizure control was found. Three patients experienced improvement with transdermal delivery compared to snuff.

CONCLUSION

This is the hitherto largest observational study supporting a favorable effect of nicotine in this specific seizure disorder. Better seizure control from transdermal nicotine compared to only day-time consumption suggests benefit from exposure throughout the night. According to current clinical experience, patients with uncontrolled ADSHE harboring relevant mutations should be offered precision treatment with transdermal nicotine.

Comparing the Rate of Nicotine Metabolism Among Smokers With Current or Past Major Depressive Disorder

BACKGROUND AND OBJECTIVES

Persons with current or past major depressive disorder (MDD) vs those without have higher smoking rates. The nicotine metabolite ratio (NMR) represents variation in the rate of nicotine metabolism and has been associated with smoking behaviors and response to tobacco treatments. We compared NMR between smokers with current or past MDD (MDD+) vs smokers without MDD (MDD-). We also assessed correlates of NMR and compared withdrawal and craving between MDD+ and MDD- smokers.

METHODS

Using baseline data from two clinical trials and propensity score weighting based on sex, race, body mass index, and smoking rate, we compared NMR between MDD+ (N = 279) and MDD- (N = 1575) smokers. We also compared groups on and nicotine withdrawal and craving.

RESULTS

Mean NMR (β = -.02, 95% confidence interval [CI]: -0.05 to 0.01, P = .13) and the distribution of smokers across NMR quartiles (odds ratio [OR] = 0.76, 95% CI: 0.50 to 1.16, P = .21) were similar between MDD+ and MDD- samples. This relationship was not affected by antidepressant medication. In the MDD+ sample, African Americans had significantly lower mean NMR, while older smokers and smokers with lower education had higher mean NMR (Ps < .05). MDD+ smokers had significantly higher withdrawal and craving than MDD- smokers (Ps < .05).

DISCUSSION AND CONCLUSIONS

While variability in NMR may not explain differences in smoking rates between MDD+ and MDD- smokers, MDD+ smokers report increased withdrawal and craving.

SCIENTIFIC SIGNIFICANCE

In this first study to assess NMR among MDD+ smokers, the findings underscore the need to address withdrawal and craving within smoking cessation treatments for those with MDD. (Am J Addict 2021;00:00-00).

Inhibition and induction of CYP enzymes in humans: an update

The cytochrome P450 (CYP) enzyme family is the most important enzyme system catalyzing the phase 1 metabolism of pharmaceuticals and other xenobiotics such as herbal remedies and toxic compounds in the environment. The inhibition and induction of CYPs are major mechanisms causing pharmacokinetic drug–drug interactions. This review presents a comprehensive update on the inhibitors and inducers of the specific CYP enzymes in humans. The focus is on the more recent human in vitro and in vivo findings since the publication of our previous review on this topic in 2008. In addition to the general presentation of inhibitory drugs and inducers of human CYP enzymes by drugs, herbal remedies, and toxic compounds, an in-depth view on tyrosine-kinase inhibitors and antiretroviral HIV medications as victims and perpetrators of drug–drug interactions is provided as examples of the current trends in the field. Also, a concise overview of the mechanisms of CYP induction is presented to aid the understanding of the induction phenomena.

A Physiologically Based Pharmacokinetic Model for Pregnant Women to Predict the Pharmacokinetics of Drugs Metabolized Via Several Enzymatic Pathways

BACKGROUND

Physiologically based pharmacokinetic modeling is considered a valuable tool for predicting pharmacokinetic changes in pregnancy to subsequently guide in-vivo pharmacokinetic trials in pregnant women. The objective of this study was to extend and verify a previously developed physiologically based pharmacokinetic model for pregnant women for the prediction of pharmacokinetics of drugs metabolized via several cytochrome P450 enzymes.

METHODS

Quantitative information on gestation-specific changes in enzyme activity available in the literature was incorporated in a pregnancy physiologically based pharmacokinetic model and the pharmacokinetics of eight drugs metabolized via one or multiple cytochrome P450 enzymes was predicted. The tested drugs were caffeine, midazolam, nifedipine, metoprolol, ondansetron, granisetron, diazepam, and metronidazole. Pharmacokinetic predictions were evaluated by comparison with in-vivo pharmacokinetic data obtained from the literature.

RESULTS

The pregnancy physiologically based pharmacokinetic model successfully predicted the pharmacokinetics of all tested drugs. The observed pregnancy-induced pharmacokinetic changes were qualitatively and quantitatively reasonably well predicted for all drugs. Ninety-seven percent of the mean plasma concentrations predicted in pregnant women fell within a twofold error range and 63% within a 1.25-fold error range. For all drugs, the predicted area under the concentration-time curve was within a 1.25-fold error range.

CONCLUSION

The presented pregnancy physiologically based pharmacokinetic model can quantitatively predict the pharmacokinetics of drugs that are metabolized via one or multiple cytochrome P450 enzymes by integrating prior knowledge of the pregnancy-related effect on these enzymes. This pregnancy physiologically based pharmacokinetic model may thus be used to identify potential exposure changes in pregnant women a priori and to eventually support informed decision making when clinical trials are designed in this special population.

Nicotine metabolite ratio and smoking outcomes using nicotine replacement therapy and varenicline among smokers with and without psychiatric illness

INTRODUCTION

It has been suggested that the effectiveness of nicotine replacement smoking cessation pharmacotherapy may be enhanced by assessing rates of nicotine metabolism using the nicotine metabolite ratio - which reflects differences in the activity of the CYP2A6 hepatic enzyme - and titrating doses appropriately. To date, supporting evidence is equivocal, with little information regarding the assessment and effectiveness of the nicotine metabolite ratio among smokers with psychiatric conditions.

METHODS

The nicotine metabolite ratio of 499 smokers from the FLEX trial was determined using urine samples obtained at baseline. They were randomized to receive either: standard transdermal nicotine (nicotine replacement therapy); extended nicotine replacement therapy + adjunct nicotine agent; or varenicline. Primary cessation outcomes were seven-day point prevalence at 5, 10, 22, and 52 weeks post-target quit date, comparing across treatment and psychiatric status. Our principal analysis employed logistic regression (outcome: abstinence), using slow metabolizers as the reference category.

RESULTS

No differences were observed by nicotine metabolite ratio classification (slow, moderate, fast) with respect to any demographic or smoking-related variables. Nicotine metabolite ratio class did not predict smoking cessation in either the overall sample, or by treatment condition at any time-point (week 52 moderate metabolizers: odds ratio 1.34, 95% confidence interval (0.68-2.63), p=0.394; fast metabolizers: odds ratio 1.04 (0.56-1.91), p=0. 906).

CONCLUSION

Our results did not find any associations between nicotine metabolite ratio and cessation outcomes among smokers using nicotine replacement therapy or varenicline with and without lifetime psychiatric conditions.

A combined analysis of worldwide studies demonstrates an association between bipolar disorder and tobacco smoking behaviors in adults

OBJECTIVES

Worldwide studies were combined to examine two hypotheses: (i) bipolar disorder is associated with smoking behaviors, compared with the general population; and (ii) smoking behavior prevalences in bipolar disorder are intermediate between those in major depressive disorder and those in schizophrenia.

METHODS

Combined analyses used 56 articles on adults obtained from a PubMed search or the senior author's article collection. Odds ratios (ORs) and their 95% confidence intervals (CIs) compared current smoking, heavy smoking among current smokers, smoking cessation in ever smokers, and ever smoking in bipolar disorder versus control groups.

RESULTS

The combined OR was 3.5 (CI: 3.39-3.54) in 51 current smoking studies of bipolar disorder versus the general population from 16 countries. More limited data provided an OR = 0.34 (CI: 0.31-0.37) for smoking cessation and an OR = 3.6 (CI: 3.30-3.80) for ever smoking. The combined OR was 0.76 (CI: 0.74-0.79) for current smoking in bipolar disorder versus schizophrenia in 20 studies from ten countries. Ever smoking may be lower in bipolar disorder than in schizophrenia (OR = 0.83, CI: 0.75-0.91). The OR was 2.05 (CI: 2.00-2.10) for current smoking in bipolar disorder versus major depression in 18 studies from seven countries. Ever smoking may be higher (OR = 1.5, CI: 1.40-1.70) and smoking cessation lower (OR = 0.51, CI: 0.45-0.59) in bipolar disorder than in major depression.

CONCLUSIONS

Increased current smoking in bipolar disorder versus the general population reflected increased ever smoking (initiation) and decreased smoking cessation. Smoking behavior frequencies in bipolar disorder may be between those in depressive disorder and schizophrenia, with schizophrenia showing the highest severity level.

Health care professionals implementing a smoke-free policy at inpatient psychiatric units

Smoke-free grounds policies (SFGPs) were introduced to inpatient psychiatric hospital settings to improve health among patients, staff, and visitors. We conducted an ethnographic study in Northern British Columbia, Canada, to describe how the implementation of SFGPs is affected by institutional cultures. Data reported here included participant observation, document review, informal discussions (n = 11), and interviews with health care professionals (HCPs; n = 19) and staff (n = 2) at two hospitals. We used iterative and inductive processes to derive thematic findings. Findings related to HCPs illustrate how local contexts and cultural factors affect SFGP implementation. These factors included individual beliefs and attitudes, the influence of group norms, leadership and consensus building, and locale-specific norms. Strong, consultative leadership, in which leaders solicited input from and long-term support of people most directly responsible for policy implementation, was key to success.

Nicotine intake and smoking topography in smokers with bipolar disorder

OBJECTIVES

Cigarette smoking behavior in bipolar disorder (BPD), including the effects of mood-stabilizing medications, has not been well characterized.

METHODS

We compared serum nicotine, nicotine metabolite levels, and smoking topography in 75 smokers with BPD to 86 control smokers (CON). For some comparisons, an additional control group of 75 smokers with schizophrenia (SCZ) were included.

RESULTS

There were no differences between the BPD and CON groups in baseline smoking characteristics or serum nicotine or cotinine levels. Fifty-one smokers with BPD (68.9%) were taking one of the following mood stabilizers: valproic acid, lamotrigine, carbamazepine, oxcarbazepine, lithium, or topiramate. The 3-hydroxycotinine-to-cotinine ratio, a marker of cytochrome P450 2A6 (CYP2A6) metabolic activity, was significantly higher in BPD versus CON and versus SCZ (0.68 versus 0.49 versus 0.54; p =0.002). The difference between groups, however, was no longer significant when the analysis was repeated with those taking hepatic enzyme-inducing drugs (carbamazepine, oxcarbazepine, and topiramate) included as a covariate. The time between puffs, or interpuff interval (IPI), was shorter in BPD versus CON by an average of 3.0sec (p<0.05), although this was no longer significant when we removed smokers from the analysis of those taking hepatic enzyme inducers.

CONCLUSIONS

Smokers with BPD are not different from CON on most measures of nicotine intake and smoking topography. We found an increased rate of nicotine metabolism in smokers taking mood stabilizers that are hepatic enzyme inducers, including carbamazepine, oxcarbazepine, and topiramate. Smokers with rapid nicotine metabolism might be expected to smoke more intensely to compensate for the more rapid disappearance of nicotine from the blood and brain, and may have more difficulty in quitting smoking, although this requires further study.

The co-occurrence of cigarette smoking and bipolar disorder: phenomenology and treatment considerations

OBJECTIVES

  Despite recent advances in understanding the causes and treatment of nicotine dependence among individuals with psychiatric disorders, smoking among individuals with bipolar disorder (BD) has received little attention. The goal of this review is to synthesize the literature on the epidemiology, consequences, and treatment of smoking and nicotine dependence among individuals with BD and to delineate a future research agenda.

METHODS

  We conducted a PubMed search of English-language articles using the search terms bipolar disorder, mania, tobacco, nicotine, and smoking, followed by a manual search of the literature cited in the identified articles. Articles were chosen by the authors on the basis of their relevance to the topic areas covered in this selective review.

RESULTS

  Adults with BD are two to three times more likely to have started smoking and, on the basis of epidemiological data, may be less likely to initiate and/or maintain smoking abstinence than individuals without psychiatric disorders. Smoking cessation is achievable for individuals with BD, but challenges such as chronic mood dysregulation, high prevalence of alcohol and drug use, more severe nicotine dependence, and limited social support can make quitting more difficult. Effective treatments for tobacco cessation are available, but no controlled trials in smokers with BD have been conducted.

CONCLUSIONS

  Cigarette smoking is a prevalent and devastating addiction among individuals with BD and should be addressed by mental health providers. Additional research on the mechanisms of, and optimal treatment for, smoking and nicotine dependence in this population is desperately needed.