Effect of Metformin on Cigarette Withdrawal Syndrome and Abstinence in Lung Cancer Patients; A Double-blind Placebo-controlled Trial

Background: Lung cancer (LC) is a leading cause of cancer morbidity and mortality worldwide. One of the predisposing factors for LC is smoking. Metformin is the first line for diabetes treatment and is shown that it can be used for nicotine withdrawal syndrome reduction. Objectives: This study was conducted to evaluate the effects of metformin on reducing the nicotine withdrawal syndrome and increasing nicotine abstinence in patients with LC. Methods: In a randomized double-blind placebo-controlled trial from February 2018 to May 2019, 53 patients with LC were selected by respondent-driven sampling (RDS), and were assigned into two experimental and wait-list control (WLC) group through block randomization (BR). After 3 weeks of baseline assessment, metformin or placebo was prescribed in the form of escalating doses. Cigarette Withdrawal Scale (CWS-21), urinary cotinine levels, and exhaled carbon monoxide (eCO) levels were evaluated in 16 steps by the repeated measures. The primary outcomes include metformin efficacy on cigarette withdrawal syndrome and secondary outcomes include urinary cotinine levels and eCO level. The data were analyzed by generalized estimation equation (GEE), chi-square, and Atlas-Ti5. Results: The primary outcomes showed that the metformin group had significant effects on the improvement of depression, anxiety, craving, irritability, and appetite, difficulty in concentrating, appetite-weight, and insomnia during the 12-weeks treatment period (all P's < 0.05). In addition, only cravings scores remained constant until the 6-month follow-up (P < 0.05). Secondary outcomes demonstrated that urinary cotinine levels and eCO level significantly decreased in the metformin group (all P's < 0.05). However, this decrease did not remain constant at both levels until the 6-month follow-up (P > 0.05). Conclusions: Metformin had a clinical potential for reducing nicotine withdrawal. However, more studies are needed.

Altered mRNA Levels of Stress-Related Peptides in Mouse Hippocampus and Caudate-Putamen in Withdrawal after Long-Term Intermittent Exposure to Tobacco Smoke or Electronic Cigarette Vapour

Nicotine addiction is a severe public health problem. The aim of this study was to investigate the alterations in key neurotransmissions after 60 days of withdrawal from seven weeks of intermittent cigarette smoke, e-cigarette vapours, or an e-cigarette vehicle. In the nicotine withdrawal groups, increased depressive and anxiety/obsessive–compulsive-like behaviours were demonstrated in the tail suspension, sucrose preference and marble burying tests. Cognitive impairments were detected in the spatial object recognition test. A significant increase in Corticotropin-releasing factor (Crf) and Crf1 mRNA levels was observed, specifically after cigarette withdrawal in the caudate-putamen nucleus (CPu). The nociceptin precursor levels were reduced by cigarette (80%) and e-cigarette (50%) withdrawal in the CPu. The delta opioid receptor showed a significant reduction in the hippocampus driven by the exposure to an e-cigarette solubilisation vehicle, while the mRNA levels doubled in the CPu of mice that had been exposed to e-cigarettes. Withdrawal after exposure to e-cigarette vapour induced a 35% Bdnf mRNA decrease in the hippocampus, whereas Bdnf was augmented by 118% by cigarette withdrawal in the CPu. This study shows that long-term withdrawal-induced affective and cognitive symptoms associated to lasting molecular alterations in peptidergic signalling may determine the impaired neuroplasticity in the hippocampal and striatal circuitry.

Time Spent With Urges to Smoke and Strength of Urges as Independent Predictors of Self-Rated Difficulty Not Smoking During Abstinence

Self-perceived difficulty not smoking during a quit attempts is potentially an important factor mediating ability to remain abstinent during quit attempts. We investigated how far this could be explained by specific withdrawal symptoms (e.g., irritability, depressed mood, hunger etc.), strength of the urges to smoke and the time spent with urges to smoke. Thirty-five male and female smokers, who smoked at least 15 cigarettes per day were required to abstain overnight and attended the laboratory the next day and completed the Mood and Physical Symptoms Scale (MPSS), a validated questionnaire assessing cigarette withdrawal symptoms and urges to smoke. They also rated how difficult they had found it not smoking. Difficulty not smoking was independently and strongly predicted by both strength of urges to smoke and time spent with urges, but not by other withdrawal symptoms. The results support the idea that both time spent with urges and strength of urges to smoke are what primarily makes it difficult for smokers to abstain early in a quit attempt and that other withdrawal symptoms play a more modest role. Further research is needed to confirm this finding and examine how far difficulty not smoking mediates failure of quit attempts.