Efficacy and Safety of 1-L Polyethylene Glycol With Low Ascorbic Acid for Bowel Preparation: A Randomized Clinical Trial
In brief
Reduced-ascorbic 1-L bowel prep cleans effectively in 93% of patients
In a randomized trial of 242 low-risk adults, the reduced-ascorbic 1-L preparation achieved successful cleansing in 92.7% and met noninferiority criteria versus standard 1-L and 2-L preparations. Other cleansing measures, tolerability and adverse events were similar, with no electrolyte or kidney events observed; whether safety holds in higher-risk patients remains unknown.
- Journal
- Journal of gastroenterology and hepatology (Q1)
- Published
- 30 September 2026
- Study design
- Randomized controlled trial
- Evidence level
- Level 1, High (CEBM 1b)
- Authors
- Ji Eun Baek, Hyo Suk Kim, Sung Hoon Jung, Sang-Bum Kang, Bo-In Lee, Kang-Moon Lee
- PMID
- 42813603
- DOI
- 10.1111/jgh.70781
Why clinicians should know about it
- Picked for Gastroenterology (top studies of the week, 4 October 2026): Noninferior 1‑L PEG regimen, high ADR, tolerability
Abstract
BACKGROUND AND AIMS: Ultra-low-volume polyethylene glycol (PEG) with ascorbic acid (Asc) improves tolerability, but Asc-related gastrointestinal and metabolic adverse events remain a concern. Whether reducing the Asc dose preserves cleansing efficacy without compromising safety is unclear. We compared a modified 1-L PEG regimen with reduced Asc (1-L PEG + low Asc) with standard 1-L PEG + Asc and 2-L PEG + Asc formulations. METHODS: In this multicenter, randomized, investigator-blinded, three-arm noninferiority trial across five hospitals, low-risk adults undergoing colonoscopy were allocated (1:1:1) to 1-L PEG + low Asc, 1-L PEG + Asc, or 2-L PEG + Asc. The primary endpoint was successful bowel cleansing by the Harefield Cleansing Scale (HCS). Secondary endpoints included Boston Bowel Preparation Scale (BBPS), endoscopic outcomes, gastric residual volume quantified by esophagogastroduodenoscopy, patient-reported tolerability, and adverse events. RESULTS: Among 242 per-protocol participants, HCS-defined successful cleansing was achieved in 92.7% with 1-L PEG + low Asc, 100.0% with 1-L PEG + Asc, and 98.7% with 2-L PEG + Asc (p = 0.01). The low-Asc regimen met noninferiority criteria versus both comparators (risk difference vs. 1-L PEG + Asc, -7.3%; 97.5% CI, -13.0 to -1.6). BBPS-defined success, adenoma detection rate (31.7%, 18.1%, and 20.8%), gastric fluid volume (27.4, 28.2, and 25.2 mL), and willingness to repeat the regimen (78.0%, 73.5%, and 71.4%) were similar across groups. Adverse-event rates were comparable, with no electrolyte disturbances or renal events observed. CONCLUSIONS: A modified 1-L PEG regimen with reduced Asc provides bowel cleansing efficacy noninferior to both standard 1-L and 2-L PEG + Asc preparations, with comparable tolerability and safety.
Abstract as published, via PubMed.
For healthcare professionals. The summary is generated by AI from the published abstract, and the evidence level is assigned automatically from the study design on the Oxford CEBM hierarchy. Neither is medical advice. Read the full paper before changing practice.