Methylene blue MMX tablets for chromoendoscopy. Safety tolerability and bioavailability in healthy volunteers

Methylene blue for COVID-19 ARDS: insights from a randomized Clinical Trial

BACKGROUND

Around the world, the COVID-19 pandemic has presented many difficulties, and acute respiratory distress syndrome (ARDS) has become a major worry. The antiviral and anti-inflammatory characteristics of methylene blue (MB) have garnered interest for potential medicinal applications. The object of the current study is to assess the effect of orally administered MB on the treatment of ARDS associated with COVID-19.

METHOD

A randomized clinical study was carried out on 122 hospitalized patients who had ARDS related to COVID-19. Patients who met the eligibility requirements were randomized at random to either the control group (CG) (n = 60) or the intervention group (IG) (n = 62). Standard treatments were administered to both groups, with the addition of oral MB to the IG. Clinical outcomes, including SpO2 levels, CRP levels were assessed on the third and fifth days. Additionally, at the time of discharge, patients' assessments were made in terms of APACHE II scores, SOFA scores, LDH and CRP levels, SpO2, and respiratory rate in comparison to the day prior to the intervention. Patients were followed for mortality outcomes at one month and three months after the intervention.

RESULTS

Significant changes were observed in SpO2 levels over time (P < 0.001) and between groups (P = 0.022), with higher levels in the MB-treated group. The interaction between time and group (P = 0.019) indicated a stronger increase in SpO2 in the IG, with the IG's SpO2 level increasing by 6.42%. Furthermore, CRP levels showed significant changes over time (P < 0.001), but not between groups (P = 0.092). However, the interaction between group and CRP change over time (P = 0.019) suggested a distinct pattern of CRP decrease in the IG. Significant improvement in RR, SpO2, CRP, and APACHE II score were found according to discharge results. However, in terms of SpO2 and the APACHE II score, this improvement was noteworthy for IG. The length of hospitalization and mortality rates at one- and three-month follow-ups did not differ significantly.

CONCLUSION

Oral administration of MB demonstrated positive effects on improving SpO2 levels and reducing inflammatory markers in COVID-19-related ARDS patients. Despite no significant impact on survival rates or hospitalization length, the study supports the potential efficacy of MB as an alternative treatment for COVID-19 ARDS.

TRIAL REGISTRATION

This study was registered with the Iranian Registry of Clinical Trials ( http://www.irct.ir ) under the registration code IRCT20200409047007N2 on 11/29/2021.

In Vitro and Ex Vivo Investigation of the Antibacterial Effects of Methylene Blue against Methicillin-Resistant Staphylococcus aureus

Methylene blue (MB) is a water-soluble dye that has a number of medical applications. Methicillin-resistant Staphylococcus aureus (MRSA) was selected as a subject for research due to the numerous serious clinical diseases it might cause and because there is a significant global resistance challenge. Our main goal was to determine and analyze the antibacterial effects of MB against S. aureus both in vitro and ex vivo to enhance treatment options. A total of 104 MRSA isolates recovered from various clinical specimens were included in this study. Minimum inhibitory concentration (MIC) values of MB against MRSA isolates were determined by the agar dilution method. One randomly selected MRSA isolate and a methicillin-susceptible S. aureus strain (S. aureus ATCC 25923) were employed for further evaluation of the antibacterial effects of MB in in vitro and ex vivo time-kill assays. A disc diffusion method-based MB + antibiotic synergy assay was performed to analyze the subinhibitory effects of MB on ten isolates. MICs of MB against 104 MRSA isolates, detected by the agar dilution method, ranged between 16 and 64 µg/mL. MB concentrations of 4 and 16 µg/mL showed a bactericidal effect at 24 h in the ex vivo time-kill assays and in vitro time-kill assays, respectively. We observed a significant synergy between cefoxitin and methylene blue at a concentration of 1-2 μg/mL in two (20%) test isolates. Employing MB, which has well-defined pharmacokinetics, bioavailability, and safety profiles, for the treatment of MRSA infections and nasal decolonization could be a good strategy.

Effects of methylene blue on microcirculatory alterations following cardiac surgery: A prospective cohort study

BACKGROUND

Methylene blue is used as rescue therapy to treat catecholamine-refractory vasoplegic syndrome after cardiac surgery. However, its microcirculatory effects remain poorly documented.

OBJECTIVE

We aimed to study microcirculatory abnormalities in refractory vasoplegic syndrome following cardiac surgery with cardiopulmonary bypass and assess the effects of methylene blue.

DESIGN

A prospective open-label cohort study.

SETTING

20-Bed ICU of a tertiary care hospital.

PATIENTS

25 Adult patients receiving 1.5 mg kg-1 of methylene blue intravenously for refractory vasoplegic syndrome (defined as norepinephrine requirement more than 0.5 μg kg-1 min-1) to maintain mean arterial pressure (MAP) more than 65 mmHg and cardiac index (CI) more than 2.0 l min-1 m-2.

MAIN OUTCOME MEASURES

Complete haemodynamic set of measurements at baseline and 1 h after the administration of methylene blue. Sublingual microcirculation was investigated by sidestream dark field imaging to obtain microvascular flow index (MFI), total vessel density, perfused vessel density and heterogeneity index. Microvascular reactivity was assessed by peripheral near-infrared (IR) spectroscopy combined with a vascular occlusion test. We also performed a standardised measurement of capillary refill time.

RESULTS

Despite normalised CI (2.6 [2.0 to 3.8] l min-1 m-2) and MAP (66 [55 to 76] mmHg), patients with refractory vasoplegic syndrome showed severe microcirculatory alterations (MFI < 2.6). After methylene blue infusion, MFI significantly increased from 2.0 [0.1 to 2.5] to 2.2 [0.2 to 2.8] (P = 0.008), as did total vessel density from 13.5 [8.3 to 18.5] to 14.9 [10.1 to 14.7] mm mm-2 (P = 0.02) and perfused vessel density density from 7.4 [0.1 to 11.5] to 9.1 [0 to 20.1] mm mm-2 (P = 0.02), but with wide individual variation. Microvascular reactivity assessed by tissue oxygen resaturation speed also increased from 0.5 [0.1 to 1.8] to 0.7 [0.1 to 2.7]% s-1 (P = 0.002). Capillary refill time remained unchanged throughout the study.

CONCLUSION

In refractory vasoplegic syndrome following cardiac surgery, we found microcirculatory alterations despite normalised CI and MAP. The administration of methylene blue could improve microvascular perfusion and reactivity, and partially restore the loss of haemodynamic coherence.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT04250389.

Budding Multi-matrix Technology-a Retrospective Approach, Deep Insights, and Future Perspectives

The human race is consistently striving for achieving good health and eliminate disease-causing factors. For the last few decades, scientists have been endeavoring to invent and innovate technologies that can substitute the conventional dosage forms and enable targeted and prolonged drug release at a particular site. The novel multi-matrix technology is a type of matrix formulation where the formulation is embraced to have a matrix system with multiple number of matrices. The MMX technology embraces with a combination of outer hydrophilic layer and amphiphilic/lipophilic core layer, within which drug is encapsulated followed by enteric coating for extended/targeted release at the required site. In comparison to conventional oral drug delivery systems and other drug delivery systems, multi-matrix (MMX) technology formulations afford many advantages. Additionally, it attributes for targeting strategy aimed at the colon and offers modified prolonged drug release. Thus, it has emerged rapidly as a potential alternative option in targeted oral drug delivery. However, the development of this MMX technology formulations is a exigent task and also has its own set of limitations. Due to its promising advantages and colon targeting strategy over the other colon targeted drug delivery systems, premier global companies are exploiting its potential. This article review deep insights into the formulation procedures, drug delivery mechanism, advantages, limitations, safety and efficacy studies of various marketed drug formulations of MMX technology including regulatory perspectives and future perspectives.

Evaluating the safety of oral methylene blue during swallowing assessment: a systematic review

OBJECTIVE

Methylene blue (MB) is frequently administered during fiberoptic endoscopic evaluation of swallowing (FEES) to enhance visualization of pharyngeal bolus transit. However, the safety of MB is being questioned since serious adverse events (AEs) such as hemodynamic instability, hemolysis, and serotonin syndrome were reported. The aim of this study is a systematic analysis of the literature to obtain an evidence-based overview of AEs due to oral administration of MB and to determine its safety as a food dye during swallowing assessment.

METHODS

A systematic literature search was carried out in PubMed, Embase, and Cochrane Library. Two reviewers independently selected articles describing oral administration of MB as a main diagnostic/therapeutic intervention, dosage, and AEs. Expert opinions, conference papers, sample size < 10, and animal studies were excluded. Level of evidence of the included studies was determined.

RESULTS

A total of 2264 unduplicated articles were obtained. Seventeen studies met the inclusion criteria with 100% agreement between the two reviewers. Among these, twelve studies were randomized controlled trials. In a pooled population of 1902 patients receiving oral MB, three serious AEs were reported related to MB. Non-serious AEs showed a dose-related trend and were usually mild and self-limiting. A meta-analysis could not be performed as studies were methodologically too heterogeneous.

CONCLUSION

Serious AEs due to oral administration of MB are rare (n = 3, 0.16%). MB-related non-serious AEs are mild, self-limiting, and show a dose-related trend. These findings indicate that it is safe to use small amounts of MB as a food dye during swallowing examinations.

PEGylated BF2-Azadipyrromethene (NIR-AZA) fluorophores, for intraoperative imaging

Clinical imaging utilising near-infrared fluorescence is growing as an intraoperative aid for the decision-making processes during complex surgical procedures. Existing uses include perfusion assessment and lymph node identification with many new applications currently being proposed and developed. While imaging hardware and software have significantly progressed in recent times, suitable NIR-fluorophores remain a limiting factor. In this report, we describe the design, synthesis, photophysical characterization and in vivo imaging assessment of new PEGylated NIR-fluorophores based on the BF₂-azadipyrromethene fluorophore class. The synthetic route includes PEGylation as the final step, thereby allowing routine access to derivatives substituted with different molecular weights of PEG. Absorption and emission wavelength maxima in PBS lie at 690 and 720 nm respectively with quantum yields over 12%. They show excellent photostability and no light induced singlet oxygen production. A time-course of NIR-fluorescence imaging, post i.v. administration, in BALB/c mice showed a rapid and preferential accumulation in the renal excretion pathway within 20 min, indicative of potential clinical usage for intraoperative identification of vial structures along this pathway. Assessment with clinical imaging equipment showed the NIR-AZA fluorophores to be wavelength compatible and brighter than currently used methylene blue (MB), and that they have the ability to be imaged simultaneously with indocyanine green (ICG) offering a potential for dual colour clinical imaging.

Screening and surveillance methods for dysplasia in inflammatory bowel disease patients: Where do we stand?

Patients with long-standing ulcerative colitis (UC) and extensive Crohn’s colitis (CC) are at increased risk for dysplasia and colorectal cancer (CRC). Several studies have shown that UC extending proximal to the rectum, CC involving at least 1/3 of the colon, co-existence of primary sclerosing cholangitis, undetermined or unclassified colitis, family history of CRC and young age at diagnosis appear to be independent risk factors for inflammatory bowel disease (IBD) - related CRC. Therefore, screening and surveillance for CRC in IBD patients is highly recommended by international and national guidelines, whilst colonoscopy remains the unequivocal tool in order to detect potentially resectable dysplastic lesions or CRC at an early stage. Although the importance of screening and surveillance is widely proven, there is a controversy regarding the time of the first colonoscopy and the criteria of who should undergo surveillance. In addition, there are different recommendations among scientific societies concerning which endoscopic method is more efficient to detect dysplasia early, as well as the terminology for reporting visible lesions and the management of those lesions. This article concisely presents the main endoscopic methods and techniques performed for detecting dysplasia and CRC surveillance in patients with IBD focusing on their evidence-based accuracy and efficiency, as well as their cost-effectiveness. Finally, newer methods are mentioned, highlighting their applicability in daily endoscopic practice.

Methylene blue MMX® tablets for chromoendoscopy. Bioavailability, colon staining and safety in healthy volunteers undergoing a full colonoscopy

Methylene blue-MMX® tablets are proposed as an aid for detection and visualisation of adenomas and carcinomas in patients undergoing colonoscopy, by improving their detection rate and highlighting the presence of the intestinal dysplastic lesions. Single total doses of 100 and 200 mg were administered to healthy volunteers undergoing a bowel cleansing preparation and a full colonoscopy to investigate the colonic staining. The pharmacokinetics of methylene blue and the safety after exposure to the tablets were also investigated. With 200 mg, the best staining, assessed as the sum of acceptable and good staining, was achieved in the ascending colon and rectosigmoid (75% subjects each), the transverse and the descending colon (approximately 63% each). Absence of staining or overstaining were reported for no colonic region of interest in any subject. Similar results were observed in the 100 mg dose group. Methylene blue blood concentrations reached a peak (C_max) in a median time (T_max) of 12 h with 100 mg and 16 h with 200 mg. AUC_0-t was 10.7 ± 6.7 μg/mLxh after 100 mg and 25.2 ± 7.4 μg/mLxh after 200 mg. Half-life ranged between 9 and 22 h after the lower dose and between 6 and 26 h after the higher dose. The cumulative urinary excretion was about 28% after 100 mg and about 39% after 200 mg up to 60 h post-dose. The overall frequency of adverse events after single dose of the test product administered along with a bowel cleansing preparation was 39%, but only one was related to the test product: abnormal transaminases. The most frequent adverse event was a transient polyuria (17%). One serious adverse event (gastrointestinal haemorrhage) led the subject to study discontinuation and hospitalisation and another subject withdrew the study due to one adverse event (haematemesis). Either event was not related to methylene blue.

An Update on Surveillance in Ulcerative Colitis

PURPOSE OF REVIEW

Patients with long-standing ulcerative colitis have an increased risk for the development of colorectal cancer (CRC). Colitis-related dysplasia appears to confer the greatest risk. Colonoscopic surveillance to detect dysplasia has been advocated by gastrointestinal societies. The aim of surveillance is the reduction of mortality and morbidity of CRC through detection and resection of dysplasia or detecting CRC at an earlier and potentially curable stage. Traditional surveillance has relied on mucosal assessment with targeted biopsy of visible lesions and random biopsy sampling on the premise that dysplasia was not visible at endoscopy. Advances in optical technology permitting increased detection of dysplasia and evidence that most dysplasia is visible has had practice-changing implications.

RECENT FINDINGS

Emerging evidence favours chromoendoscopy (CE) for dysplasia detection and is gaining wider acceptance through recent international (International Consensus Statement on Surveillance and Management of Dysplasia in Inflammatory Bowel Disease (SCENIC)) recommendations and endorsed by many gastrointestinal societies. Adoption of CE as the gold standard of surveillance has been met with by scepticism, from conflicting data, operational barriers and the need to understand the true impact of increasingly higher dysplasia detection on overall CRC mortality. Valid debate notwithstanding, implementation of a risk stratification protocol that includes CE is an effective approach allowing earlier detection of dysplasia and colorectal neoplasia, determination of surveillance intervals with appropriate allocation of resources and limiting morbidity from CRC and colonoscopy itself. Further prospective data should define the true and long-term impact of dysplasia detection with modern techniques.

Surveillance of patients with inflammatory bowel disease

Patients with inflammatory bowel disease involving the colon are at increased risk for developing colorectal cancer. Colonoscopy surveillance is important to identify and treat IBD associated dysplasia. The SCENIC consensus provides evidence-based recommendations for optimal surveillance and management of dysplasia in IBD. Chromoendoscopy, with the surface application of dyes to enhance mucosal visualization, is the superior endoscopic surveillance strategy to detect dysplasia. Most dysplasia is visible, and can be endoscopically resected. Future studies should determine the effect of new surveillance strategies on the incidence of CRC and mortality in patients with IBD.

Expert opinions and scientific evidence for colonoscopy key performance indicators

Colonoscopy is a widely performed procedure with procedural volumes increasing annually throughout the world. Many procedures are now performed as part of colorectal cancer screening programmes. Colonoscopy should be of high quality and measures of this quality should be evidence based. New UK key performance indicators and quality assurance standards have been developed by a working group with consensus agreement on each standard reached. This paper reviews the scientific basis for each of the quality measures published in the UK standards.

What Can We Do to Optimize Colonoscopy and How Effective Can We Be?

In the USA, colorectal cancer is the third most common cancer and third leading cause of cancer death among both men and women. Declining rates of colon cancer in the past decade have been attributed in part to screening and removal of precancerous polyps via colonoscopy. Recent emphasis has been placed on measures to increase the quality and effectiveness of colonoscopy. These have been divided into pre-procedure quality metrics (bowel preparation), procedural quality metrics (cecal intubation, withdrawal time, and adenoma detection rate), post-procedure metrics (surveillance interval), and other quality metrics (patient satisfaction and willingness to repeat the procedure). The purpose of this article is to review the data and controversies surrounding each of these and identify ways to optimize the performance of colonoscopy.

Measuring the bioactivity and molecular conformation of typically globular proteins with phenothiazine-derived methylene blue in solid and in solution: A comparative study using photochemistry and computational chemistry

Methylene blue is a phenothiazine agent, that possesses a diversity of biomedical and biological therapeutic purpose, and it has also become the lead compound for the exploitation of other pharmaceuticals such as chlorpromazine and the tricyclic antidepressants. However, the U.S. Food and Drug Administration has acquired cases of detrimental effects of methylene blue toxicities such as hemolytic anemia, methemoglobinemia and phototoxicity. In this work, the molecular recognition of methylene blue by two globular proteins, hemoglobin and lysozyme was characterized by employing fluorescence, circular dichroism (CD) along with molecular modeling at the molecular scale. The recognition of methylene blue with proteins appears fluorescence quenching via static type, this phenomenon does cohere with time-resolved fluorescence lifetime decay that nonfluorescent protein-drug conjugate formation has a strength of 10(4)M(-1), and the primary noncovalent bonds, that is hydrogen bonds, π-conjugated effects and hydrophobic interactions were operated and remained adduct stable. Meantime, the results of far-UV CD and synchronous fluorescence suggest that the α-helix of hemoglobin/lysozyme decreases from 78.2%/34.7% (free) to 58.7%/23.8% (complex), this elucidation agrees well with the elaborate description of three-dimensional fluorescence showing the polypeptide chain of proteins partially destabilized upon conjugation with methylene blue. Furthermore, both extrinsic fluorescent indicator and molecular modeling clearly exhibit methylene blue is situated within the cavity constituted by α1, β2 and α2 subunits of hemoglobin, while it was located at the deep fissure on the lysozyme surface and Trp-62 and Trp-63 residues are nearby. With the aid of computational analyses and combining the wet experiments, it can evidently be found that the recognition ability of proteins for methylene blue is patterned upon the following sequence: lysozyme<hemoglobin<albumin. Basically, the distinction originates from different spatial structures of proteins and noncovalent interactions between proteins and methylene blue. In addition, biological relevance of the biorecognition of methylene blue with proteins was briefly discussed. We hope that this study could provide further standpoint so that one explore the biological activity of methylene blue and also phenothiazines.

Improving the utility of colonoscopy: Recent advances in practice

Colonoscopy is a frequently performed diagnostic and therapeutic test and the primary screening tool in several nationalized bowel cancer screening programs. There has been a considerable focus on maximizing the utility of colonoscopy. This has occurred in four key areas: Optimizing patient selection to reduce unnecessary or low yield colonoscopy has offered cost-benefit improvements in population screening. Improving quality assurance, through the development of widely accepted quality metrics for use in individual practice and the research setting, has offered measurable improvements in colonoscopic yield. Significant improvements have been demonstrated in colonoscopic technique, from the administration of preparation to the techniques employed during withdrawal of the colonoscope. Improved techniques to avoid post-procedural complications have also been developed-further maximizing the utility of colonoscopy. The aim of this review is to summarize the recent evidence-based advances in colonoscopic practice that contribute to the optimal practice of colonoscopy.

New technologies and techniques to improve adenoma detection in colonoscopy

Adenoma detection rate (ADR) is a key component of colonoscopy quality assessment, with a direct link between itself and future mortality from colorectal cancer. There are a number of potential factors, both modifiable and non-modifiable that can impact upon ADR. As methods, understanding and technologies advance, so should our ability to improve ADRs, and thus, reduce colorectal cancer mortality. This article will review new technologies and techniques that improve ADR, both in terms of the endoscopes themselves and adjuncts to current systems. In particular it focuses on effective techniques and behaviours, developments in image enhancement, advancement in endoscope design and developments in accessories that may improve ADR. It also highlights the key role that continued medical education plays in improving the quality of colonoscopy and thus ADR. The review aims to present a balanced summary of the evidence currently available and does not propose to serve as a guideline.

Chromocolonoscopy

Chromoendoscopy techniques improve the visualization of mucosal structures. This article reviews and summarizes key studies addressing the impact of chromoendoscopy on colonic neoplasia detection and differentiation of neoplastic from non-neoplastic polyps in average and high-risk populations, including patients with colonic inflammatory bowel disease (IBD). In this context, there are convincing data that chromoendoscopy differentiates neoplastic from non-neoplastic polyps in average-risk populations with high accuracy. Moreover, dye-based chromoendoscopy improves neoplasia detection in colonic IBD surveillance.

Advances in colonoscopy

Colonoscopy with polypectomy has been established as the major prevention and detection strategy for colorectal cancer for over a decade. Over this period advances in colonoscopic imaging, polyp detection, prediction of histopathology and polypectomy techniques have all been seen; however, the true magnitude of the limitations of colonoscopy has only recently been widely recognized. The rate and location of missed or interval cancers after complete colonoscopy appears to be influenced by the operator-dependency of colonoscopy and failure of conventional practices to detect and treat adenomatous, and possibly more importantly, non-adenomatous colorectal cancer precursors. Consequently, studies that expand our understanding of these factors and advances that aim to improve colonoscopy, polypectomy, and cancer protection are of critical importance.

Advanced imaging in colonoscopy and its impact on quality

Detecting and resecting colonic polyps during endoscopy has been shown to reduce CRC. At the same time, endoscopy has faced substantial technical improvements and continues to undergo major changes. Detection of colorectal neoplasias is facilitated by using high-definition endoscopy, and characterization of lesions is more accurate by using virtual CE. High-definition endoscopy has found widespread use, whereas virtual CE is still more often used in tertiary centers and for high-risk patient groups. Endomicroscopy has opened the door for in vivo histology and functional as well as molecular imaging. Thorough training of the endoscopists is necessary, and redefined reimbursement codes may help make these techniques available in the clinical arena for high-risk patients who are most probable to benefit from the more advanced diagnostic endoscopy techniques. Over recent years, there has also been an increasing push by healthcare payors and providers to improve the quality of healthcare services. The ultimate goal of monitoring quality measures is to improve the overall health of the population and, for colon cancer screening, to reduce the incidence and mortality of colon cancer. However, the development of an appropriate quality measure and ensuring the accuracy of the data on which we base our efforts are among the first challenges that we must meet (Table 1). The continued technologic advancements in colonoscopy and endoscopic imaging may result in improvements in the quality of colonoscopy and should lead to a decrease in the incidence and mortality from colon cancer.

Advances in diagnostic and therapeutic colonoscopy

PURPOSE OF REVIEW

We review current studies on endoscopic and technologic advances for the detection and treatment of colorectal neoplasia.

RECENT FINDINGS

Improvements in adenoma detection have been shown to be possible with the use of high definition white light as well as water-related methods such as water exchange. Use of cap assist colonoscopy, when combined with water-related methods, has recently been shown to also improve the detection of adenomas. Narrow band imaging and confocal laser endomicroscopy may have an advantage of offering endoscopists the ability to make an 'optical diagnosis' with the possibility of discarding nonadenomatous tissue. Furthermore, educational interventions aimed at improving adenoma detection may have lasting effects on endoscopists' adenoma detection rates. Lastly, endoscopic mucosal resection and endoscopic submucosal dissection are being applied for the treatment of large colorectal polyps, obviating the need for surgery in most instances. However, further studies are needed to establish the optimal methods for polyp resection.

SUMMARY

Advances in endoscopic technology are being shown to enhance the detection of early cancers and precancerous lesions. However, these tools may be supplementary to a high-quality colonoscopy using excellent techniques, factors that are now being implemented in training programs.

Endoscopic mucosal imaging of gastrointestinal neoplasia in 2013

The holy grail of gastrointestinal endoscopy consists of the detection, in vivo characterization, and endoscopic removal of early or premalignant mucosal lesions. While our ability to achieve this goal has improved substantially since the development of the modern video-endoscope, inadequate visual inspection, errors of interpretation, and lesion subtlety all contribute to the continued suboptimal detection and assessment of early neoplasia. A myriad of new technologies has thus emerged that may help resolve these shortcomings; high magnification endoscopes, as well as the techniques of dye-based and virtual chromoendoscopy, are now widely available, while confocal laser endomicroscopy and endocystoscopy, optical coherence tomography, and autofluorescence imaging are generally applicable only in a research setting. Such technologies can be broadly categorized according to whether they potentially afford endoscopists improved detection, or real-time characterization, of mucosal lesions. Enhanced detection of otherwise "invisible" lesions, such as a flat area of intramucosal adenocarcinoma within Barrett's esophagus, carries the potential of an endoscopic cure prior to the development into a more advanced or metastatic disease. The ability to characterize a lesion to achieve an in vivo diagnosis, such as a colonic polyp, potentially affords endoscopists the ability to decide which lesions require removal and which can be safely left behind or discarded without histological assessment. Furthermore targeted biopsies, such as in the surveillance of chronic colitis, may prove to be more accurate and efficacious than the current protocol of random biopsies. An important caveat in the discussion of developing technologies in early cancer detection is the fundamental importance of a health-care system that promotes screening programs to recruit at-risk individuals. The ideal tool to optimize the use of endoscopy in population screening would be a panel of reliable biomarkers (blood, stool, or urine) that could effectively select a high-risk group, thus reducing the indiscriminate use of an expensive technology. The following review summarizes the current endoscopic imaging techniques available, and in development, for the early identification of gastrointestinal neoplasia.

Chromocolonoscopy

Chromocolonoscopy is the process of endoscopically examining the colon mucosa after it has been stained with dye. The goal is to allow the endoscopist to identify subtle features in the mucosa, such as morphologically flat polyps or crypt patterns. Studies examining the efficacy of chromocolonoscopy to identify adenomas missed by conventional colonoscopy have shown that although chromocolonoscopy increases polyp yield, most additional lesions are small in size. Staining can also help in differentiating neoplastic from non-neoplastic polyps. Perhaps the most useful aspect of chromocolonoscopy is increasing the yield for dysplasia in patients undergoing colonoscopy for inflammatory bowel disease surveillance.

Update on colonoscopy preparation, premedication and sedation

The advent of optical colonoscopy has enabled gastroenterologists to visualize the colonic mucosa. This procedure has since become the cornerstone of colon cancer screening programs. Clinicians and scientists have made great strides to fine-tune the technical aspects of this procedure and have also made important advances that allow for a more effective and safer colonoscopy. This article focuses on current research and expert opinion regarding colonoscopy preparation, premedication and sedation.