Published: 1 December 2022

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Microscopic colitis – could it be caused by a medicine?

Prescriber Update 43(4): 56–57
December 2022

Microscopic colitis

Microscopic colitis is an inflammatory disease of the colon that causes chronic, watery, non-bloody diarrhoea.¹ Patients often experience between 4 and 9 watery stools per day, but in rare cases, this number can exceed 15.^1,2

Whilst the origin of microscopic colitis is largely unknown, it is likely to be multifactorial. Medicines, tobacco and autoimmune conditions have been identified as possible causes.² There is evidence that a mucosal immune response occurs in genetically predisposed individuals and may contribute to the development of microscopic colitis.¹ Diarrhoea associated with microscopic colitis is likely caused by mucosal inflammation.¹ Microscopic colitis predominantly affects females and should be considered a possible cause of chronic diarrhoea, especially in middle-aged and older adults.^1,2

There are two main subtypes of microscopic colitis, and each subtype is based on distinct histopathologic features:^1–3

• collagenous colitis – a layer of collagen develops in colon tissue
• lymphocytic colitis – the number of lymphocytes (white blood cells) increases in colon tissue.

Collagenous colitis is diagnosed in cases where a broad subepithelial fibrous band is observed on histology.⁴ Lymphocytic colitis is diagnosed when an infiltration of more than 20 intraepithelial lymphocytes per 100 epithelial cells is observed.⁴ Diarrhoea, normal colonoscopy results and microscopic abnormalities in the colon are characteristics of both subtypes.^4,5 Biopsies confirm a diagnosis.¹

Medicines associated with microscopic colitis

The list below provides examples of medicines associated with microscopic colitis (list not exhaustive).

• Non-steroidal anti-inflammatory drugs (NSAIDs): ibuprofen, diclofenac^{2, 6-8}
• Proton pump inhibitors: lansoprazole, omeprazole^{2, 6-8}
• Histamine-2 receptor antagonists: ranitidine, famotidine^2,9
• Selective serotonin reuptake inhibitors: sertraline, citalopram^{2, 6-8}
• Aspirin⁷
• Clozapine⁷
• Statins: simvastatin, atorvastatin¹
• Immune checkpoint inhibitors: pembrolizumab^1,10

Concomitant use of proton pump inhibitors and NSAIDs may also increase the risk of microscopic colitis.¹ Medicines associated with microscopic colitis are also associated with diarrhoea as a side effect.⁴ Healthcare professionals should consider such medicines as a possible cause of microscopic colitis.¹

References

1. Dietrich CF. 2022. Microscopic (lymphocytic and collagenous) colitis: clinical manifestations, diagnosis, and management. In: UpToDate 20 July 2022. URL: uptodate.com/contents/microscopic-lymphocytic-and-collagenous-colitis-clinical-manifestations-diagnosis-and-management (accessed 22 September 2022).
2. Shor J, Churrango G, Hosseini N, et al. 2019. Management of microscopic colitis: challenges and solutions. Clinical and Experimental Gastroenterology 12: 111-20. DOI: 10.2147/CEG.S165047 (accessed 14 July 2022).
3. Mayo Clinic. 2021. Microscopic colitis 20 January 2021. URL: mayoclinic.org/diseases-conditions/microscopic-colitis/symptoms-causes/syc-20351478 (accessed 12 July 2022).
4. Lucendo AJ. 2017. Drug exposure and the risk of microscopic colitis: a critical update. Drugs in R & D 17(1): 79-89. DOI: 10.1007/s40268-016-0171-7 (accessed 20 September 2022).
5. Zhang S-W, Xu R-H and Chen D. 2022. Drug exposure and risk of microscopic colitis: a systematic review and meta-analysis. Digestive Diseases (accepted, unedited manuscript). DOI: 10.1159/000526809 (accessed 20 September 2022).
6. Nguyen GC, Smalley WE, Vege SS, et al. 2016. American Gastroenterological Association Institute Guideline on the Medical Management of Microscopic Colitis. Gastroenterology 150(1): 242-6. DOI: 10.1053/j.gastro.2015.11.008 (accessed 20 September 2022).
7. American Gastroenterological Association. 2016. AGA Institute Guideline on the Management of Microscopic Colitis: Clinical Decision Support Tool. Gastroenterology 150(1): 276. DOI: 10.1053/j.gastro.2015.11.033 (accessed 22 September 2022).
8. Hamdeh S, Micic D and Hanauer S. 2021. Drug-induced colitis. Clinical Gastroenterology Hepatology 19(9): 1759-79. DOI: 10.1016/j.cgh.2020.04.069 (accessed 29 September 2022).
9. D'Sa FF, Fernandes EZ, Kesarkar SV, et al. 2022. Use of histamine-2 receptor antagonists and risk of inflammatory bowel diseases: a systematic review and meta-analysis of observational studies. Journal of Clinical Pharmacy and Therapeutics 47(8): 1103-11. DOI: 10.1111/jcpt.13662 (accessed 13 October 2022).
10. Choi K, Abu-Sbeih H, Samdani R, et al. 2019. Can immune checkpoint inhibitors induce microscopic colitis or a brand new entity? Inflammatory Bowel Diseases 25(2): 385-93. DOI: 10.1093/ibd/izy240 (accessed 13 October 2022).