Inflammatory Bowel Disease

Inflammatory Bowel Disease is a general term used to describe two chronic inflammatory diseases occurring primarily in the gastrointestinal tract; Ulcerative Colitis and Crohn's Disease

Epidemiology

Ulcerative Colitis and Crohn's disease share many epidemiologic features

1. more common in western societies

2. higher incidence among Jews of Eastern European descent

3. low frequency among non-whites

4. both sexes affected equally

5. usually affect people before the age of 40

6. tend to occur in the same families

7. in Western Canada the prevalence is three times the global one, 150 per 100,000 Vs 50 per 100,000

Etiology

unknown

theories of possible etiology include:

• infectious agents- no causative bacteria has been cultured, bacterial overgrowth seen is probably due to favorable environment rather than relevant to pathogenesis

• genetic factors- the increased frequency in whites, Jews, and family members is suggestive of genetic predisposition, but no genetic marker has been identified.

• immunologic mechanisms
• allergic reaction to cows' milk
• imp aired cellular immune mechanisms
• hypersensitivity reaction
• autoimmune antibody mediated reaction, suggested by extra intestinal manifestations and the fact that treatment with corticosteroids leads to favorable response.

• psychological factors- no proof that stress causes the disease but psychological factors may influence the course of the disease.

1. Incidence of Ulcerative Colitis is static; Crohn's is increasing.
2. Only the colon is affected in Ulcerative Colitis; Crohn's can also affect the small bowel
3. Ulcerative Colitis has a marked tendenct to relapse and remit; Crohn's is similar but less marked.
4. Clinical features of abdominal mass, signs of malabsorption, fistula formation and gross perianal disease do not occur in Ulcerative Cilitis
5. deep Radiological features- Ulcerative Colitis changes affect rectum and proximal colon in continuity; fissuring and aphthoid ulceration, 'skip' lesions and small bowel involvement are features of Crohn's Disease.
6. Histological features- transmural inflammation, fissuring granulomas and goblet cell preservation are features of Crohn's Disease, Ulcerative Colitis is characterized by mucosal inflammation, crypt abscesses and goblet cell depletion.

Treatment goals

1. terminating an acute attack and inducing remission
2. preventing relapse
3. controlling chronic symptoms

DRUGS

Sulfasalazine

- 20 % absorbed

- remainder goes to the colon where colonic bacteria cleave the diazo bond to liberate the 5-ASA

- the sulfapyridine is then absorbed and excreted in the urine

- the 5-ASA molecule remains in the colon where it exerts its actions as local anti-inflammatory

- adverse effects are associated with the sulfapyridine molecule and include nausea, malaise, headache, anorexia, hypersensitivity reaction, vomiting, dyspepsia

Corticosteroids

available in several forms; oral, injectable, enema

considered drugs of choice in the treatment of acute severe attacks and exacerbations

more immediate response than sulfasalazine

Immuno Suppresive Agents

• Azathioprine
• 6-mercaptopurine (6-MP)
• Bacillus Calmette-Guerin (BCG)
• Levamisole
• Transfer factor

not for ulcerative colitis

limited to patients with refractory Crohn's Disease who require high prolonged doses of steroids to control their symptoms and because of the extent of their disease surgery is precluded.

Antimicrobials

no evidence of effectiveness in Ulcerative Colitis

may be effective in some Crohn's patie.ts who fail to respond to Sulfasalazine

Antimotility agents

• Diphenoxylate
• Loperamide
• Codeine Phosphate
• Tincture of opium
• Tincture of belladonna
• Cholestyramine (bile salt binding)
• Hydrophyllic compounds (Psyllium)

Mast cell stabilizers

Investigational drugs

• Nicotine patch
• Leukotriene inhibitors