Methadone’s effect on nAChRs—a link between methadone use and smoking?

A determination of the aerosolization efficiency of drugs of abuse in a eutectic mixture with nicotine in electronic cigarettes

Eutectic mixtures can be formed by adding drugs other than nicotine (DOTNs) to nicotine-based e-liquids in electronic cigarettes (e-cigarettes). Thus, the interaction between nicotine e-liquids and DOTNs must be evaluated. Presented is the change in e-cigarette aerosolization of nicotine and methadone alone versus a 1:1 nicotine:methadone mixture to evaluate the possible formation of a eutectic mixture that can result in an increase of drug delivery. E-liquids were prepared in-house using 1:1 propylene glycol (PG):vegetable glycerin (VG) as a base plus nicotine, methadone hydrochloride, or 1:1 nicotine:methadone hydrochloride. The e-liquids were aerosolized via an automated vaping machine using parameters adopted from the Cooperation Centre for Scientific Research Relative to Tobacco (CORESTA) E-cigarette Task Force method. Drug recovery was determined by capturing the aerosol from 15 puffs generated by the e-cigarette. Concentrations of nicotine and methadone aerosolized were determined by gas chromatography-mass spectrometry using nicotine (n = 3), methadone (n = 3), and combined nicotine/methadone e-liquids (n = 3), each prepared in-house at 12 mg/ml. The concentration of nicotine and methadone in 15 puffs of the single drug e-liquids were determined to be 1.60 ± 0.20 and 2.67 ± 0.12 mg, respectively. The concentration of nicotine and methadone in 15 puffs of the multidrug e-liquid were determined to be 3.66 ± 0.49 and 3.65 ± 0.10 mg, respectively. The single nicotine and methadone e-liquids had recoveries of 70 ± 0.1% and 84 ± 0.1%, respectively. In the 1:1 mixture, the recovery of both drugs increased. The development of a eutectic mixture can promote aerosolization of the drug and deliver a greater dose to the user.

Heterogeneous network propagation with forward similarity integration to enhance drug-target association prediction

Identification of drug-target interaction (DTI) is a crucial step to reduce time and cost in the drug discovery and development process. Since various biological data are publicly available, DTIs have been identified computationally. To predict DTIs, most existing methods focus on a single similarity measure of drugs and target proteins, whereas some recent methods integrate a particular set of drug and target similarity measures by a single integration function. Therefore, many DTIs are still missing. In this study, we propose heterogeneous network propagation with the forward similarity integration (FSI) algorithm, which systematically selects the optimal integration of multiple similarity measures of drugs and target proteins. Seven drug-drug and nine target-target similarity measures are applied with four distinct integration methods to finally create an optimal heterogeneous network model. Consequently, the optimal model uses the target similarity based on protein sequences and the fused drug similarity, which combines the similarity measures based on chemical structures, the Jaccard scores of drug-disease associations, and the cosine scores of drug-drug interactions. With an accuracy of 99.8%, this model significantly outperforms others that utilize different similarity measures of drugs and target proteins. In addition, the validation of the DTI predictions of this model demonstrates the ability of our method to discover missing potential DTIs.

Tobacco smoking is associated with more pain and worse functional outcomes after torsional ankle fracture

OBJECTIVE

The purpose of this study was to assess the impact of current and remote tobacco smoking on clinical and functional outcomes after torsional ankle fracture.

METHODS

Nine hundred thirty-five patients treated surgically for torsional ankle fracture over 9 years were reviewed. Tobacco smoking status at the time of injury was defined as current (48.3%), former (11.7%), and nonsmoker (40.0%). Complications, unplanned secondary procedures, pain medication use, and functional outcome scores, as measured by Foot Function Index and Short Musculoskeletal Function Assessment (SMFA) surveys.

RESULTS

Mean age was 44.8 years, with 50.3% male. More than 6 months following injury current smokers were more likely than former smokers and nonsmokers to report ankle pain (67.8% vs 45.8% vs 47.5%) and to use prescription pain medicines (23.0% vs 10.4% vs 6.3%), all P < .05. Multiple logistic regression found current tobacco use to be an independent predictor for prescription pain medication use, and worse scores for the Foot Function Index, SMFA Dysfunction, and SMFA Bothersome scores, all P < .05. Complications occurred in 15.5% of all patients, and 10.7% underwent unplanned secondary operations. Tobacco smoking was not associated with more complications or secondary procedures.

CONCLUSION

Current smokers are more likely to use prescription pain medications several months after injury and have worse patient-reported functional outcome scores after surgical treatment of torsional ankle fractures than former smokers and nonsmokers.

Reductions in tobacco use in naltrexone, relative to buprenorphine-maintained individuals with opioid use disorder: Secondary analysis from the National Drug Abuse Treatment Clinical Trials Network

BACKGROUND

Smoking prevalence in individuals with opioid use disorder (OUD) is over 80%. Research suggests that opioid use significantly increases smoking, which could account for the strikingly low smoking-cessation rates observed in both methadone- and buprenorphine-maintained patients, even with the use of first-line smoking-cessation interventions. If opioids present a barrier to smoking-cessation, then better smoking outcomes should be observed in OUD patients treated with extended-release naltrexone (XR-NTX, an opioid antagonist) compared to those receiving buprenorphine (BUP-NX, a partial opioid agonist).

METHODS

The current study is a secondary analysis of a 24-week, multi-site, open-label, randomized clinical trial conducted within the National Drug Abuse Treatment Clinical Trials Network comparing the effectiveness of XR-NTX vs. BUP-NX for adults with OUD. Longitudinal mixed effects models were used to determine if there was a significant reduction in cigarette use among daily smokers successfully inducted to treatment (n = 373) and a subset of those who completed treatment (n = 169).

RESULTS

Among daily smokers inducted onto OUD medication, those in the XR-NTX group smoked fewer cigarettes per day (M = 11.36, SE = 0.62) relative to smokers in the BUP-NX group (M = 13.33, SE = 0.58) across all study visits, (b (SE) = -1.97 (0.55), p < .01). Results were similar for the treatment completers.

CONCLUSIONS

OUD patients treated with XR-NTX reduced cigarette use more than those treated with BUP-NX, suggesting that XR-NTX in combination with other smoking cessation interventions might be a better choice for OUD smokers interested in reducing their tobacco use.

The Chinese version of obsessive compulsive drug use scale: validation in outpatient methadone maintenance treatment program

BACKGROUND

The Obsessive Compulsive Drug Use Scale (OCDUS) measures the overall craving level within a period from a multidimensional perspective. However, no studies have addressed the validity of the new OCDUS factor structure, presented in 2016, in China. Additionally, there is lack of evidence on the interaction among risk factors for relapse. We aimed to assess the psychometric properties of the scores of the Chinese version of the OCDUS in patients with heroin dependence receiving methadone maintenance treatment (MMT). Further, we aimed to assess the correlations of the OCDUS scores with withdrawal symptoms, depression, anxiety, and nicotine dependence.

METHODS

We enrolled 113 adults (age 32-64 years) and administered them with the OCDUS, Subjective Opioid Withdrawal Scale (SOWS), Beck Depression Inventory-II (BDI-II), State-Trait Anxiety Inventory (STAI), and Fagerstrom Test for Nicotine Dependence (FTND).

RESULTS

Exploratory factor analysis identified a 3-dimensional component that included "Frequency of craving," "Inference of heroin," and "Control of heroin." These factors showed acceptable internal consistency, adequate item-total correlations, and significant item-subscale correlations. There was no correlation between the OCUDS scores and age, education, duration of receiving MMT, and MMT dosages. However, there was a significant correlation between the OCDUS total scores and the SOWS, STAI, BDI-II, and FTND scores. The scores of all the subscales were associated with the SOWS scores; further, the scores of the first two subscales were associated with BDI-II scores while only the scores of the first subscale were associated with the FTND scores.

CONCLUSIONS

Our findings support the reliability and structure validity of the OCDUS scores. Heroin craving, withdrawal symptoms, negative emotions, and nicotine dependence, which are considered as risk factors for heroin relapse, might interact with each other. There is a need for further studies on the underlying mechanism of these clinical phenomena.

Reduced cigarette smoking during injectable extended-release naltrexone treatment for opioid use disorder

BACKGROUND

The prevalence of tobacco cigarette smoking in the US has declined to approximately 15%, yet, it remains over 90% among individuals with opioid use disorder regardless of whether they are currently using opioids illicitly or as opioid substitution therapy. This disparity raises the question of whether opioids facilitate smoking among individuals with opioid use disorder and whether opioid antagonists may reduce it.

OBJECTIVES

Determine whether injectable extended-release naltrexone (XR-NTX) treatment of opioid use disorder patients is associated with a spontaneous smoking reduction. We hypothesized that treatment with XR-NTX for would lead to a reduction in smoking in tobacco cigarette smokers with opioid use disorder.

METHODS

We analyzed data from 64 tobacco cigarette smokers (38% female) with opioid use disorder who were induced on XR-NTX for prevention of relapse to opioids. The number of cigarettes smoked per day and opioid-related craving and withdrawal were assessed at baseline and during treatment.

RESULTS

Smoking was reduced from 14.4 ± 1.0 to 9.8 ± 1.0(p < 0.001) cigarettes per day after one month and 8.6 ± 1.1 cigarettes per day after two months of treatment. Daily cigarette consumption was positively correlated with the pre-treatment frequency of opioid use and opioid-related craving during the XR-NTX treatment.

CONCLUSIONS

XR-NTX treatment in smokers with opioid use disorder was associated with a 29% decline in daily cigarette consumption. Together with prior evidence of increased smoking during opioid agonist therapy, our finding suggests a pharmacodynamic interaction between nicotine and opioid systems that could influence treatment choices in this population. Our findings merit confirmation in a prospective controlled study. (NCT02324725 and NCT01587196).

Achieving Smoking Cessation Among Persons with Opioid Use Disorder

While prevalence of tobacco use in the US general population is declining, prevalence among those with opioid use disorder (OUD) remains high and results in excessive tobacco-related disease and premature mortality. Among smokers with OUD, tobacco cessation rates are negligible without treatment. However, both low-intensity behavioral interventions and more intensive motivational interventions yield negligible cessation rates. While contingency management has potent short-term cessation effects, effects are not maintained at post-intervention follow-up. Evidence-based smoking cessation pharmacotherapies, such as nicotine replacement therapy, bupropion, and varenicline, result in very modest cessation rates among smokers with OUD. Intensification of pharmacotherapy, such as high-dose and combination nicotine replacement therapy or extended medication treatment, has failed to improve cessation outcomes compared with standard treatment regimens. Targeting the unique challenges faced by smokers with OUD, including nicotine-opioid interactions and poor medication adherence, has potential to improve cessation outcomes, but further research is needed to optimize intervention efficacy among smokers with OUD.

Nicotine Gateway Effects on Adolescent Substance Use

Given the rise in teenage use of electronic nicotine delivery systems ("vaping") in congruence with the increasing numbers of drug-related emergencies, it is critical to expand the knowledge of the physical and behavioral risks associated with developmental nicotine exposure. A further understanding of the molecular and neurochemical underpinnings of nicotine's gateway effects allows emergency clinicians to advise patients and families and adjust treatment accordingly, which may minimize the use of tobacco, nicotine, and future substances. Currently, the growing use of tobacco products and electronic cigarettes among teenagers represents a major public health concern. Adolescent exposure to tobacco or nicotine can lead to subsequent abuse of nicotine and other substances, which is known as the gateway hypothesis. Adolescence is a developmentally sensitive time period when risk-taking behaviors, such as sensation seeking and drug experimentation, often begin. These hallmark behaviors of adolescence are largely due to maturational changes in the brain. The developing brain is particularly vulnerable to the harmful effects of drugs of abuse, including tobacco and nicotine products, which activate nicotinic acetylcholine receptors (nAChRs). Disruption of nAChR development with early nicotine use may influence the function and pharmacology of the receptor subunits and alter the release of reward-related neurotransmitters, including acetylcholine, dopamine, GABA, serotonin, and glutamate. In this review, we emphasize that the effects of nicotine are highly dependent on timing of exposure, with a dynamic interaction of nAChRs with dopaminergic, endocannabinoid, and opioidergic systems to enhance general drug reward and reinforcement. We analyzed available literature regarding adolescent substance use and nicotine's impact on the developing brain and behavior using the electronic databases of PubMed and Google Scholar for articles published in English between January 1968 and November 2018. We present a large collection of clinical and preclinical evidence that adolescent nicotine exposure influences long-term molecular, biochemical, and functional changes in the brain that encourage subsequent drug abuse.

Endogenous opioid system: a promising target for future smoking cessation medications

BACKGROUND

Nicotine addiction continues to be a health challenge across the world. Despite several approved medications, smokers continue to relapse. Several human and animal studies have evaluated the role of the endogenous opioid system as a potential target for smoking cessation medications.

METHODS

In this review, studies that have elucidated the role of the mu (MORs), delta (DORs), and kappa (KORs) opioid receptors in nicotine reward, nicotine withdrawal, and reinstatement of nicotine seeking will be discussed. Additionally, the review will discuss discrepancies in the literature and therapeutic potential of the endogenous opioid system, and suggest studies to address gaps in knowledge with respect to the role of the opioid receptors in nicotine dependence.

RESULTS

Data available till date suggest that blockade of the MORs and DORs decreased the rewarding effects of nicotine, while activation of the MORs and DORs decreased nicotine withdrawal-induced aversive effects. In contrast, activation of the KORs decreased the rewarding effects of nicotine, while blockade of the KORs decreased nicotine withdrawal-induced aversive effects. Interestingly, blockade of the MORs and KORs attenuated reinstatement of nicotine seeking. In humans, MOR antagonists have shown benefits in select subpopulations of smokers and further investigation is required to realize their full therapeutic potential.

CONCLUSION

Future work must assess the influence of polymorphisms in opioid receptor-linked genes in nicotine dependence, which will help in both identifying individuals vulnerable to nicotine addiction and the development of opioid-based smoking cessation medications. Overall, the endogenous opioid system continues to be a promising target for future smoking cessation medications.