Intestinal and renal effects of low-volume phosphate and sulfate cathartic solutions designed for cleansing the colon: pathophysiological studies in five normal subjects

Endoscopy in Special Situations in Inflammatory Bowel Disease: Acute Colitis, Pregnancy, and Pediatrics

Endoscopy for a hospitalized patient with acute severe ulcerative colitis should be limited to flexible sigmoidoscopy. If, during pregnancy, inflammatory bowel disease (IBD) is active or if a new diagnosis of IBD is suspected, endoscopy may be needed to guide medical decision-making. The determination to proceed with endoscopy during pregnancy is nuanced and requires the ability to discern appropriate indications, knowledge regarding safety of bowel preparation and anesthesia. Pediatric patients with IBD represent a unique subset of IBD with distinctive diagnostic, therapeutic, and monitoring considerations.

Efficacy, tolerability, and safety of oral sulfate tablet versus 2 L-polyethylene glycol/ascorbate for bowel preparation in older patients: prospective, multicenter, investigator single-blinded, randomized study

BACKGROUND

We compared the efficacy, tolerability, and safety of oral sulfate tablets (OST, which contains simethicone) and 2 L-polyethylene glycol/ascorbate (2 L-PEG/Asc) with a split-dosing regimen in older individuals aged ≥ 70 years who underwent scheduled colonoscopy.

METHODS

This prospective, randomized, investigator-blinded, multicenter study was conducted between June 2022 and October 2023. Participants aged ≥ 70 years were randomized at a ratio of 1:1 to the OST or 2 L-PEG/Asc groups.

RESULTS

In total, 254 patients were evaluated using a modified full analysis set. Successful overall bowel preparation was excellent and similar between the OST and 2 L-PEG/Asc groups for the Boston Bowel Preparation Scale (BBPS) (96.5% vs. 96.6%) and Harefield Cleansing Scale (HCS) (96.5% vs. 97.4%). The overall high-quality preparation rate was higher in the OST group than in the 2 L-PEG/Asc group (BBPS: 55.7% vs. 28.4%, P < 0.001; HCS: 66.1% vs. 38.8%, P < 0.001). The overall adenoma detection rate (54.8% vs. 35.3, P = 0.003) was superior in the OST group compared to the 2 L-PEG/Asc group. Tolerability scores, including overall satisfaction, were generally higher in the OST group than in the 2 L-PEG/Asc group. The incidence of major solicited adverse events was comparable between the two groups (55.7% vs. 68.1, P = 0.051), and there were no clinically significant changes in the serum laboratory profiles on the day of or 7 days after colonoscopy.

CONCLUSIONS

OST is an effective and safe low-volume agent for colonoscopy, with better tolerance than 2 L-PEG/Asc, in older individuals aged ≥ 70 years.

Comparison of a Novel, Flavor-optimized, Polyethylene Glycol and Sulfate Bowel Preparation With Oral Sulfate Solution in Adults Undergoing Colonoscopy

INTRODUCTION

A new bowel preparation for colonoscopy has been developed containing poorly absorbed sulfate salts and polyethylene glycol 3350, which retain water within the intestinal lumen resulting in copious diarrhea, thereby cleansing the bowel. The product was formulated to be safe and effective with a sports drink-like flavor. This study evaluated the new flavored polyethylene glycol and sulfate solution (FPSS) compared with a Food and Drug Administration-approved bowel preparation containing sulfate salts only [oral sulfate solution (OSS)].

METHODS

Five hundred adults were enrolled in this multicenter, noninferiority study. Subjects were assigned FPSS or OSS administered in split-dose regimens (PM/AM). FPSS subjects took 2 L of the flavored osmotic solution (1 L at night and 1 L in the morning). OSS was taken according to its approved labeling. Colonoscopies were graded globally and segmentally by blinded local investigators using a 4-point scale (excellent, good, fair, and poor), with "good" and "excellent" considered successful. Safety was assessed by adverse events (AEs) and laboratory testing.

RESULTS

A high rate of cleansing success was seen with FPSS (94%), which was noninferior to OSS (94%). This conclusion was confirmed by blinded central readers. Segmental success rates were >90% for both preparations, including the right colon. Questionnaire ratings indicated the FPSS experience was preferred over OSS with 87% of FPSS subjects noting their preparation was "tolerable" to "very easy" to consume versus 74% for OSS. The majority of FPSS subjects agreed their preparation tasted like a sports drink. Gastrointestinal symptoms were the most common AEs. There was no difference between preparations for any AE and no clinically significant differences in laboratory parameters.

CONCLUSIONS

The new sports drink-like flavored preparation achieved a high level of cleansing in the study, demonstrating noninferiority to OSS. FPSS was well-tolerated with low rates of expected gastrointestinal symptoms. The optimized flavor of FPSS resulted in significantly better acceptance ratings.

Low-dose of magnesium sulfate solution was not inferior to standard regime of polyethylene glycol for bowel preparation in elderly patients: a randomized, controlled study

BACKGROUND

Large polyethylene glycol (PEG) is a standard regimen for bowel preparation. However, elderly patients suffered from adverse events. This study was to compare the efficacy and safety of oral magnesium sulfate solution (MSS) vs standard PEG in elderly patients undergoing colonoscopy.

METHODS

Elderly patients aged 60-90 years, from two endoscopic centers, were enrolled in China. Patients were randomized to take a low dose of MSS or a standard PEG regime in a split-dose regime. The primary endpoint was the proportion of patients with adequate bowel preparation, which was defined as the total Boston Bowel Preparation Scale (BBPS) ≥6 and each segmental BBPS was ≥2. Secondary outcomes included adenoma detection rate (ADR), safety, adverse events, cecal intubation rate, willingness to repeat BP, and so on.

RESULTS

1174 elderly patients were randomly allocated to the MSS group (n = 588) or the standard group (n = 586). Adequate BP was achieved in 94.0% of patients in the MSS group and 92.5% in the control (p = .287). ADR was also comparable between the two groups (43.0% and 39.9%, p = .282). Compared with the standard group, MSS group reported less abdominal discomfort (1.7% vs 6.0%), less nausea (13.6% vs 21.0%) and vomiting (1.2% vs 4.2%). The change in serum potassium levels after preparation in the standard group was significantly lower than that in the MSS group (-0.19 ± 0.08 vs -0.41 ± 0.11, p = .037).

CONCLUSIONS

Low dose of MSS was not inferior to the standard PEG regime in terms of bowel preparation quality for elderly patients. Low-dose MSS offered fewer adverse events and better tolerability. It is a preferable choice for the elderly to undergo bowel preparation for colonoscopy.

CLINICAL TRIAL REGISTRATION NUMBER

NCT04948567.

Efficacy of ultra-low volume (≤1 L) bowel preparation fluids: Systematic review and meta-analysis

BACKGROUND AND AIMS

High-quality bowel preparation is paramount for the diagnostic accuracy and safety of colonoscopy; however, it is often difficult for patients to adhere to high-volume laxatives, which may contribute to poor bowel preparation. This review aims to assess the efficacy of bowel preparation fluids of 1 L or less (≤1 L).

METHODS

We performed a systematic review including all relevant randomized controlled trials on ultra-low volume (≤1 L) bowel preparation fluids for colonoscopy published since 2015. Primary endpoint was the percentage of adequately prepared patients. Secondary endpoints included adenoma detection rate (ADR) and safety.

RESULTS

Bowel preparation with sodium picosulfate/magnesium citrate (SPMC; 19 trials, n = 10,287), 1L-polyethylene glycol with ascorbate (PEGA; 10 trials, n = 1717), sodium phosphate (NaP; 2 trials, n = 621), and oral sulfate solution (OSS; 3 trials, n = 597) was adequate in 75.2%, 82.9%, 81.9%, and 92.1%, respectively, of patients; however, heterogeneity between studies was considerable (I² range: 86-98%). Pooled ADRs were 31.1% with SPMC, 32.3% with 1L-PEGA, 30.4% with NaP, and 40.9% with OSS. Temporary electrolyte changes were seen with all ultra-low volume bowel preparation fluid solutions but without sustained effects in most patients.

CONCLUSION

Ultra-low volume bowel preparation fluids do not always meet the 90% quality standard for adequate bowel preparation as defined by current guidelines. Nonetheless, they may be considered in patients intolerant for higher-volume laxatives and without risk factors for inadequate bowel preparation or dehydration-related complications.

Endoscopy in Pregnancy: A Systematic Review

Background Fetomaternal outcomes are of primary concern for gastrointestinal (GI) endoscopy in pregnancy. We aimed to systematically review the safety and utility of endoscopic procedures in pregnancy.

Methods A systematic literature search was performed using PubMed. All original research articles with sample size > 10 involving endoscopy in pregnancy were included for the review along with case report/series describing novel/rare techniques from 1948 to July 2021.

Results After screening 12,197 references, 216 citations were found and finally 66 references were included. Esophagogastroduodenoscopy had favorable fetal outcome (>95%) based on two large retrospective studies and a review of case reports. Sclerotherapy and band ligation of varices were safe according to case series. A large nationwide cohort study established safety of endotherapy for nonvariceal bleed. Botulinum toxin and pneumatic dilation in achalasia are only supported by case reports. Percutaneous endoscopic gastrostomy can be useful to support nutrition based on case reports. A retrospective case–control and cohort study with systemic review justified flexible sigmoidoscopy if strongly indicated. Low birth weight was more common when sigmoidoscopy was done in inflammatory bowel disease based on a prospective study. Colonoscopy was considered safe in second trimester based on a case–control study whereas it can be performed otherwise only in presence of strong indication like malignancy. Capsule endoscopy is promising and can be useful in acute small bowel bleeding although risk of capsule retention is unknown. There are no reports of enteroscopy in pregnancy. Twelve retrospective studies and one prospective study showed high success rate of therapeutic endoscopic retrograde cholangiopancreatography (ERCP) (> 90%) in all trimesters and can be performed if strongly indicated. Pregnancy was an independent risk factor for post-ERCP pancreatitis in a large nationwide case–control study. Radiation-free ERCP with wire-guided bile observation, stent-guided or precut sphincterotomy, endoscopic ultrasound (EUS) guidance, and spyscopy have been described. Safety of EUS is limited to case series and can be used in intermediate probability of choledocholithiasis to guide ERCP and endoscopic cystogastrostomy.

Conclusion This review concludes that GI endoscopy during pregnancy can be done effectively if strongly indicated with good fetomaternal outcomes. Precautions are advocated during procedures where radiation exposure is expected.

Comparison Between an Oral Sulfate Solution and a 2 L of Polyethylene Glycol/Ascorbic Acid as a Split Dose Bowel Preparation for Colonoscopy

BACKGROUND/AIMS

This study aimed to compare the efficacy and tolerability of an oral sulfate solution (OSS) versus 2 L of polyethylene glycol/ascorbic acid (2L-PEG/Asc) for bowel cleansing before colonoscopy.

METHODS

A prospective, single-center, single-blinded, noninferiority, randomized, controlled trial was performed. The primary outcome was the rate of successful bowel cleansing, evaluated using the Boston Bowel Preparation Scale (BBPS). Secondary outcomes were examination time, polyp, and adenoma detection rate (PDR and ADR), tolerability, and safety. Ease of use, palatability, intention to reuse, and satisfaction were evaluated using a questionnaire.

RESULTS

A total of 187 participants were randomized to receive either OSS (n=93) or 2L-PEG/Asc (n=94). Successful bowel cleansing was achieved in 86.0% (80/93) of the OSS group, which was noninferior to the 2L-PEG/Asc group (88.3%, 83/94), with a difference of -2.3% by ITT analysis [95% confidence interval (CI) -12.0 to +7.4]. The withdrawal time of the OSS group was significantly shorter than that of the 2L-PEG/Asc group (11.8±5.2 vs. 14.3±8.5; P=0.016). Ease of use, palatability, intention to reuse, and satisfaction were similar between the 2 groups. Adverse events were also similar between the 2 groups. Mucosal erythema (4.3%) and aphthous lesions (2.1%) were found only in the 2L-PEG/Asc group.

CONCLUSIONS

OSS was as effective as 2L-PEG/Asc for successful bowel cleansing and had acceptable tolerability. OSS is a promising and safe low-volume preparation alternative for colonoscopy. (Clinical trial registration number: NCT02761213.).

Safety and Efficacy of Low-Volume Preparation in the Elderly: Oral Sulfate Solution on the Day before and Split-Dose Regimens (SEE SAFE) Study

Background/Aims

The use of a low-volume bowel cleansing agent is associated with a greater willingness to undergo repeat colonoscopy. Oral sulfate solution (OSS) is a recently approved low-volume agent; however, its efficacy and safety in the elderly population remain unclear. We aimed to evaluate the efficacy, safety, and acceptability of the OSS preparation, in comparison to those of a standard polyethylene glycol (PEG; 4 L) preparation, in elderly patients.

Methods

A multicenter, randomized, investigator-blinded study was conducted. Participants were randomized to receive OSS or 4-L PEG with a split-dose regimen. Bowel cleansing efficacy was assessed using the Boston Bowel Preparation Scale (BBPS). Acceptance, satisfaction, and preparation-related symptoms were recorded. Additionally, blood parameters were analyzed for electrolyte abnormalities and nephrotoxicity.

Results

A total of 193 patients were analyzed. No group differences in overall bowel cleansing efficacy were observed, with “adequate” preparations achieved in 95.9% (93/97) and 94.8% (91/96) of patients in the OSS and 4L PEG groups, respectively (p=0.747). However, mean BBPS scores for the entire (p=0.010) and right colon (p=0.001) were significantly higher in the OSS group than in the 4-L PEG group. The severity of clinical adverse events and frequency of acute kidney injury were similarly low, and no clinically meaningful electrolyte changes were identified. Self-reported scores regarding amount (p<0.001) and feeling (p=0.007), as well as overall satisfaction (p=0.001) and willingness to repeat the preparation (92.8% vs 67.7%, p<0.001), were significantly better in the OSS group than in the 4-L PEG group.

Conclusions

In elderly individuals, OSS with a split-dose regimen has greater acceptability and comparable efficacy in bowel cleansing compared to 4-L PEG. (Clinical trials registration number: NCT03112967)

Novel 1 L polyethylene glycol-based bowel preparation (NER1006): proof of concept assessment versus standard 2 L polyethylene glycol with ascorbate - a randomized, parallel group, phase 2, colonoscopist-blinded trial

Background

Colonoscopy requires colon cleansing. For this, many polyethylene glycol (PEG)-based preparations still require a high preparation-volume intake. Using an increased osmotic load with ascorbate (Asc), five new low-volume PEG-based bowel preparations (LVPEG) were tested for clinical proof of concept.

Methods

This two-part, open-label study examined preparation-volumes of 1–1.25 L and total required fluid volumes of 2–3 L. Part 1, in healthy volunteers, used mean cumulative 24-h stool weight (target > 2750 g) to identify a lead candidate. Part 2 was endoscopist-blinded: patients undergoing screening colonoscopy were randomized before treatment with the selected lead, one of two variants of it, or the control 2 L PEG + Asc. Two primary endpoints were used for proof of concept demonstration: mean 24-h stool weight and bowel cleansing success (Harefield Cleansing Scale).

Results

A total of 120 subjects (30 per group) were enrolled/randomized 1:1:1:1 (max 40:60 gender ratio) per completed Part. In Part 1, LVPEG-3 achieved the largest mean stool weight (3399 g: P < 0.0001 vs target) and was selected for Part 2. In Part 2, stool weights exceeded the target, notably for LVPEG-4 (3215 g: P < 0.001), which achieved 100% cleansing success after a total required fluid intake of 2 L. The control achieved 90% cleansing success. Adverse events were few, gastrointestinal in nature and similar between groups.

Conclusions

LVPEG-4 achieved a clinically useful combination of cleansing, safety/tolerability and low consumption volume: 1 L preparation + 1 L required additional fluid. Named NER1006, LVPEG-4 demonstrated clinical proof of concept and warrants further investigation.

Trial registration

October 2012.

Identifier: NCT01714466. EudraCT: 2012–003052-37

The trial was prospectively registered.

Electronic supplementary material

The online version of this article (10.1186/s12876-019-0988-y) contains supplementary material, which is available to authorized users.

A comparative review of use of sulphate and phosphate salts for colonoscopy preparations and their potential for nephrotoxicity

Background and study aims  Colonoscopy is a widely used diagnostic procedure which requires prior cleansing of the bowel. Many different bowel cleansing preparations have been developed, all of which have specific advantages and disadvantages. This review compares two low-volume high-osmolarity bowel cleansing preparations, oral phosphate salts and oral sulphate salts, with a particular focus on risk of nephrotoxicity. Patients and methods  An electronic search of the Medline database was performed using the search terms "(phosphates OR sulfates) AND cathartics [MeSH Term] AND kidney" restricted to humans with a cut-off date of December 31, 2016. Results  Introduction of oral phosphate salts offered the advantage of low intake volume and low risk of bowel irritation compared to previous options. However, phosphate salts have been associated with renal toxicity (acute phosphate nephropathy [APN]), thought to arise due to perturbations of calcium and phosphate homeostasis as a consequence of increases in serum phosphate. This results in high concentrations of calcium phosphate in the distal tubule and collecting ducts of the kidney, where it may precipitate. Although APN is rare, it may lead to permanent kidney damage. For this reason, phosphate salts are contraindicated in vulnerable patient groups. As an alternative to phosphate salts, oral sulphate salts have recently been introduced. Because sulphate absorption from the intestinal tract is saturable, serum sulphate concentrations increase only minimally after ingestion. Furthermore, excretion of sulphate in the kidney is not accompanied by calcium excretion and urine calcium levels are unchanged. For these theoretical reasons, use of sulphate salts as bowel cleansing solutions is not expected to lead to calcium precipitation in the nephron. Conclusions  Oral phosphate salts are no longer recommended for routine use as bowel cleansing preparations as they carry significant risk of kidney damage and a safer alternative is available in the form of oral sulphate solutions. To date, use of sulphate salts has not been associated with elevations in serum creatinine or other markers of renal impairment, nor with clinical manifestations of kidney injury. Nonetheless, experience with sulphate salts in everyday practice is limited and physicians should be vigilant in detecting potential safety issues.

Comparative Evaluation of the Efficacy of Polyethylene Glycol With Ascorbic Acid and an Oral Sulfate Solution in a Split Method for Bowel Preparation: A Randomized, Multicenter Phase III Clinical Trial

BACKGROUND

An adequate level of bowel preparation before colonoscopy is important. The ideal agent for bowel preparation should be effective and tolerable.

OBJECTIVE

The purpose of this study was to compare the clinical efficacy and tolerability of polyethylene glycol with ascorbic acid and oral sulfate solution in a split method for bowel preparation.

DESIGN

This was a prospective, multicenter, randomized controlled clinical trial.

SETTINGS

Outpatients at the specialized clinics were included.

PATIENTS

A total of 186 subjects were randomly assigned. After exclusions, 84 subjects in the polyethylene glycol with ascorbic acid group and 83 subjects in the oral sulfate solution group completed the study and were analyzed.

INTERVENTIONS

Polyethylene glycol with ascorbic acid or oral sulfate solution in a split method was the included intervention.

MAIN OUTCOME MEASURES

The primary end point was the rate of successful bowel preparation, which was defined as being excellent or good on the Aronchick scale. Tolerability and adverse events were also measured.

RESULTS

Success of bowel preparation was not different between 2 groups (91.7% vs 96.4%; p = 0.20), and the rate of adverse GI events (abdominal distension, pain, nausea, vomiting, or abdominal discomfort) was not significantly different between the 2 groups. In contrast, the mean intensity of vomiting was higher in the oral sulfate solution group than in the polyethylene glycol with ascorbic acid group (1.6 ± 0.9 vs 1.9 ± 1.1; p = 0.02).

LIMITATIONS

All of the colonoscopies were performed in the morning, and the subjects were offered enhanced instructions for bowel preparation. In addition, the results of tolerability and adverse effect may have a type II error, because the number of cases was calculated for confirming the efficacy of bowel preparation.

CONCLUSIONS

Oral sulfate solution is effective at colonoscopy cleansing and has acceptable tolerability when it is compared with polyethylene glycol with ascorbic acid. The taste and flavor of oral sulfate solution still need to be improved to enhance tolerability.

Bowel cleansing before colonoscopy: Balancing efficacy, safety, cost and patient tolerance

Effective colorectal cancer screening relies on reliable colonoscopy findings which are themselves dependent on adequate bowel cleansing. Research has consistently demonstrated that inadequate bowel preparation adversely affects the adenoma detection rate and leads gastroenterologists to recommend earlier follow up than is consistent with published guidelines. Poor preparation affects as many as 30% of colonoscopies and contributes to an increased cost of colonoscopies. Patient tolerability is strongly affected by the preparation chosen and manner in which it is administered. Poor tolerability is, in turn, associated with lower quality bowel preparations. Recently, several new developments in both agents being used for bowel preparation and in the timing of administration have brought endoscopists closer to achieving the goal of effective, reliable, safe, and tolerable regimens. Historically, large volume preparations given in a single dose were administered to patients in order to achieve adequate bowel cleansing. These were poorly tolerated, and the unpleasant taste of and significant side effects produced by these large volume regimens contributed significantly to patients’ inability to reliably complete the preparation and to a reluctance to repeat the procedure. Smaller volumes, including preparations that are administered as tablets to be consumed with water, given as split doses have significantly improved both the patient experience and efficacy, and an appreciation of the importance of the preparation to colonoscopy interval have produced additional cleansing.

A Comparative Study of Treatment-Emergent Adverse Events Following Use of Common Bowel Preparations Among a Colonoscopy Screening Population: Results from a Post-Marketing Observational Study

BACKGROUND

Colonoscopy may be one of the most frequent elective procedures in older adults and is associated with a low occurrence of complications. However, reduction of risks attributable to the bowel preparation may be achieved with the use of effective and safer products.

AIM

The aim of this study was to examine the incidence of treatment-emergent adverse events (TEAEs) associated with SUPREP(®) [oral sulfate solution (OSS)] and other common prescription bowel preparations (non-OSS).

METHODS

This real-world, observational study used de-identified health insurance claims and laboratory results to identify TEAEs in the 3 months following screening colonoscopy in adults with a prescription for a bowel preparation in the prior 60 days. The unadjusted and adjusted (controlling for patient risk factors) cumulative incidences of TEAEs were estimated using Kaplan-Meier and Poisson regression, respectively.

RESULTS

Among patients ≥45 years, the overall cumulative incidence was significantly lower (p < 0.001) in the OSS cohort than in the non-OSS cohort (unadjusted: 2.31 vs. 2.89 %; adjusted: 1.61 vs. 1.95 %), with significantly lower acute cardiac conditions (1.56 vs. 1.90 %; p < 0.001), renal failure/other serious renal diseases (OSS: 0.21 %, non-OSS: 0.32 %; p < 0.001), and serum electrolyte abnormalities (OSS: 0.39 %, non-OSS: 0.49 %; p = 0.017). There were no significant differences between cohorts in death, seizure disorders, aggravation of gout, and ischemic colitis. Results were similar in the adjusted cumulative incidences.

CONCLUSIONS

In actual use, the overall cumulative incidence of TEAEs was significantly lower in the OSS cohort, demonstrating that OSS is as safe as, or possibly safer than, non-OSS prescription bowel preparations.

Modified dachengqi tang improves decreased gastrointestinal motility in postoperative esophageal cancer patients

OBJECTIVE

To investigate the clinical effects of modified dachengqi tang (DCQT) on promoting gastrointestinal motility in post-operative esophageal cancer patients.

METHODS

Sixty postoperative esophageal cancer patients were enrolled and randomly assigned to the modified treatment group or the control group (30 patients in each group). Patients in the treatment group were given DCQT made from decocted herbs and administered via nasojejunal tube at a dosage of 150 mL. Gastrointestinal motility was assessed by recording time for recovery of bowel sounds, flatus, defecation, and the total amount of gastric drainage during the first three postoperative days. Plasma motilin (MTL) and vasoactive intestinal peptide (VIP) were measured one hour before and three days after surgery.

RESULTS

Compared with the control group, the times to first bowel sound, flatus, and defecation were significantly shorter and there was less gastric drainage in the treatment group (P < 0.01, P < 0.01, P < 0.01, and P < 0.05, respectively). In the treatment group, postoperative plasma MTL was significantly higher (P < 0.01) and VIP was significantly lower than those in the control group (P < 0.05). There was no difference found in either MTL or VIP from before to after operation in the treatment group (P > 0.05). MTL was significantly lower and VIP was higher postoperatively in the control group, compared to before surgery (P < 0.01).

CONCLUSION

Modified DCQT effectively improved decreased gastrointestinal motility in postoperative esophageal cancer patients by increasing MTL and reducing VIP.

Polyethylene glycol plus an oral sulfate solution as a bowel cleansing regimen for colon capsule endoscopy: a prospective, single-arm study in healthy volunteers

OBJECTIVES

As with colonoscopy, adequate bowel cleansing is essential prior to colon capsule endoscopy (CCE). Because CCE requires that the capsule traverse the entire gastrointestinal tract during the examination, laxative 'boosters' are used. The objective of this prospective, single-center, single-arm study was to evaluate the safety of a bowel preparation consisting of polyethylene glycol (PEG) plus an oral sulfate solution.

METHODS

Subjects were healthy volunteers aged 50-75 years old with normal baseline serum chemistry. The bowel preparation consisted of 4 Senna tablets, 4 liters of PEG (split dose), 10 mg metoclopramide, 2 oral sulfate solution boosters (6 oz. and 3 oz.), and 10 mg bisacodyl. Serum chemistry was performed at baseline, following PEG intake, 24 hours after bisacodyl administration, and at 7 days post procedure (in subjects with abnormal 24 hour results). The primary endpoints were the percentage of subjects with a clinically significant change in serum chemistry at the last test and the adverse event (AE) rate.

RESULTS

A total of 25 subjects were enrolled. The serum chemistry was normal in all subjects at the final evaluation. One subject showed a slight elevation in creatinine (1.08 mg/dl 7 days post procedure from 0.84 mg/dl at baseline), deemed not clinically significant. Another subject had a transient elevation in serum creatinine (from 1.01 mg/dl at baseline to 1.45 mg/dl at 24 hours after the bowel preparation); values returned to near baseline at 7 days post procedure (1.06 mg/dl). There were no serious AEs, three moderate AEs related to the bowel preparation (nausea, headache, elevated creatinine) and two mild unrelated AEs (chills, abdominal cramping).

CONCLUSIONS

A bowel cleansing regimen of PEG plus an oral sulfate solution can be used in healthy volunteers. These data provide support for the continued study of this regimen in future CCE clinical trials and in medical practice.

Evaluation of intestinal phosphate binding to improve the safety profile of oral sodium phosphate bowel cleansing

Prior to colonoscopy, bowel cleansing is performed for which frequently oral sodium phosphate (OSP) is used. OSP results in significant hyperphosphatemia and cases of acute kidney injury (AKI) referred to as acute phosphate nephropathy (APN; characterized by nephrocalcinosis) are reported after OSP use, which led to a US-FDA warning. To improve the safety profile of OSP, it was evaluated whether the side-effects of OSP could be prevented with intestinal phosphate binders. Hereto a Wistar rat model of APN was developed. OSP administration (2 times 1.2 g phosphate by gavage) with a 12h time interval induced bowel cleansing (severe diarrhea) and significant hyperphosphatemia (21.79 ± 5.07 mg/dl 6h after the second OSP dose versus 8.44 ± 0.97 mg/dl at baseline). Concomitantly, serum PTH levels increased fivefold and FGF-23 levels showed a threefold increase, while serum calcium levels significantly decreased from 11.29 ± 0.53 mg/dl at baseline to 8.68 ± 0.79 mg/dl after OSP. OSP administration induced weaker NaPi-2a staining along the apical proximal tubular membrane. APN was induced: serum creatinine increased (1.5 times baseline) and nephrocalcinosis developed (increased renal calcium and phosphate content and calcium phosphate deposits on Von Kossa stained kidney sections). Intestinal phosphate binding (lanthanum carbonate or aluminum hydroxide) was not able to attenuate the OSP induced side-effects. In conclusion, a clinically relevant rat model of APN was developed. Animals showed increased serum phosphate levels similar to those reported in humans and developed APN. No evidence was found for an improved safety profile of OSP by using intestinal phosphate binders.

[Bowel preparation for colonoscopy. Any significant progress on the horizon?]

Colonoscopy is the method of choice for colorectal cancer screening. To be effective, screening colonoscopy must have high quality standards. The key element is the quality of the preparation. However, up to 20% of patients are inadequately prepared and, at present, anterograde washing is the least tolerated part of the procedure. In the choice of preparation, safety is a prerequisite and efficacy is a priority. Tolerance is a secondary but nevertheless influential factor in the quality of preparation and has consequently been the primary focus of many recent studies. In the last few years, a rapidly increasing number of studies have evaluated new drugs, dosages and adjuvant therapies to improve efficacy and tolerability. These studies have collaterally shown that inadequate preparation and lack of adherence to the prescribed regimen can be partially predicted, making it essential to identify this patient subgroup and invest the necessary effort in their instruction. New individualized and flexible approaches are expected for the different clinical scenarios. The search for the ideal colonoscopy preparation, which would be tolerable, safe and above all effective, remains open.

Sodium phosphate does not increase risk for acute kidney injury after routine colonoscopy, compared with polyethylene glycol

BACKGROUND & AIMS

Oral sodium phosphate (OSP) is a common bowel purgative administered before colonoscopy; the Food and Drug Administration has warned against its use because of concerns about acute kidney injury (AKI) from the absorbed phosphate and dystrophic calcification. However, it is not clear if OSP is associated with AKI in the general population or in high-risk subgroups undergoing colonoscopy. We estimated the risk of AKI among patients undergoing a screening colonoscopy using OSP vs polyethylene glycol (PEG) for bowel cleansing in a large, US-based claims database.

METHODS

We used an insurance database to identify a cohort of patients ages 50 to 75 years who underwent screening colonoscopies as outpatients from January 2000 through November 2008 (before the Food and Drug Administration warning), receiving OSP (n = 121,266) or PEG (n = 429,430) within 30 days beforehand, without prior use of either drug. We collected data from patients for 6 months afterward to identify those who developed AKI or renal failure, or received dialysis. Adjusted and propensity score-matched hazard ratios (HR) and 95% confidence intervals (CI) were estimated using Cox proportional hazards models. We investigated the effects in subgroups with higher AKI risk (patients with chronic kidney disease, kidney stones, hypertension, or diabetes, or using antihypertensive or nonsteroidal anti-inflammatory drugs).

RESULTS

AKI occurred in 0.2% of OSP users and in 0.3% of PEG users (adjusted HR, 0.86; 95% CI, 0.75-0.99). OSP users matched well with PEG users, producing similar estimates (HR, 0.85; 95% CI, 0.72-1.01). We did not observe a consistent increase in the risk of AKI or other outcomes in any subgroups analyzed.

CONCLUSIONS

In a large database analysis, we did not associate administration of OSP before colonoscopy with increased risk of postprocedure AKI, even in high-risk clinical subgroups.

Colon cleansing for colonoscopy 2013: current status

Colonoscopy requires adequate bowel cleansing to be safe and effective. There are a variety of options available. This review will focus on highlighting new products, administration techniques emphasizing the value of split-dose and same-day regimens, safety, and options for inadequate cleansing.

The modern bowel preparation in colonoscopy

Adequate bowel preparation is essential for optimal colonoscopy. Suboptimal bowel preparation occurs in 25% to 40% of cases and is associated with canceled procedures, prolonged procedure time, incomplete examination, increased cost, and missed pathology. There are several effective formulations for colon cleansing with a good safety profile. Split dosing should be implemented whenever possible in an effort to enhance tolerance and adherence, and improve mucosal visibility and overall quality of the examination. In this review, modern bowel preparations are discussed including their mechanism of action, mode of use, safety, and how to optimize outcomes.

A pilot study using reduced-volume oral sulfate solution as a preparation for colonoscopy among a Japanese population

BACKGROUND

This pilot study sought to investigate the performance and safety of a reduced-volume oral sulfate solution for use as a bowel-cleansing regimen prior to colonoscopy in a Japanese population.

METHODS

Subjects followed a prescribed split-dose regimen in which the first portion was taken on the evening before colonoscopy and the second portion on the morning of the procedure. To determine the performance of this regimen, the quality of colon cleansing was assessed in each case using a validated four-point scale, and elapsed time to complete the preparation was recorded. Side effects and adverse events were investigated by blood sampling and questionnaire.

RESULTS

The successful preparation rate based on the colon-cleansing score was 97 % (30/31). Mean elapsed time to complete the preparation on the day of colonoscopy was 71 min. Serum levels of indirect bilirubin were significantly increased to abnormal levels following the preparation, although these changes were only transient. Preparation-related symptoms of nausea and vomiting were presented in only one case.

CONCLUSIONS

This pilot study showed the oral sulfate solution-based bowel preparation to be safe, easy, and quick to use for Japanese patients. A larger study is necessary to statistically verify these results.

Advances in bowel preparations: new formulation and clinical results

Adequate cleansing is essential for a thorough and accurate examination of the bowel during colonoscopy. Suboptimal preparation can lead to missed diagnoses, increased costs, and safety issues. Favorable bowel preparations are efficacious, safe, and cause as little patient discomfort as possible by limiting fluid volume, intolerance, and inconvenience. Split-dose (2-day) regimens address these concerns and are associated with better cleansing and higher patient satisfaction than with single-dose regimens. Nurses can play a key role in communicating the benefits of various bowel preparation options, including split dosing, to patients.A low-volume oral sulfate solution given as a split-dose regimen has been tested in randomized clinical trials and found to provide similar bowel cleaning to split-dose polyethylene glycol with electrolytes and ascorbic acid (PEG-EA). Superior cleaning was found when compared with single-dose polyethylene glycol with electrolytes (PEG-ELS), particularly in the cecum and ascending colon. With the exception of clinically insignificant changes in electrolytes, tolerability and safety were similar between patients taking oral sulfate solution and patients taking PEG-EA or PEG-ELS. Oral sulfate solution is a safe and effective low-volume bowel preparation for colonoscopy.

Risks versus benefits of gastrointestinal endoscopy during pregnancy

Although gastrointestinal endoscopy is generally safe, its safety must be separately analyzed during pregnancy with regard to fetal safety. Fetal risks from endoscopic medications are minimized by avoiding FDA category D drugs, minimizing endoscopic medications, and anesthesiologist attendance at endoscopy. Esophagogastroduodenoscopy seems to be relatively safe for the fetus and may be performed when strongly indicated during pregnancy. Despite limited clinical data, endoscopic banding of esophageal varices and endoscopic hemostasis of nonvariceal upper gastrointestinal bleeding seems justifiable during pregnancy. Flexible sigmoidoscopy during pregnancy also appears to be relatively safe for the fetus and may be performed when strongly indicated. Colonoscopy may be considered in pregnant patients during the second trimester if there is a strong indication. Data on colonoscopy during the other trimesters are limited. Therapeutic endoscopic retrograde cholangiopancreatography seems to be relatively safe during pregnancy and should be performed for strong indications (for example, complicated choledocholithiasis). Endoscopic safety precautions during pregnancy include the performance of endoscopy in hospital by an expert endoscopist and only when strongly indicated, deferral of endoscopy to the second trimester whenever possible, and obstetric consultation.

Update on preparation for colonoscopy

Colonoscopy requires adequate bowel cleansing to be safe and effective. Current options for preparation include dietary restrictions plus cathartics and purgatives, large-volume gut lavage solutions, and sodium phosphate preparations. Gut lavage with or without a stimulant laxative is safe and effective, and traditionally is taken the evening before the procedure. Sodium phosphate formulations also provide effective cleansing, but fluid and electrolyte disturbances can occur. Recent advances include split administration of gut lavage solutions-ingesting only half of the solution the evening prior to, and the rest the morning of, the procedure. Split administration can yield adequate preparations in inpatients, traditionally a difficult group for proper cleansing. A new oral sulfate solution, when commercially available, should provide safe, effective cleaning with a lower ingested volume. This review discusses the current clinical experience of available preparation options and the efforts to make preparation for colonoscopy more tolerable.

The safety of osmotically acting cathartics in colonic cleansing

Efficient cleansing of the colon before a colonoscopy or a radiological examination is essential. The osmotically acting cathartics (those given the Anatomical Therapeutic Chemical code A06AD) currently used for this purpose comprise products based on three main substances: sodium phosphate, combinations of polyethylene glycol and electrolyte lavage solutions (PEG-ELS), and magnesium citrate. All these preparations give adequate cleansing results and have similar profiles in terms of the frequency and type of mild to moderate adverse effects. However, serious adverse events, such as severe hyperphosphatemia and irreversible kidney damage owing to acute phosphate nephropathy, have been reported after use of sodium-phosphate-based products. The aim of this Review is to provide an update on the potential safety issues related to the use of osmotically acting cathartics, especially disturbances of renal function and water and electrolyte balance. The available evidence indicates that PEG-ELS-based products are the safest option. Magnesium-citrate-based, hypertonic products should be administered with caution to elderly individuals and patients who are prone to develop disturbances in water and electrolyte balance. Sodium-phosphate-based products can occasionally cause irreversible kidney damage and should not be routinely used in bowel-cleansing procedures.

Clinical trial: 2-L polyethylene glycol-based lavage solutions for colonoscopy preparation - a randomized, single-blind study of two formulations

BACKGROUND

The 2-L polyethylene glycol (PEG) lavage solutions provide efficacy similar to that of standard 4-L PEG formulations in spite of the reduced volume. The comparative efficacy and tolerability of two formulations of 2-L PEG solution remain unknown.

AIMS

To assess the efficacy, safety and tolerability of PEG + Bis compared with PEG + Asc, and to study the effect of bowel cleansing quality on adenoma detection rates.

METHODS

Patients were randomized to receive either 2-L PEG with ascorbic acid (PEG + Asc) or 2-L PEG plus bisacodyl 10 mg (PEG + Bis). The primary endpoint was overall colon cleansing score, assessed by blinded investigators using a validated four-point scale. Secondary endpoints included adenoma detection rate, patient tolerability and compliance and adverse events.

RESULTS

Fifty-two patients received PEG + Asc and 55 patients received PEG + Bis. Overall colon cleansing scores (+/-s.d.) were 1.40 +/- 0.69 and 1.75 +/- 0.70 (P < 0.003) in the PEG + Asc and PEG + Bis groups, respectively. Excellent and good ratings were recorded in 69% and 23% receiving PEG + Asc compared to 38% and 51% (P = 0.01) of patients receiving PEG + Bis. More adenomas were detected in colonoscopies performed with PEG + Asc (39%) than in those performed with PEG + Bis (20%) (P = 0.04). Patient tolerability and safety were similar with both preparations.

CONCLUSION

The use of PEG + Asc resulted in better colon cleansing and higher adenoma detection rates compared with PEG + Bis.

A randomized clinical study comparing reduced-volume oral sulfate solution with standard 4-liter sulfate-free electrolyte lavage solution as preparation for colonoscopy

BACKGROUND

Low-volume bowel preparations for colonoscopy improve tolerability.

OBJECTIVE

We compared the efficacy, tolerability, and safety of a new low-volume sulfate solution with a standard 4-L polyethylene glycol electrolyte lavage solution as bowel preparation for colonoscopy.

DESIGN

Multicenter, single-blind, randomized, noninferiority study.

SETTING

Five academic and community endoscopy centers in the United States.

PATIENTS

One hundred thirty-six outpatients undergoing colonoscopy.

INTERVENTIONS

Patients were randomized to receive 4 L sulfate-free electrolyte lavage solution (SF-ELS) given the night before colonoscopy versus 12 oz oral sulfate solution (OSS) given in equally divided doses the evening before and the morning of colonoscopy.

MAIN OUTCOME MEASUREMENTS

Successful (ie, good or excellent) bowel preparation.

RESULTS

Successful bowel preparation was more frequent with OSS than with SF-ELS (98.4% vs 89.6%; P = .04). Excellent preparation also was achieved more frequently with OSS (71.4% vs 34.3%; P < .001). Patients receiving OSS had less residual stool in the cecum and ascending colon and less residual fluid in the cecum and ascending, transverse, and descending colon compared with SF-ELS. The percentage of patients with GI side effects and adverse events was not significantly different between the 2 groups.

LIMITATIONS

The OSS was administered in split doses, whereas the SF-ELS was administered the evening before (which is its FDA-approved regimen).

CONCLUSIONS

Oral sulfate solution is promising as a safe low-volume preparation for colonoscopy. (

CLINICAL TRIAL REGISTRATION NUMBER

NCT00856843.).

A pharmacokinetics evaluation of a new, low-volume, oral sulfate colon cleansing preparation in patients with renal or hepatic impairment and healthy volunteers

The pharmacokinetics (PK) of an oral sulfate solution (OSS) for bowel cleansing preparation was studied. OSS (30 g of sulfate) was split between 2 doses, 12 hours apart. Safety measures included electrocardiography, vital signs, adverse events, hematology, blood chemistry, and urinalysis. Six adult patients with moderate renal disease (MRD), 6 with mild-moderate hepatic disease (M/MHD), and 6 normal healthy volunteers (NHVs) completed the study. Adverse events were mild to moderate in severity and were mainly limited to headache and expected gastrointestinal symptoms. Serum sulfate levels were highly variable at all times, even after adjusting for baseline. Sulfate was higher in MRD in comparison to the other groups. The C(max) and AUC were higher in the patients, but no statistically significant differences emerged. Sulfate levels returned to predose values within 54 hours after dosing. No electrolyte disturbances occurred. Urinary sulfate excretion was approximately 20% of the dose. OSS was well tolerated. The types and severity of adverse events were similar to those seen in large phase III trials. While patients with MRD had elevated sulfate, the levels were less than those in renal failure and did not alter biochemical parameters that are associated with hypersulfatemia.

Editorial: A light breakfast, a jug of salt water, and bowel

Successful colonoscopy is predicated on achieving adequate colon cleansing. An ideal bowel preparation would be low in volume, acceptable to patients, reliable in cleansing efficacy, and safe. The study by Di Palma et al. in this issue shows that a novel, low-volume (960 ml) preparation of mixed sulfate salts can achieve excellent bowel cleansing with acceptable tolerability and minimal electrolyte shifts. A split-dosing strategy, with a proportion of the preparation administered on the day of colonoscopy, achieved a 97.2% preparation success rate vs. 82.4% using a regimen provided entirely the day before colonoscopy. These results were comparable with control groups using a commercially available polyethylene glycol solution. Endoscopists and patients alike should be encouraged by the trend toward lower-dose bowel cleansing regimens that achieve equivalent efficacy compared with large-volume preparations.

Safety of oral sulfates in rats and dogs contrasted with phosphate-induced nephropathy in rats

An oral sulfate salt solution (OSS), under development as a bowel cleansing agent for colonoscopy in humans, is studied in rats and dogs. In rats, amaximumpractical oral OSS dose (5 g/kg/d) is compared with an oral sodium phosphate (OSP) solution, both at about 7 times the clinical dose. OSS induces the intended effects of loose stools and diarrhea. In rats, higher urine sodium and potassium accompany higher clearance rates, considered adaptive to the osmotic load of OSS. OSS for 28 days is well tolerated in rats and dogs. In contrast, OSP causes increased mortality, reduced body weight and food consumption, severe kidney tubular degeneration, and calcium phosphate deposition in rats. These are accompanied by mineralization in the stomach and aorta, along with cardiac and hepatic degeneration and necrosis. The greater safety margin of OSS over OSP at similarmultiples of the clinical dose indicates its suitability for human use.