Comparative evaluation of the effects of Polyethylene Glycol, Monobasic Sodium Phosphate, and Sennoside A-B Calcium solutions used for pre-colonoscopy bowel preparation on colonic mucosa, serum TAS/TOS levels, and serum IL-6 levels

Objective: Colonoscopy is an interventional procedure for the diagnosis, follow-up and treatment process of many bowel diseases especially the colorectal cancer. In order to ensure a good mucosal visualization during the procedure, bowel preparations is needed. In the past times, bowel cleansing was done using a strict liquid diet and drinking lots of tap water. But with the usage of new solutions, the colonoscopy procedure has become easier and more effective. Although there are numerous studies in the literature about these solutions' effectiveness, cleaning ability, effects on serum electrolyte levels, and clinical side effects, it has not seen any research about their effect on oxidative stress and inflammation in the serum and colonic tissue. In this study, we aimed to investigate the effects of three common bowel preparation solutions—Polyethylene Glycol 3350 (PEG), Monobasic Sodium Phosphate (NaP), and Sennoside A-B Calcium—on oxidative stress and pro-inflammatory cytokine levels in serum and colonic mucosa. Blood samples were taken from the patients before and after using the solutions and the sigmoid colon mucosal sample was taken during the colonoscopy from each patient. Both oxidative stress markers —Total Oxidant Status (TOS), Total Antioxidant Status (TAS) — and pro-inflammatory cytokine Interleukin-6 (IL-6) were measured from the serum and colonic mucosal TOS, TAS levels are measured. The Oxidative Stress Index (OSI) was calculated. Because the DNA damage induced by oxidative stress may have a precancerous effect in the long term, interest in the relationship between the oxidative stress and bowel diseases—especially cancers and inflammatory bowel disease—has increased in the literature nowadays. So, it is now important to evaluate the safetiness of bowel cleansing solutions in terms of oxidative stress and inflammation. Materials and Methods:A total of 76 patients who were planned for colonoscopy were randomly divided into three groups, and each group used a different bowel cleansing solution. Two cubital venous blood samples were taken from each patient before and after using the solution. Also, a biopsy sample was taken from the sigmoid colon during the colonoscopy. In the serum, White Blood Cell (WBC) count, C-Reactive Protein (CRP), TAS, TOS, OSI, and IL-6 levels were measured. In the tissue, TAS, TOS, and OSI were measured. The results were calculated wtih using ELISA and spectrophotometric methods, and the data were analyzed with SPSS software program. Changes in serum samples before and after were shown as "Δ" (delta) marker. Results:There was no statistically significant difference in IL-6 (Δ), TAS (Δ), TOS (Δ), and OSI (Δ) levels between the three groups (p > 0. 05). In the colon tissue samples, a significant difference was found in TOS levels between the solutions (p = 0. 043), but subgroup analyses did not reach statistical significance (p > 0. 05). The closest difference to significance was between Sennoside A-B Calcium and Monobasic Sodium Phosphate (p = 0. 054), with NaP showing a higher level of tissue oxidation. There was no correlation between classical inflammation markers (CRP, WBC, IL-6) and oxidative stress markers (p > 0. 05). Also, Boston Bowel Preparation Scores (BBPS) and ASA (American Society of Anesthesiologists) scores of the patients were calculated. No relationship or impact was found between these scores and oxidative stress parameters (p > 0. 05). The BBPS scores for PEG, NaP, Sennoside A-B Calcium were respectively 6. 1±1. 63, 6, 04 ± 1, 39, 6. 17 ±1, 37 (mean ± SD). Conclusion:Based on the results, none of the three bowel preparation solutions had an obvious effect on systemic oxidative stress or pro-inflammatory response in the serum. Although there was a statistically significant difference in tissue TOS values in the colon mucosa, subgroup differences were not significant. The closest significant difference in tissue TOS was found between NaP and Sennoside A-B Calcium, with NaP causing more oxidation. No difference was found in BBPS scores between the three groups. As a conclusion, although the solutions seem to have similar safety profiles for short-term use, the biochemical effects of these preparations should still be considered when choosing a bowel cleansing method.