Practical management of mild-to-moderate ulcerative colitis: an international expert consensus.

INTRODUCTION: Although there are well-defined guidelines for the management of mild-to-moderate ulcerative colitis (UC), there are still unmet needs. For this reason, we conducted an international expert consensus to standardize the management of patients with mild-to-moderate UC and provide practical guidance to clinicians. AREAS COVERED: Based on Delphi methodology, 15 statements were approved after two rounds of voting, addressing several aspects of disease management from sequencing to treatment duration, from monitoring to optimization techniques and safety profile. EXPERT OPINION: Growing knowledge of mild-to-moderate UC has led to the development of new ambitious outcomes such as histological remission and disease clearance. Furthermore, noninvasive tools for patient monitoring such as fecal calprotectin and intestinal ultrasound are now available. Their implementation in clinical practice will allow clinicians to tightly monitor disease activity and promptly adapt treatment, avoiding complications and disease progression and targeting better disease control.

Machine learning of Raman spectra predicts drug release from polysaccharide coatings for targeted colonic delivery.

Colonic drug delivery offers numerous pharmaceutical opportunities, including direct access to local therapeutic targets and drug bioavailability benefits arising from the colonic epithelium's reduced abundance of cytochrome P450 enzymes and particular efflux transporters. Current workflows for developing colonic drug delivery systems involve time-consuming, low throughput in vitro and in vivo screening methods, which hinder the identification of suitable enabling materials. Polysaccharides are useful materials for colonic targeting, as they can be utilised as dosage form coatings that are selectively digested by the colonic microbiota. However, polysaccharides are a heterogeneous family of molecules with varying suitability for this purpose. To address the need for high-throughput material selection tools for colonic drug delivery, we leveraged machine learning (ML) and publicly accessible experimental data to predict the release of the drug 5-aminosalicylic acid from polysaccharide-based coatings in simulated human, rat, and dog colonic environments. For the first time, Raman spectra alone were used to characterise polysaccharides for input as ML features. Models were validated on 8 unseen drug release profiles from new polysaccharide coatings, demonstrating the generalisability and reliability of the method. Further, model analysis facilitated an understanding of the chemical features that influence a polysaccharide's suitability for colonic drug delivery. This work represents a major step in employing spectral data for forecasting drug release from pharmaceutical formulations and marks a significant advancement in the field of colonic drug delivery. It offers a powerful tool for the efficient, sustainable, and successful development and pre-ranking of colon-targeted formulation coatings, paving the way for future more effective and targeted drug delivery strategies.

Randomized double-blind placebo-controlled study to evaluate the effect of long-acting mesalamine on postinfectious irritable bowel syndrome with diarrhea.

BACKGROUND: A subset of patients with irritable bowel syndrome (IBS) develop their symptoms after gastroenteritis, referred to as postinfectious IBS (PI-IBS). PI-IBS is associated with low-grade intestinal inflammation. Previous studies have evaluated mesalamine, an anti-inflammatory drug, in patients with IBS. We evaluated the efficacy of long-acting mesalamine in patients with PI-IBS. METHODS: Sixty-one patients who developed diarrhea-predominant IBS (IBS-D) after gastroenteritis were randomized to receive either 2.4 g of long-acting mesalamine or placebo daily for 8-weeks. The symptoms assessed were abdominal pain, bloating, stool frequency, stool consistency, severity of diarrhea and constipation, satisfaction with bowel habits, and IBS affecting or interfering with life. Quality-of-life (QOL) was assessed using the IBS-QOL questionnaire. The prespecified primary outcome variable was the overall bowel symptom score (BSS) after 8-weeks of treatment. Effect sizes were expressed as standardized mean differences (Cohen's d). RESULTS: Fifty-four patients completed the 8-week treatment (n = 28 mesalamine, n = 26 placebo), 49 (91%) were male, and age range 23-71 years (mean ± SD 43 ± 13). Mesalamine demonstrated superior efficacy compared to placebo on the primary outcome variable, overall BSS (Cohen's d = 0.57, p = 0.042). Mesalamine was also superior for the secondary outcome of how much IBS affects your life in general (d = 0.72, p = 0.01). For the secondary outcomes of IBS symptoms, 7 of the 7 symptoms had trends of mesalamine superiority. For the secondary outcomes of IBS-QOL subscales, 8 of 9 had trends of mesalamine superiority. CONCLUSION: In patients with PI-IBS, long-acting mesalamine demonstrated to be effective in reducing IBS symptoms and improving QOL.

Going Outside the Gut: Immune Thrombocytopenia Presenting as a Rare Extraintestinal Manifestation of Ulcerative Colitis.

A 26-year-old male with no significant medical history presented with hematochezia and was diagnosed with ulcerative colitis (UC) accompanied by immune thrombocytopenia (ITP) as an extraintestinal manifestation (EIM) of UC. This case report delves into the uncommon overlap between UC, a subtype of inflammatory bowel disease primarily affecting the colon and rectum, and ITP, an autoimmune condition leading to platelet destruction. The patient's atypical presentation and subsequent positive response to a treatment regimen targeting both UC and ITP underscores the necessity for a thorough and multifaceted diagnostic approach in individuals with UC, especially when faced with non-gastrointestinal symptoms like unexplained thrombocytopenia. The findings from this study enhance the understanding of UC's diverse manifestations and highlight its potential intersection with other autoimmune diseases, advocating for integrated care strategies in managing such intricate clinical cases.

Mucoadhesive Mesalamine Prodrug Nanoassemblies to Target Intestinal Macrophages for the Treatment of Inflammatory Bowel Disease.

While mesalamine, a 5-aminosalicylic acid (5-ASA), is pivotal in the management of inflammatory bowel disease (IBD) through both step-up and top-down approaches in clinical settings, its widespread utilization is limited by low bioavailability at the desired site of action due to rapid and extensive absorption in the upper gastrointestinal (GI) tract. Addressing mesalamine's pharmacokinetic challenges, here, we introduce nanoassemblies composed exclusively of a mesalamine prodrug that pairs 5-ASA with a mucoadhesive and cathepsin B-cleavable peptide. In an IBD model, orally administered nanoassemblies demonstrate enhanced accumulation and sustained retention in the GI tract due to their mucoadhesive properties and the epithelial enhanced permeability and retention (eEPR) effect. This retention enables the efficient uptake by intestinal pro-inflammatory macrophages expressing high cathepsin B, triggering a burst release of the 5-ASA. This cascade fosters the polarization toward an M2 macrophage phenotype, diminishes inflammatory responses, and simultaneously facilitates the delivery of active agents to adjacent epithelial cells. Therefore, the nanoassemblies show outstanding therapeutic efficacy in inhibiting local inflammation and contribute to suppressing systemic inflammation by restoring damaged intestinal barriers. Collectively, this study highlights the promising role of the prodrug nanoassemblies in enhancing targeted drug delivery, potentially broadening the use of mesalamine in managing IBD.

MMX mesalamine in ulcerative colitis: Major advantages towards classical mesalamine formulations.

Medical therapy is the cornerstone of ulcerative colitis (UC) management and aims to induce and maintain remission. In case of mild-to-moderate UC, mesalamine (5-ASA) is the first-line option. 5-ASA requires local release at the level of the inflamed mucosa to exert its therapeutic action. While rectal preparations are useful in distal colitis, in cases of UC of at least rectosigmoid extent, guidelines suggest the association of oral and rectal 5-ASA. Mesalamine with Multi Matrix System® technology (MMX mesalamine) is an oral, high-strength (1.2 g/tablet), once-daily formulation of 5-ASA, designed to provide delayed and prolonged release throughout the entire colon. Clinical trials demonstrated a strong efficacy in inducing and maintaining clinical and endoscopic remission in active mild-to-moderate UC. The efficacy is related to specific colonic drug-delivery, to its high-dosage and once-daily administration, thus improving patients' adherence and outcomes. The specific colonic-delivery is also associated with very low rates of systemic absorption and adverse events (AEs). With this comprehensive review we aimed to summarize current knowledge on MMX mesalamine in mild-to-moderate UC, in terms of clinical pharmacology, efficacy and safety, also compared to other 5-ASA products. In addition we provided an expert opinion on the topic, examining the implications on clinical practice.

The colon targeting efficacies of mesalazine medications and their impacts on the gut microbiome.

Successful treatment of ulcerative colitis (UC) is highly dependent on several parameters, including dosing regimen and the ability to deliver drugs to the disease site. In this study two strategies for delivering mesalazine (5-aminosalicylic acid, 5-ASA) to the colon were compared in an advanced in vitro model of the human gastrointestinal (GI) tract, the SHIME® system. Herein, a prodrug strategy employing bacteria-mediated drug release (sulfasalazine, Azulfidine®) was evaluated alongside a formulation strategy that utilised pH and bacteria-mediated release (5-ASA, Octasa® 1600 mg). SHIME® experiments were performed simulating both the GI physiology and colonic microbiota under healthy and inflammatory bowel disease (IBD) conditions, to study the impact of the disease state and ileal pH variability on colonic 5-ASA delivery. In addition, the effects of the products on the colonic microbiome were investigated by monitoring bacterial growth and metabolites. Results demonstrated that both the prodrug and formulation approaches resulted in a similar percentage of 5-ASA recovery under healthy conditions. On the contrary, during experiments simulating the GI physiology and microbiome of IBD patients (the target population) the formulation strategy resulted in a higher proportion of 5-ASA delivery to the colonic region as compared to the prodrug approach (P < 0.0001). Interestingly, the two products had distinct effects on the synthesis of key bacterial metabolites, such as lactate and short chain fatty acids, which varied according to disease state and ileal pH variability. Further, both 5-ASA and sulfasalazine significantly reduced the growth of the faecal microbiota sourced from six healthy humans. The findings support that the approach selected for colonic drug delivery could significantly influence the effectiveness of UC treatment, and highlight that drugs licensed for UC may differentially impact the growth and functioning of the colonic microbiota.

Endoscopic and clinicopathological features of segmental colitis associated with diverticulosis.

Objectives: Segmental colitis associated with diverticulosis (SCAD) has close endoscopic and pathological similarities to ulcerative colitis (UC) and Crohn's disease. Clinical data on SCAD are limited in Japan. We examined the endoscopic and clinicopathological features of patients with SCAD. Methods: This single-center retrospective study included 13 patients with SCAD between 2012 and 2022. Endoscopic findings were categorized as follows: type A (swollen red patches 5-10 mm at the top of mucosal folds), mild and moderate type B (mild-to-moderate UC-like findings), type C (aphthous ulcers resembling Crohn's disease), and type D (severe UC-like findings). Results: Overall, six, five, and two patients were diagnosed with type A, mild type B, and moderate type B disease, respectively. Among the type A cases, two spontaneously progressed to moderate type B and one escalated to type D, necessitating an emergency sigmoidectomy owing to perforation peritonitis, despite repeated antibiotic treatments. Histopathologically, diffuse neutrophil and lymphocyte infiltration with cryptitis were noted in all type A cases, whereas UC-like alterations were observed in type B and D cases. Seven type B cases were treated with oral 5-aminosalicylic acid and/or salazosulfapyridine. Clinical remission was achieved in three mild type B cases and one moderate type B case, while clinical relapse and remission were noted in three moderate type B cases. No anti-inflammatory treatment was required in three type A and two mild type B cases. Conclusions: Aggressive anti-inflammatory treatment should be considered for SCAD with UC-like findings due to the potential risk of severe ulceration, stenosis, and/or perforation.

Formulation, Characterization and In Vitro Evaluation of Mesalamine and Bifidobacterium bifidum Loaded Hydrogel Beads in Capsule System for Colon Targeted Delivery.

Mesalamine is a first-line drug for the treatment of inflammatory bowel diseases. However, its premature release associated with marketed formulations leads to adverse effects like gastric trouble, vomiting, and diarrhoea. To minimize these side effects, colon-targeted drug delivery is essential. Besides conventional pharmacotherapy, bifidogenic probiotics with anti-inflammatory activity has been reported to elicit a significant impact on the remission of ulcerative colitis. Bifidogenic probiotics being acid-labile necessitate developing a gastro-resistant formulation for enhancing the delivery of viable cells to the colon. The present study was aimed at developing a fixed-dose unit dosage form of mucoadhesive hydrogel beads loaded with mesalamine and Bifidobacterium bifidum further encapsulated in Eudragit® capsules for the targeted drug delivery at colonic pH. The hydrogel beads were prepared by ionotropic gelation, with the effect of single and dual-crosslinking approaches on various formulation characteristics studied. Standard size 00 Eudragit® gastro-resistant capsules were prepared and the dried beads were filled inside the capsule shells. The formulation was then evaluated for various parameters, including physicochemical characterization, in vitro biocompatibility and anti-inflammatory activity. No interaction was observed between the drug and the polymers, as confirmed through FTIR, XRD, and DSC analysis. The mean particle size of the beads was ~ 457-485 µm. The optimized formulation showed a drug entrapment efficiency of 95.4 ± 2.58%. The Eudragit® capsule shells disintegrated in approximately 13 min at pH 7.4. The mucoadhesive hydrogel beads sustained the drug release above 18 h, with 50% of the drug released by the end of 12 h. The optimized formulation demonstrated significant (p < 0.05) gastro-resistance, biocompatibility, sustained drug release, cell viability, and anti-inflammatory activity.

Personalized Approach to Chronic Antibiotic-Refractory Pouchitis: A Case Report and Review of the Literature.

Patients who undergo restorative proctocolectomy and ileoanal anastomosis can develop pouchitis as a common chronic complication. A rare subset of patients fails to respond to multiple antibiotic therapies and develop chronic antibiotic-refractory pouchitis (CARP). We present a case of a 45-year-old male with pouchitis refractory to chronic antibiotic therapy and histology demonstrating chronic inflammatory changes. Management involved mesalamine and probiotics, resulting in a positive clinical response and symptom absence on follow-up. This case highlights the intricacies of treating chronic pouchitis post ileoanal anastomosis, showcasing the efficacy of a personalized approach using mesalamine and probiotics. CARP is emerging as an entity associated with poor quality of life and increased healthcare costs. CARP fails to respond to multiple courses of antibiotic therapy. Therefore, the management of CARP is difficult and limited. Current literature on the management of CARP is scarce and mainly involves immunomodulatory therapy and probiotics. It is essential to keep this differential diagnosis in mind in patients with recurrent pouchitis episodes and start them on immunomodulator treatment and probiotics rather than repeated courses of antibiotics.

Achy Breaky Heart: A Rare Case of Myopericarditis Secondary to Mesalamine in a Patient With Inflammatory Bowel Disease.

Mesalamine is a first-line drug used in the treatment of inflammatory bowel disease (IBD), specifically ulcerative colitis (UC), with side effects ranging from gastrointestinal effects to cardiotoxicity. We present a rare case of mesalamine-induced myopericarditis in a patient with IBD, who presented with epigastric pain and was found to have elevated an c-reactive protein (CRP) in the absence of chest pain and any other gastrointestinal symptoms. This case highlights the importance of including myopericarditis as a differential for IBD patients on mesalamine with an isolated elevated CRP, especially within the first month of initiating this medication, as drug cessation usually leads to immediate clinical improvement.

The aminosalicylate - folate connection.

Two aminosalicylate isomers have been found to possess useful pharmacological behavior: p-aminosalicylate (PAS, 4AS) is an anti-tubercular agent that targets M. tuberculosis, and 5-aminosalicylate (5AS, mesalamine, mesalazine) is used in the treatment of ulcerative colitis (UC) and other inflammatory bowel diseases (IBD). PAS, a structural analog of pABA, is biosynthetically incorporated by bacterial dihydropteroate synthase (DHPS), ultimately yielding a dihydrofolate (DHF) analog containing an additional hydroxyl group in the pABA ring: 2'-hydroxy-7,8-dihydrofolate. It has been reported to perturb folate metabolism in M. tuberculosis, and to selectively target M. tuberculosis dihydrofolate reductase (mtDHFR). Studies of PAS metabolism are reviewed, and possible mechanisms for its mtDHFR inhibition are considered. Although 5AS is a more distant structural relative of pABA, multiple lines of evidence suggest a related role as a pABA antagonist that inhibits bacterial folate biosynthesis. Structural data support the likelihood that 5AS is recognized by the DHPS pABA binding site, and its effects probably range from blocking pABA binding to formation of a dead-end dihydropterin-5AS adduct. These studies suggest that mesalamine acts as a gut bacteria-directed antifolate, that selectively targets faster growing, more folate-dependent species.

Modified-Release Phosphatidylcholine (LT-02) for Ulcerative Colitis: Two Double-Blind, Randomized, Placebo-Controlled Trials.

BACKGROUND & AIMS: The aim of this study was to evaluate the efficacy of LT-02, a novel modified-release phosphatidylcholine (PC) formulation, for induction and maintenance of remission in patients with mild to moderate ulcerative colitis (UC) and inadequate response to mesalamine. METHODS: LT-02 was evaluated in a multicenter double-blind, randomized, placebo-controlled study comprising a 12-week induction trial (PCG-2), followed by a 48-week maintenance trial (PCG-4). In PCG-2, patients were randomized 1:1:1 to treatment with 0.8 g LT-02 4 times daily (QID), 1.6 g LT-02 twice daily (BID), or placebo, respectively. All patients continued to take a standard dose of oral mesalamine (≥2.4 g/day). The primary end point in PCG-2 was deep remission. Patients achieving remission at week 12 were randomly assigned 2:1:1 to 1.6 g LT-02 BID, placebo, or 500 mg mesalamine (3 times daily), respectively, in PCG-4; the primary end point was remission at 48 weeks. RESULTS: PCG-2 was terminated early for futility after a prespecified interim analysis; 466 patients (of 762 planned) were randomized. There was no statistically significant difference in deep remission at week 12 (placebo, 13.5%; LT-02 BID, 14.2%; LT-02 QID, 9.7%). In PCG-4, 150 patients (of approximately 400 planned) were randomized. There was no statistically significant difference in remission rates at week 48 (LT-02 BID, 49.3%; mesalamine, 50.0%; placebo, 43.2%). LT-02 was safe. CONCLUSIONS: Despite prior evidence of beneficial effects of PC in phase 2 trials, our induction study with LT-02 in patients with mild to moderate UC was terminated prematurely for futility. Signals of efficacy in maintenance therapy require confirmation in an adequately powered maintenance trial. LT-02 was safe and well-tolerated. CLINICALTRIALS: gov: NCT02280629, NCT02142725.

Systematic Review and Meta-analysis: Efficacy of Mesalamine in Irritable Bowel Syndrome.

BACKGROUND & AIMS: Some patients with irritable bowel syndrome (IBS) demonstrate low-grade inflammation in the intestine. Mesalamine, which has anti-inflammatory effects, may be an efficacious treatment for IBS, but studies are conflicting. We conducted a systematic review and meta-analysis to assess efficacy and safety of mesalamine in IBS. METHODS: We searched the medical literature up to September 14, 2022, to identify randomized controlled trials (RCTs) of mesalamine in IBS. We judged efficacy and safety using dichotomous assessments of effect on global IBS symptoms, abdominal pain, bowel habit or stool frequency, and occurrence of any adverse event. We pooled data using a random effects model, with efficacy and safety reported as pooled relative risks (RRs) with 95% confidence intervals (CIs). RESULTS: We identified 8 eligible RCTs (820 patients). Mesalamine was more efficacious than placebo for global IBS symptoms (RR of global symptoms not improving, 0.86; 95% CI, 0.79-0.95; number needed to treat = 10; 95% CI, 6-27), but not for abdominal pain or bowel habit or stool frequency. Subgroup analyses demonstrated efficacy of mesalamine in IBS with diarrhea for global IBS symptoms (RR, 0.88; 95% CI, 0.79-0.99), but not patients with other predominant bowel habits or those with post-infection IBS. Adverse event rates were no higher with mesalamine (RR, 1.20; 95% CI, 0.89-1.63) but were reported in only 5 trials. CONCLUSIONS: Mesalamine may be modestly efficacious for global symptoms in IBS, particularly IBS with diarrhea, but quality of evidence was low. Adequately powered high quality RCTs of mesalamine in IBS are needed.

Effects of Mesalamine Combined with Live Combined Bifidobacterium, Lactobacillus and Enterococcus Capsules on Intestinal Mucosa Barrier Function and Intestinal Microbiota in Mildly Active Crohn's Disease Patients.

Objective: This study is aimed at investigating the impact of mesalamine combined with Live combined Bifidobacterium, Lactobacillus and Enterococcus capsules on intestinal mucosa barrier function and intestinal microbiota in mildly active Crohn's disease patients.Methods: Ninety-six Crohn's disease patients in mild activity period were randomized into the control group (treated with mesalamine) and the observation group (treated with mesalamine combined with Live combined Bifidobacterium, Lactobacillus and Enterococcus capsules) (n = 48). After 4 wk of treatment, the patients were evaluated for their clinical efficacy. Intestinal microbiota counts, serum inflammatory factors, T lymphocyte subsets, and mucosal barrier function indicators in both groups were assessed.Results: After 4 wk of treatment, the total clinical effective rate of the observation group was higher than that of the control group. The number of Lactobacillus acidophilus (L. acidophilus) and Bifidobacterium Longum (B. longum) in the intestinal tract, serum IL-10 levels, and peripheral blood CD4+ and CD4+/CD8+ levels were higher, and the number of Bacteroides vulgatus (B. vulgatus), the levels of TNF-α, IL-6, CRP, CD8+, ET, D-lactate, DAO, and urine L/M ratio were lower in the observation group in comparison to those in the control group (all p < 0.05).Conclusion: Mesalamine combined with Live combined Bifidobacterium, Lactobacillus and Enterococcus capsules are more effective in treating mildly active Crohn's disease.

Dual stimuli-responsive delivery system for self-regulated colon-targeted delivery of poorly water-soluble drugs.

Inflammatory bowel disease (IBD) are chronic inflammatory conditions which cause significant patient morbidity. Local drug delivery to the colon can improve treatment efficacy and reduce side effects associated with IBD treatment. Smart drug delivery systems are designed to regulate the release of therapeutic agents at the desired site of action. pH-responsive drug carriers have been previously utilised for improved oral drug delivery beyond stomach harsh conditions. Additionally, the colon possesses a diverse microbiome secreting bioactive molecules e.g., enzymes, that can be exploited for targeted drug delivery. We herein synthesised and characterised a 2-hydroxyethyl methacrylate and methacrylic acid copolymer, crosslinked with an azobenzyl crosslinker, that displayed pH- and enzyme-responsive properties. The swelling and drug release from hydrogel were analysed in pH 1.2, 6.5 and 7.4 buffers, and in the presence of rat caecal matter using metronidazole and mesalamine as model BCS Class I and IV drugs, respectively. Swelling studies displayed pH-responsive swelling behaviour, where swelling was maximum at pH 7.4 and minimum at pH 1.2 (69 % versus 32 %). Consequently, drug release was limited in gastric and small intestinal conditions but increased significantly when exposed to colonic conditions containing caecal matter. This system displays promising capacity for achieving colon-targeted drug delivery with enhanced dissolution of poorly water-soluble drugs for local treatment of IBD and other colon-targeted therapies.

Oxidation of Mesalamine under Phenoloxidase- or Peroxidase-like Enzyme Catalysis.

Mesalamine, also called 5-ASA (5-aminosalicylic acid), is a largely used anti-inflammatory agent and is a main choice to treat Ulcerative Colitis. This report is aimed to investigate enzymatic processes involved in the oxidation of mesalamine to better understand some of its side-effects. Oxidation with oxygen (catalyzed by ceruloplasmin) or with hydrogen peroxide (catalyzed by peroxidase or hemoglobin) showed that these oxidases, despite their different mechanisms of oxidation, could recognize mesalamine as a substrate and trigger its oxidation to a corresponding quinone-imine. These enzymes were chosen because they may recognize hydroquinone (a p-diphenol) as substrate and oxidize it to p-benzoquinone and that mesalamine, as a p-aminophenol, presents some similarities with hydroquinone. The UV-Vis kinetics, FTIR and 1H NMR supported the hypothesis of oxidizing mesalamine. Furthermore, mass spectrometry suggested the quinone-imine as reaction product. Without enzymes, the oxidation process was very slow (days and weeks), but it was markedly accelerated with the oxidases, particularly with peroxidase. Cyclic voltammetry supported the hypothesis of the oxidative process and allowed a ranking of susceptibility to oxidizing mesalamine in comparison with other oxidizable drug molecules with related structures. The susceptibility to oxidation was higher for mesalamine, in comparison with Tylenol (acetaminophen) and with aspirin (salicylic acid).

Protective effect of Melissa officinalis against acetic acid-induced ulcerative colitis in rat models: an experimental study.

Background: Inflammation and oxidative activities within the gut play major roles in the pathogenesis of ulcerative colitis (UC). We aimed to determine the effect of Melissa officinalis, an antioxidant and anti-inflammatory agent, on the colon histological characteristics in acetic acid (AA)-induced UC in rat models. Methods: Thirty-six male rats with AA-induced colitis were divided into 5 groups: no treatment (AA); daily treatment with 300 mg/kg Melissa officinalis orally (MO) and rectally (MR); and 100 mg/kg mesalamine orally (AO) and rectally (AR). Macroscopic and histopathological evaluation of the colon, along with a biochemical laboratory evaluation, were performed 10 days after UC induction. Results: All treatment groups demonstrated lower macroscopic grading scores compared to the AA group. After treatment with MO, 42.9% of cases demonstrated no macroscopic changes, while 14.3% demonstrated only mucosal erythema. In the MR group 28.6% of rats had no changes in their mucosal lining and 28.6% had only mucosal erythema. Following histopathological evaluation, the AO group had lower scores regarding the severity of ulcer, inflammation, destruction, crypt abscess, and disorganization compared to the MO group. (P=0.02) The MR group demonstrated lower microscopic scores compared to the MO group, and also lower macroscopic scores compared to the AR group, although not significantly (P>0.05). Conclusions: Both oral and topical administration of Melissa officinalis have satisfactory healing properties compared to mesalamine, with topical route having better results. Therefore, further studies are needed to establish the benefit of Melissa officinalis administration (both orally and topically) within a UC treatment protocol.