P-122 Gastrointestinal side effects of morphine in cancer pain: A comparison between the smoking and non-smoking patients

Abstract

The use of morphine analgesics is associated with a number of side effects, especially morphine-induced gastrointestinal dysfunction. Gastrointestinal side effects of morphine have a negative impact on patient quality of life. The complex relationship between nicotine and opioids is a controversial one and still not well understood. Some animal studies suggest that nicotine binds some opioid receptors. The aim of this study was to prospectively compare the incidence of gastrointestinal side effects of morphine between smokers and non-smokers in cancer pain patients. The study was conducted in our institution between 2019 and 2021. We included all patients receiving oral morphine, at least 60 mg daily, for cancer pain, for a week or longer before inclusion. All patients received oral sustained-release morphine sulfate and morphine sulfate immediate release. We used a prospective survey with a questionnaire administered weekly for 4 weeks. The participants were free of psychiatric disturbance, substance abuse (other than nicotine), had no renal or hepatic disease failure, and had no gastrointestinal disease. Patients were divided into two groups: smokers (n=40) and non-smokers (n=40). Gastrointestinal side effects of morphine were recorded and compared between the two groups. Of the 96 patients, 80 completed the entire study by answering the questionnaire on 4 consecutive occasions. There were 40 smokers and 40 non-smokers. The group of smokers was all men and the group of non-smokers had 17 men and 23 women. The mean age was 50 years (range: 26-65). The gastrointestinal side effects in the smokers group were: constipation in 20%, nausea in 18%, dry mouth in 18%, reflux in 5%, dyspepsia in 4%, anorexia in 1%, and abdominal pain in 1%. The gastrointestinal side effects in the non-smokers group were: constipation in 65% nausea in 60%, vomiting in 20%, dry mouth in 20%, reflux in 7%, dyspepsia in 7%, anorexia in 6%, abdominal pain in 6%. The gastrointestinal side effects were often moderate in the two groups; we rotated morphine in just two patients in the group of non-smoker patients as a result of vomiting. Overall, gastrointestinal side effects of morphine in non-smokers were statistically higher than in smokers (77% vs. 27%, p=0.001). 60% of non-smokers had nausea versus 18% in smokers (p=0.001). 20% of non-smokers had vomiting versus 0% in smokers (p=0.003). 65% of non-smokers had constipation versus 20% in smokers (p=0.005). Although other gastrointestinal side effects were higher in non-smoking patients compared to smoker patients, they did not reach statistical significance. There was a significant difference in terms of gastrointestinal side effects between smoker and non-smoker patients. Higher levels of morphine-induced gastrointestinal adverse effects were observed in non-smoking patients. Specifically, non-smokers reported more nausea, vomiting, and constipation than smokers.