1. Song EM, Yang SK. Natural history of inflammatory bowel disease: a comparison between the East and the West. Intest Res 2021. Dec. 2. [Epub]. https://doi.org/10.5217/ir.2021.00104 .

2. Bryant RV, Brain O, Travis SP. Conventional drug therapy for inflammatory bowel disease. Scand J Gastroenterol 2015;50:90–112.

3. Park J, Park S, Lee SA, Park SJ, Cheon JH. Improving the care of inflammatory bowel disease (IBD) patients: perspectives and strategies for IBD center management. Korean J Intern Med 2021;36:1040–1048.

4. Yoon JS, Lee SJ, Kim ES, Kim SK, Jung MK, Lee HS, et al. Quality of information on the Internet for Korean patients with inflammatory bowel disease. Korean J Intern Med 2019;34:1215–1222.

5. Turner D, Ricciuto A, Lewis A, et al. STRIDE-II: an update on the Selecting Therapeutic Targets in Inflammatory Bowel Disease (STRIDE) Initiative of the International Organization for the Study of IBD (IOIBD): determining therapeutic goals for treat-to-target strategies in IBD. Gastroenterology 2021;160:1570–1583.

6. Im JP, Ye BD, Kim YS, Kim JS. Changing treatment paradigms for the management of inflammatory bowel disease. Korean J Intern Med 2018;33:28–35.

7. Sood A, Ahuja V, Midha V, et al. Colitis and Crohn’s Foundation (India) consensus statements on use of 5-aminosalicylic acid in inflammatory bowel disease. Intest Res 2020;18:355–378.

8. Plosker GL, Croom KF. Sulfasalazine: a review of its use in the management of rheumatoid arthritis. Drugs 2005;65:1825–1849.

9. Di Paolo MC, Paoluzi OA, Pica R, et al. Sulphasalazine and 5-aminosalicylic acid in long-term treatment of ulcerative colitis: report on tolerance and side-effects. Dig Liver Dis 2001;33:563–569.

10. Mansfield JC, Giaffer MH, Cann PA, McKenna D, Thornton PC, Holdsworth CD. A double-blind comparison of balsalazide, 6.75 g, and sulfasalazine, 3 g, as sole therapy in the management of ulcerative colitis. Aliment Pharmacol Ther 2002;16:69–77.

11. Nielsen OH, Munck LK. Drug insight: aminosalicylates for the treatment of IBD. Nat Clin Pract Gastroenterol Hepatol 2007;4:160–170.

12. Berends SE, Strik AS, Lowenberg M, D’Haens GR, Mathot RA. Clinical pharmacokinetic and pharmacodynamic considerations in the treatment of ulcerative colitis. Clin Pharmacokinet 2019;58:15–37.

13. Shimodaira Y, Onochi K, Watanabe K, et al. Effect of acid-reducing agents on clinical relapse in ulcerative colitis with pH-dependent-released 5-aminosalicylic acid: a multicenter retrospective study in Japan. Intest Res 2021;19:225–231.

14. Thakral S, Thakral NK, Majumdar DK. Eudragit: a technology evaluation. Expert Opin Drug Deliv 2013;10:131–149.

15. Varum F, Freire AC, Bravo R, Basit AW. OPTICORE™, an innovative and accurate colonic targeting technology. Int J Pharm 2020;583:119372.

16. Nardelli S, Pisani LF, Tontini GE, Vecchi M, Pastorelli L. MMX® technology and its applications in gastrointestinal diseases. Therap Adv Gastroenterol 2017;10:545–552.

17. Sonu I, Lin MV, Blonski W, Lichtenstein GR. Clinical pharmacology of 5-ASA compounds in inflammatory bowel disease. Gastroenterol Clin North Am 2010;39:559–599.

18. Tamura S, Ishida N, Miyazu T, et al. Mesalazine granule formulation improves clinical data in Crohn’s disease compared with tablet formulation. Sci Rep 2020;10:21353.

19. Veloso PM, Machado R, Nobre C. Mesalazine and inflammatory bowel disease: from well-established therapies to progress beyond the state of the art. Eur J Pharm Biopharm 2021;167:89–103.

20. Peskar BM, Dreyling KW, May B, Schaarschmidt K, Goebell H. Possible mode of action of 5-aminosalicylic acid. Dig Dis Sci 1987;32(12 Suppl):51S–56S.

21. Wahl C, Liptay S, Adler G, Schmid RM. Sulfasalazine: a potent and specific inhibitor of nuclear factor kappa B. J Clin Invest 1998;101:1163–1174.

22. Rousseaux C, Lefebvre B, Dubuquoy L, et al. Intestinal anti-inflammatory effect of 5-aminosalicylic acid is dependent on peroxisome proliferator-activated receptor-gamma. J Exp Med 2005;201:1205–1215.

23. Couto D, Ribeiro D, Freitas M, Gomes A, Lima JL, Fernandes E. Scavenging of reactive oxygen and nitrogen species by the prodrug sulfasalazine and its metabolites 5-aminosalicylic acid and sulfapyridine. Redox Rep 2010;15:259–267.

24. Lamb CA, Kennedy NA, Raine T, et al. British Society of Gastroenterology consensus guidelines on the management of inflammatory bowel disease in adults. Gut 2019;68(Suppl 3):s1–s106.

25. Rubin DT, Ananthakrishnan AN, Siegel CA, Sauer BG, Long MD. ACG clinical guideline: ulcerative colitis in adults. Am J Gastroenterol 2019;114:384–413.

26. Choi CH, Moon W, Kim YS, et al. Second Korean guideline for the management of ulcerative colitis. Korean J Gastroenterol 2017;69:1–28.

27. Sandborn WJ, Regula J, Feagan BG, et al. Delayed-release oral mesalamine 4.8 g/day (800-mg tablet) is effective for patients with moderately active ulcerative colitis. Gastroenterology 2009;137:1934–1943.

28. Lichtenstein GR, Ramsey D, Rubin DT. Randomised clinical trial: delayed-release oral mesalazine 4.8 g/day vs. 2.4 g/day in endoscopic mucosal healing: ASCEND I and II combined analysis. Aliment Pharmacol Ther 2011;33:672–678.

29. Orchard TR, van der Geest SA, Travis SP. Randomised clinical trial: early assessment after 2 weeks of high-dose mesalazine for moderately active ulcerative colitis: new light on a familiar question. Aliment Pharmacol Ther 2011;33:1028–1035.

30. Ford AC, Khan KJ, Achkar JP, Moayyedi P. Efficacy of oral vs. topical, or combined oral and topical 5-aminosalicylates, in Ulcerative Colitis: systematic review and meta-analysis. Am J Gastroenterol 2012;107:167–176.

31. Osterman MT, Aberra FN, Cross R, et al. Mesalamine dose escalation reduces fecal calprotectin in patients with quiescent ulcerative colitis. Clin Gastroenterol Hepatol 2014;12:1887–1893.

32. d’Albasio G, Pacini F, Camarri E, et al. Combined therapy with 5-aminosalicylic acid tablets and enemas for maintaining remission in ulcerative colitis: a randomized double-blind study. Am J Gastroenterol 1997;92:1143–1147.

33. Feagan BG, Macdonald JK. Oral 5-aminosalicylic acid for induction of remission in ulcerative colitis. Cochrane Database Syst Rev 2012;10:CD000543.

34. Feagan BG, MacDonald JK. Once daily oral mesalamine compared to conventional dosing for induction and maintenance of remission in ulcerative colitis: a systematic review and meta-analysis. Inflamm Bowel Dis 2012;18:1785–1794.

35. Kruis W, Kiudelis G, Racz I, et al. Once daily versus three times daily mesalazine granules in active ulcerative colitis: a double-blind, double-dummy, randomised, non-inferiority trial. Gut 2009;58:233–240.

36. Tripathi K, Dong J, Mishkin BF, Feuerstein JD. Patient preference and adherence to aminosalicylates for the treatment of ulcerative colitis. Clin Exp Gastroenterol 2021;14:343–351.

37. Mizuno S, Ono K, Mikami Y, et al. 5-Aminosalicylic acid intolerance is associated with a risk of adverse clinical outcomes and dysbiosis in patients with ulcerative colitis. Intest Res 2020;18:69–78.

38. Lim WC, Wang Y, MacDonald JK, Hanauer S. Aminosalicylates for induction of remission or response in Crohn’s disease. Cochrane Database Syst Rev 2016;7:CD008870.

39. Akobeng AK, Zhang D, Gordon M, MacDonald JK. Oral 5-aminosalicylic acid for maintenance of medically-induced remission in Crohn’s disease. Cochrane Database Syst Rev 2016;9:CD003715.

40. Honap S, Sharma E, Samaan MA. 5-ASAs in Crohn’s disease: time to stop the salicylate? Dig Dis Sci 2022;67:2699–2700.

41. Coward S, Kuenzig ME, Hazlewood G, et al. Comparative effectiveness of mesalamine, sulfasalazine, corticosteroids, and budesonide for the induction of remission in Crohn’s disease: a Bayesian network meta-analysis: republished. Inflamm Bowel Dis 2017;23:E26–E37.

42. Bernstein CN, Tenakoon A, Singh H, Targownik LE. Continued 5ASA use after initiation of anti-TNF or immunomodulator confers no benefit in IBD: a population-based study. Aliment Pharmacol Ther 2021;54:814–832.

43. Xie C, Quan R, Hong F, Zou K, Yan W, Fu Y. The culprit of mesalamine intolerance: case series and literature review. BMC Gastroenterol 2019;19:138.

44. Tsujii Y, Nishida T, Osugi N, et al. Classification and clinical features of adverse drug reactions in patients with ulcerative colitis treated with 5-aminosalicylate acid: a single-center, observational study. Scand J Gastroenterol 2022;57:190–196.

45. Wild GE, Waschke KA, Bitton A, Thomson AB. The mechanisms of prednisone inhibition of inflammation in Crohn’s disease involve changes in intestinal permeability, mucosal TNFalpha production and nuclear factor kappa B expression. Aliment Pharmacol Ther 2003;18:309–317.

46. Baron JH, Connell AM, Kanaghinis TG, Lennard-Jones JE, Jones AF. Out-patient treatment of ulcerative colitis: comparison between three doses of oral prednisone. Br Med J 1962;2:441–443.

47. Waljee AK, Wiitala WL, Govani S, et al. Corticosteroid use and complications in a US inflammatory bowel disease cohort. PLoS One 2016;11:e0158017.

48. Buchman AL. Side effects of corticosteroid therapy. J Clin Gastroenterol 2001;33:289–294.

49. Maconi G, Camatta D, Cannatelli R, et al. Budesonide MMX in the treatment of ulcerative colitis: current perspectives on efficacy and safety. Ther Clin Risk Manag 2021;17:285–292.

50. Hibi T, Naganuma M, Oda E, et al. Predictive factors for achievement of mucosal healing by budesonide 2-mg foam in ulcerative colitis: a pooled analysis of data from two clinical trials. Intest Res 2020;18:56–68.

51. Van Assche G, Manguso F, Zibellini M, et al. Oral prolonged release beclomethasone dipropionate and prednisone in the treatment of active ulcerative colitis: results from a double-blind, randomized, parallel group study. Am J Gastroenterol 2015;110:708–715.

52. Lee YJ, Cheon JH, Kim JH, et al. Clinical efficacy of beclomethasone dipropionate in Korean patients with ulcerative colitis. Yonsei Med J 2017;58:144–149.

53. Lie MR, Kreijne JE, Dijkstra G, et al. No superiority of tacrolimus suppositories vs beclomethasone suppositories in a randomized trial of patients with refractory ulcerative proctitis. Clin Gastroenterol Hepatol 2020;18:1777–1784.

54. Caron B, Sandborn WJ, Panaccione R, et al. Efficacy of pharmacological agents for ulcerative proctitis: a systematic literature review. J Crohns Colitis 2022;16:922–930.

55. Nunes T, Barreiro-de Acosta M, Marin-Jimenez I, Nos P, Sans M. Oral locally active steroids in inflammatory bowel disease. J Crohns Colitis 2013;7:183–191.

56. Laine L, Hanauer SB. Considerations in the management of steroid-dependent Crohn’s disease. Gastroenterology 2003;125:906–910.

57. Velayos F, Mahadevan U. Management of steroid-dependent ulcerative colitis: immunomodulatory agents, biologics, or surgery? Clin Gastroenterol Hepatol 2007;5:668–671.

58. Singh A, Mahajan R, Kedia S, et al. Use of thiopurines in inflammatory bowel disease: an update. Intest Res 2022;20:11–30.

59. Fraser AG, Orchard TR, Jewell DP. The efficacy of azathioprine for the treatment of inflammatory bowel disease: a 30 year review. Gut 2002;50:485–489.

60. Stournaras E, Qian W, Pappas A, et al. Thiopurine monotherapy is effective in ulcerative colitis but significantly less so in Crohn’s disease: long-term outcomes for 11 928 patients in the UK inflammatory bowel disease bioresource. Gut 2021;70:677–686.

61. Xu Z, Davis HM, Zhou H. Clinical impact of concomitant immunomodulators on biologic therapy: pharmacokinetics, immunogenicity, efficacy and safety. J Clin Pharmacol 2015;55:Suppl 3. S60–S74.

62. Smith MA, Blaker P, Marinaki AM, Anderson SH, Irving PM, Sanderson JD. Optimising outcome on thiopurines in inflammatory bowel disease by co-prescription of allopurinol. J Crohns Colitis 2012;6:905–912.

63. Louis E, Irving P, Beaugerie L. Use of azathioprine in IBD: modern aspects of an old drug. Gut 2014;63:1695–1699.

64. Gilissen LP, Wong DR, Engels LG, et al. Therapeutic drug monitoring of thiopurine metabolites in adult thiopurine tolerant IBD patients on maintenance therapy. J Crohns Colitis 2012;6:698–707.

65. Crouwel F, Buiter HJC, de Boer NK. There is still a place for optimised thiopurine therapy in IBD. Gut 2021;70:2207.

66. Chaparro M, Ordas I, Cabre E, et al. Safety of thiopurine therapy in inflammatory bowel disease: long-term follow-up study of 3931 patients. Inflamm Bowel Dis 2013;19:1404–1410.

67. Nagy F, Molnar T, Szepes Z, Farkas K, Nyari T, Lonovics J. Efficacy of 6-mercaptopurine treatment after azathioprine hypersensitivity in inflammatory bowel disease. World J Gastroenterol 2008;14:4342–4346.

68. Lees CW, Maan AK, Hansoti B, Satsangi J, Arnott ID. Tolerability and safety of mercaptopurine in azathioprine-intolerant patients with inflammatory bowel disease. Aliment Pharmacol Ther 2008;27:220–227.

69. Matsuoka K. NUDT15 gene variants and thiopurine-induced leukopenia in patients with inflammatory bowel disease. Intest Res 2020;18:275–281.

70. Chang JY, Park SJ, Jung ES, et al. Genotype-based treatment with thiopurine reduces incidence of myelosuppression in patients with inflammatory bowel diseases. Clin Gastroenterol Hepatol 2020;18:2010–2018.

71. Derijks LJ, Gilissen LP, Hooymans PM, Hommes DW. Review article: thiopurines in inflammatory bowel disease. Aliment Pharmacol Ther 2006;24:715–729.

72. Maeda T, Sakuraba H, Hiraga H, et al. Long-term efficacy and tolerability of dose-adjusted thiopurine treatment in maintaining remission in inflammatory bowel disease patients with NUDT15 heterozygosity. Intest Res 2022;20:90–100.

73. Haisma SM, Lijftogt T, Kindermann A, et al. Methotrexate for maintaining remission in paediatric Crohn’s patients with prior failure or intolerance to thiopurines: a multicenter cohort study. J Crohns Colitis 2015;9:305–311.

74. Huang Z, Chao K, Li M, et al. Methotrexate for refractory Crohn’s disease compared with thiopurines: a retrospective non-head-to-head controlled study. Inflamm Bowel Dis 2017;23:440–447.

75. Feuerstein JD, Isaacs KL, Schneider Y, et al. AGA clinical practice guidelines on the management of moderate to severe ulcerative colitis. Gastroenterology 2020;158:1450–1461.

76. Feagan BG, McDonald JW, Panaccione R, et al. Methotrexate in combination with infliximab is no more effective than infliximab alone in patients with Crohn’s disease. Gastroenterology 2014;146:681–688.

77. Lichtenstein GR, Loftus EV, Isaacs KL, Regueiro MD, Gerson LB, Sands BE. ACG clinical guideline: management of Crohn’s disease in adults. Am J Gastroenterol 2018;113:481–517.

78. Vulliemoz M, Brand S, Juillerat P, et al. TNF-alpha blockers in inflammatory bowel diseases: practical recommendations and a user’s guide: an update. Digestion 2020;101:Suppl 1. 16–26.

79. Gecse K, Khanna R, Stoker J, et al. Fistulizing Crohn’s disease: diagnosis and management. United European Gastroenterol J 2013;1:206–213.

80. Vaughn BP, Moss AC. Prevention of post-operative recurrence of Crohn’s disease. World J Gastroenterol 2014;20:1147–1154.

81. Oh SJ, Shin GY, Soh H, et al. Long-term outcomes of infliximab in a real-world multicenter cohort of patients with acute severe ulcerative colitis. Intest Res 2021;19:323–331.

82. Jung YS, Han M, Park S, Cheon JH. Impact of early anti-TNF use on clinical outcomes in Crohn’s disease: a nationwide population-based study. Korean J Intern Med 2020;35:1104–1113.

83. Schreiber S, Ben-Horin S, Leszczyszyn J, et al. Randomized controlled trial: subcutaneous vs intravenous infliximab CT-P13 maintenance in inflammatory bowel disease. Gastroenterology 2021;160:2340–2353.

84. Ogata H, Hagiwara T, Kawaberi T, Kobayashi M, Hibi T. Safety and effectiveness of adalimumab in the treatment of ulcerative colitis: results from a large-scale, prospective, multicenter, observational study. Intest Res 2021;19:419–429.

85. Hisamatsu T, Suzuki Y, Kobayashi M, et al. Long-term safety and effectiveness of adalimumab in Japanese patients with Crohn’s disease: 3-year results from a real-world study. Intest Res 2021;19:408–418.

86. Yu J, Park SJ, Kim HW, et al. Effectiveness and safety of golimumab in patients with ulcerative colitis: a multicenter, prospective, postmarketing surveillance study. Gut Liver 2021. Dec. 27. [Epub]. https://doi.org/10.5009/gnl210335 .

87. Murdaca G, Spano F, Contatore M, et al. Infection risk associated with anti-TNF-α agents: a review. Expert Opin Drug Saf 2015;14:571–582.

88. Alrajhi S, Germain P, Martel M, et al. Concordance between tuberculin skin test and interferon-gamma release assay for latent tuberculosis screening in inflammatory bowel disease. Intest Res 2020;18:306–314.

89. Hong HS, Jung J, Park SH, et al. Seroprevalence of viral infectious diseases and associated factors in Korean patients with inflammatory bowel diseases. Korean J Intern Med 2022;37:73–84.

90. Annese V, Beaugerie L, Egan L, et al. European Evidence-based Consensus: inflammatory bowel disease and malignancies. J Crohns Colitis 2015;9:945–965.

91. Phan H, Weideman RA, Cipher DJ, Feagins LA. Safety of tumor necrosis factor inhibitor use in patients with concomitant malignancy. Intest Res 2020;18:282–288.