Safety, Pharmacokinetics, and Bioequivalence Characterization of Two Different Strengths of Mesalazine Gastro-Resistant Tablets

<b>Background/Objectives</b>: Ulcerative colitis (UC), a chronic inflammatory bowel disease, affects approximately 5 million individuals worldwide, exerting a considerable influence on global health and economic systems. Among the challenges in UC management, treatment non-adherence stands out as a critical issue, often compromising therapeutic efficacy. One strategy to address this challenge is by reducing pill burden, which may improve patient compliance and optimize treatment outcomes. <b>Methods</b>: This randomized, two-sequence, four-period, crossover replicate study evaluated the pharmacokinetic profiles, bioequivalence, and safety of a newly developed 1500 mg mesalazine gastro-resistant tablet compared to three of the reference 500 mg Claversal^® gastro-resistant tablets (total dose 1500 mg) in 80 healthy participants under fasted conditions. <b>Results</b>: Bioequivalence between mesalazine formulations was observed in both the rate and extent of systemic bioavailability. The geometric mean ratios and their 90% CI were 102.51% (95.85-109.63) for AUC_0-∞, 103.36% (96.40-110.83) for AUC_0-t, 84.49% (78.24-91.24) for AUC_8-48h, and 114.24% (100.15-130.32) for C_max. All within the accepted bioequivalence ranges, confirming comparable pharmacokinetic performance. Secondary pharmacokinetic parameters such as t_max, t_1/2, K_e, Cl, and MRT were also consistent across both formulations. The incidence of adverse events was comparable between the two mesalazine formulations, with only flatulence and mild self-limited rash considered possibly related to test treatment. <b>Conclusions</b>: Overall, the 1500 mg formulation demonstrated a pharmacokinetic profile and tolerability comparable to the reference formulation, offering a higher-strength option to reduce daily pill burden. This strategy is of clinical relevance, particularly for improving treatment adherence among UC patients who need to take multiple pills daily to achieve their required dosage. While adherence is influenced by various factors, reducing pill burden may facilitate compliance and optimize therapeutic efficacy.