Pharmacokinetics of oral mannitol for bowel preparation for colonoscopy

Mannitol for bowel preparation: Efficacy and safety results from the SATISFACTION randomised clinical trial

BACKGROUND

Bowel preparation represents a significant issue to high-quality colonoscopy. Oral mannitol requires a single dose, is of low volume, and has a pleasant taste and rapid action.

AIMS

This SATISFACTION study compared single-dose (same day) oral mannitol 100 g/750 mL with standard split-dose PEG-ASC2 L (MoviPrep®).

METHODS

The primary endpoint was the proportion of patients with adequate bowel cleansing. Secondary endpoints included efficacy (adenoma detection rate, caecal intubation rate, time of evacuation), safety (intestinal gases concentration, haemato-chemical parameters, adverse events), and patient satisfaction.

RESULTS

The study included 703 patients (352 treated with mannitol and 351 with PEG-ASC). Mannitol was not inferior to PEG-ASC for the primary endpoint (91.1 % and 95.5 %, respectively; p-value for the non-inferiority =0.0131). There was no significant difference for secondary efficacy endpoints. The acceptability profile was significantly better in the mannitol group for ease of use, taste, and willingness to reuse (p < 0.0001 for all). The concentration of intestinal gases (H2, CH4) was similar between groups and well below those potentially critical.

CONCLUSIONS

The SATISFACTION study indicated that low-volume, single-dose mannitol may satisfy an unmet clinical need since it was more acceptable to the patient and not inferior to the split-dose PEG-ASC for bowel cleansing efficacy.

Toxic Effects of Two Redox States of Thallium on Immortalised Hypothalamic GT1-7 Neuronal Cells

Thallium (Tl), is a highly toxic heavy metal that exists in monovalent (Tl(I)) and trivalent (Tl(III)) ionic states. This study aimed to compare the toxicities of Tl(I) and Tl(III) in a mouse hypothalamic GT1-7 neuronal cell line. Decreased viability and increased cytotoxicity were observed in the GT1-7 cells 16 h after Tl(I) or Tl(III) treatment. Tl(III) was more cytotoxic, than Tl(I), as indicated by extracellular lactate dehydrogenase levels. Both treatments induced caspase 3 activity, DNA fragmentation, malondialdehyde (MDA) production, and superoxide dismutase activity in the cells. MDA production was higher after Tl(III) than after Tl(I) treatment. Moreover, co-treatment with antioxidants, such as mannitol, ascorbic acid, or tocopherol, significantly attenuated the Tl-induced decrease in GT1-7 cell numbers. Therefore, both treatments induced oxidative stress-related apoptosis. Furthermore, Tl(III) reduced the cell viability more subtly than Tl(I) after 1 and 3 h of treatment. This effect was enhanced by co-treatment with maltol or citric acid, which promoted the influx of metallic elements into the cells. Thus, Tl(III) entered GT1-7 cells later than Tl(I) and had a delayed onset of toxicity. However, Tl(III) likely produces more extracellular lipid peroxides, which may explain its stronger cytotoxicity.

Factors influencing the presence of potentially explosive gases during colonoscopy: Results of the SATISFACTION study

This study tested the hypothesis that bowel preparation with mannitol should not affect the colonic concentration of H2 and CH4 . Therefore, the SATISFACTION study, an international, multicenter, randomized, parallel-group phase II-III study investigated this issue. The phase II dose-finding part of the study evaluated H2 , CH4 , and O2 concentrations in 179 patients randomized to treatment with 50 g, 100 g, or 150 g mannitol. Phase III of the study compared the presence of intestinal gases in 680 patients randomized (1:1) to receive mannitol 100 g in single dose or a standard split-dose 2 L polyethylene glycol (PEG)-Asc preparation (2 L PEG-Asc). Phase II results showed that mannitol did not influence the concentration of intestinal gases. During phase III, no patient in either group had H2 or CH4 concentrations above the critical thresholds. In patients with H2 and/or CH4 levels above detectable concentrations, the mean values were below the risk thresholds by at least one order of magnitude. The results also highlighted the effectiveness of standard washing and insufflation maneuvers in removing residual intestinal gases. In conclusion, bowel cleansing with mannitol was safe as the concentrations of H2 and CH4 were the same as those found in patients prepared with 2 L PEG-Asc. In both groups, the concentrations of gases were influenced more by the degree of cleansing achieved and the insufflation and washing maneuvers performed than by the preparation used for bowel cleansing. The trial protocol was registered with ClinicalTrials.gov (https://clinicaltrials.gov/ct2/show/NCT04759885) and with EudraCT (eudract_number: 2019-002856-18).