Inflammatory Bowel Disease(IBD) Physio+Pharm

Ulcerative colitis distribution

Always involves the rectum; continuous proximal spread; limited to colon, inflammation limited to mucosa and submucosa

Crohn’s disease distribution

Anywhere mouth→anus; skip lesions; rectal sparing common. Inflammation can involve the entire bowel wall

Ulcerative Colitis depth of inflammation

Mucosa + submucosa only.

Crohn’s depth of inflammation

Transmural; fistulas, strictures, abscesses.

Ulcerative Colitis presentation

Bloody diarrhea, urgency, tenesmus.

Crohn’s presentation

RLQ pain, diarrhea, weight loss.

UC endoscopy

Continuous inflammation, friable mucosa, pseudopolyps.

Crohn’s endoscopy

Cobblestoning, deep linear ulcers, skip lesions.

UC histology

Crypt abscesses.

Crohn’s histology

Non‑caseating granulomas (40%).

UC serology (just for step)

p‑ANCA positive.

Crohn’s serology (just for step)

ASCA positive.

Extraintestinal manifestations of IBD

Erythema nodosum, pyoderma gangrenosum, aphthous ulcers, episcleritis, uveitis, peripheral arthritis, ankylosing spondylitis, PSC.

5‑ASA mechanism+uses+AE

Topical anti‑inflammatory; decreases prostaglandins, leukotrienes, cytokines. Mild‑moderate UC; limited role in Crohn’s. Headache, nausea; safe

Sulfasalazine mechanism+uses+AE

ASA+sulfa; used as topical antiinflammatory just like ASA just metabilized better; AE:→ folate deficiency, sulfa allergy.

Thiopurines (Azathioprine/6‑MP) mechanism

Inhibit DNA synthesis in lymphocytes. AE: Leukopenia, pancreatitis, lymphoma; TPMT testing required.

Methotrexate mechanism + AEs

DHFR inhibitor → ↓ lymphocyte proliferation. AE: Liver fibrosis, lung toxicity, lymphoma.

Anti‑TNF mechanism+Ex+AE

Block TNF‑α → ↓ inflammation; close fistulas. ex: Infliximab(Remicade). AE: reactivated infection with TB, Hep B; lymphoma

Anti‑integrin agent+mechanism+AE

Vedolizumab. Blocks α4β7 integrin → inhibits leukocyte adhesion and migration into intestinal submucosa (therefore less inflammatory response). AE: Possible PML (rare), infections.

Anti‑IL‑12/23 agent=(cytokine inhibitor)+mechanism+AE

Ustekinumab. Blocks p40 subunit of IL‑12/23 → ↓ Th1/Th17 signaling. AE: Infections, Reverse Posterior Leukoencephalopathy Syndrome(headaches and seizures)

Microscopic colitis features+ types+treatment

Chronic watery non‑bloody diarrhea; normal colonoscopy. Types: Lymphocytic colitis; collagenous colitis. Treatment: Loperamide; budesonide.

Diversion colitis cause + treatment

Colon excluded from fecal stream → Short fatty acid chain(SCFA) deficiency. Treat: Restore bowel continuity; SCFA enemas.

Glucocorticoid mechanism (prednisone) + AE

General immunosuppression; ↓ cytokines; ↓ leukocyte migration. AE: Hyperglycemia, hypertension, osteoporosis, psychosis, adrenal suppression.

Budesonide mechanism+use+AE

High first‑pass metabolism → fewer systemic effects, locally suppresses mucousal T cell activity;Mild ileocecal Crohn’s; mild UC (Uceris); AE: dec risk of steriod side effects (Buds suppress their mucous T)