mesalazine

Overview

Mesalazine, also known as mesalamine or 5-aminosalicylic acid (5-ASA), is an anti-inflammatory therapeutic agent used primarily in the management of inflammatory bowel diseases, especially ulcerative colitis. It acts locally within the intestinal lumen and colonic mucosa, where it helps suppress inflammatory signaling and reduce mucosal injury. In pharmaceutical development, mesalazine is notable for its high oral dose requirement and for the need to deliver the drug to the colon while minimizing premature release in the upper gastrointestinal tract.

From a formulation and biopharmaceutic perspective, mesalazine is a challenging active pharmaceutical ingredient because its therapeutic effect depends strongly on dissolution behavior, gastrointestinal pH, fluid volume, buffer capacity, transit time, and product design. Recent work has continued to examine how its physicochemical properties, including particle size, crystal habit, crystallinity, wetting, and packing, influence performance in oral and rectal dosage forms.

Focus of Latest Publications

Recent research on mesalazine has focused on optimizing its pharmaceutical properties and delivery to improve therapeutic efficacy in inflammatory bowel disease. As a BCS class IV drug with high unit doses (up to 4000 mg), mesalazine formulations are subject to significant bioavailability challenges. Recent studies have demonstrated that physical properties of the drug substance—including crystal morphology, particle size, and solid-state characteristics—critically influence dissolution behavior, wetting, and tablet packing. Evaluation of mesalazine APIs from multiple manufacturers revealed distinct crystal habits (needles, rectangular bars, and mixed morphologies) that affect surface polarity and dissolution performance, with rectangular bar crystal morphology showing superior biopharmaceutical properties and favorable manufacturing characteristics for dosage forms.

Dissolution testing has emerged as a key focus area for understanding mesalazine performance. Research examining the influence of dissolution media parameters—including pH, molarity, and buffer capacity—on mesalazine release profiles has shown that conventional dissolution tests often overpredict in vivo performance. Studies comparing prolonged-release granules and Multi-Matrix formulations revealed that low-molarity buffer systems provide discriminatory power to detect differences between reference products and generics, particularly for MMX tablets, underscoring the importance of appropriate dissolution methods for bioequivalence assessment and generic drug development.

Novel drug delivery platforms incorporating mesalazine or its active metabolite 5-aminosalicylic acid (5-ASA) have advanced toward addressing intestinal targeting and controlled release. Hypoxia-responsive delivery systems and probiotic-based encapsulation approaches have demonstrated improved sustained release of 5-ASA at sites of inflammation, with enhanced therapeutic efficacy and reduced side effects in murine colitis models. Additionally, bioanalytical method development for rectal mesalazine suppositories using in vitro permeation testing with excised mucosal tissue has established feasible surrogates for evaluating local drug bioavailability.

Clinically, mesalazine continues to be used as background therapy in combination with emerging treatment modalities. Recent evidence indicates that concomitant 5-ASA does not significantly affect time to clinical remission in patients with ulcerative colitis receiving Janus kinase inhibitors, supporting its continued use as adjunctive therapy in combination regimens without compromising efficacy of newer anti-inflammatory agents.