# Drugs for Inflammatory Bowel Disease > Drugs for inflammatory bowel disease in MBBS Pharmacology: mesalazine delivery, steroids, azathioprine metabolism and anti-TNF therapy rules. - Canonical URL: https://prepelephant.com/topics/mbbs/pharmacology/drugs-for-inflammatory-bowel-disease - Exam / course: MBBS · Subject: Pharmacology - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-02 - Last updated: 2026-10-02 - How to cite: "Drugs for Inflammatory Bowel Disease", PrepElephant, https://prepelephant.com/topics/mbbs/pharmacology/drugs-for-inflammatory-bowel-disease ## Direct answer Where the inflammation sits dictates both drug and delivery in inflammatory bowel disease: ulcerative colitis is a mucosal surface disease that mesalazine reaches topically — rectal preparations for proctitis, oral plus topical for left-sided disease — while Crohn's transmural inflammation demands systemic immunosuppression earlier. Corticosteroids induce remission but never maintain it; thiopurines (azathioprine) maintain steroid-free remission slowly, over two to three months; anti-TNF agents (infliximab, adalimumab) rescue refractory disease, with the gut-selective vedolizumab as the targeted alternative. Severity sets urgency: intravenous steroids with ciclosporin or infliximab rescue for acute severe colitis, colectomy when rescue fails. ## What you must remember - **Mesalazine logic:** active 5-aminosalicylic acid delivered to the site — suppositories and enemas for proctitis and left-sided disease, oral delayed-release for extensive colitis; the combination beats either alone. - **Sulfasalazine costs:** the sulfa carrier brings rash, reversible oligospermia, orange discolouration of urine and tears, and folate interference — prescribe folic acid with it. - **Steroid ceiling:** prednisolone about 40 mg to induce, never to maintain — budesonide with ileal release spares systemic exposure. - **Azathioprine package:** onset 8-12 weeks; leukopenia (check TPMT and NUDT15 genetics where available), pancreatitis, hepatitis, and a small lymphoma excess; monitor counts and liver throughout. - **Anti-TNF discipline:** infliximab at weeks 0, 2 and 6 then 8-weekly, combined with azathioprine (SONIC); screen every patient for latent tuberculosis and hepatitis B before the first dose. - **Vedolizumab:** anti-alpha-4-beta-7 integrin, gut-selective lymphocyte blockade — systemic infection risk lower than anti-TNF. - **Acute severe colitis:** intravenous hydrocortisone; assess at day three (stool frequency, CRP, radiology); rescue with ciclosporin 2 mg/kg or infliximab, with colectomy ready. - **Crohn's extras:** weekly methotrexate with folate (never daily dosing), exclusive enteral nutrition as first-line induction in paediatric Crohn's. ## Escalating therapy in a ulcerative colitis patient A woman with left-sided colitis flares with blood and urgency. Step one: oral mesalazine plus a mesalazine enema, because topical plus oral outperforms either alone. She improves; maintenance mesalazine continues. Two flares within a year, or steroid dependence when prednisolone tapers — the definition that changes everything — trigger azathioprine, started while tapering steroids because its benefit takes two months. A year later she flares on azathioprine: anti-TNF or vedolizumab enter, after tuberculosis screening. Should she present toxic with 12 bloody stools and a dilating colon, the pathway compresses to hours — admission, intravenous steroids, day-three assessment, ciclosporin or infliximab rescue, and a surgeon consulted on day one, not day seven. The Crohn's mirror runs one step ahead systemically: steroids and nutrition induce, thiopurines or methotrexate maintain, biologics rescue, and smoking cessation is the cheapest maintenance drug in the list. ## The Indian angle: tuberculosis before biologics India's latent tuberculosis burden makes pre-biologic screening the most tested and most consequential step in this chapter: chest radiograph, tuberculin or IGRA testing per local guidance, and in many Indian centres treatment of latent tuberculosis before or with anti-TNF initiation. Indian gastroenterology consensus guidance is explicit that infliximab-related tuberculosis reactivation is disproportionately disseminated and extrapulmonary. Biosimilar infliximab and adalimumab transformed access in India's private sector; azathioprine remains the public-sector maintenance backbone. Report thiopurine leukopenia and tuberculosis reactivation to the PvPI. ## Frequently asked questions ### Why are steroids never used as maintenance therapy in IBD? They lose efficacy and accumulate toxicity — osteoporosis, diabetes, infection — without preventing relapse; maintenance belongs to mesalazine, thiopurines or biologics. ### Why screen for tuberculosis before anti-TNF therapy? TNF blockade reactivates latent tuberculosis at high rates; in India's high-burden setting, reactivation is often disseminated — screen, treat latent infection, then start. ### What are sulfasalazine's specific adverse effects beyond mesalazine? The sulphasalazine carrier causes rash, reversible oligospermia, orange discolouration of secretions and folate depletion; supplement folic acid. ### How is acute severe ulcerative colitis rescued after steroid failure? Intravenous ciclosporin 2 mg/kg or infliximab as rescue therapy around day three, with colectomy available if response is absent — a joint surgical decision from admission. ### What makes vedolizumab mechanistically distinct? It blocks alpha-4-beta-7 integrin selectively in gut lymphocyte trafficking, sparing systemic immunity — fewer systemic infections than anti-TNF.