IBS IBD

Question 1

define IBS

Answer 1

Iritable bowel syndrome (IBS)

–> IDIOPATHIC CHRONIC RELAPSING DISORDER characterized by abdominal discomfort (PAIN, BLOATING, DISTENSION, or CRAMPS) in association with alteration in bowel habits (DIARRHEA, CONSTIPATION or both)

Question 2

describe tx strategy for iBS

Answer 2

• Aim is at relieving pain and improving bowel function

–> Loperamide = reduce diarrhea

–> osmotic laxatives = releive constipation

–> Relieve pain

–> tricyclic antidepressants

–> antispasmodics/antimuscarinics agents

Question 3

describe the role of tegaserod and alosetron in IBS tx

Answer 3

• Tegaserod = 5-HT4 partial agonist (IBS-constipation predominant)

–> promotes NT release in ENS resulting in motility

–> decrease firing of extrensic sensory neurons to CNS (Block pain)

• Alosetron = 5-HT3 antagonist (IBS-diarrhea predominant)

–> BLOCKS visceral pain, motility and secretions

–> WOMEN ONLY

Question 4

describe the dsieases that make up inflammatory bowel disease (IBD)

Answer 4

• Ulcerative colitis –> affects the large intestine and originates in the crypts of lieberkuhn
• Crohns disease –> can affect any part of the GI tract but is genreally associated with the ileum

–> originates in the intestinal submucosa and eventually spreads to mucosa and serosa (pattern of skip lesions)

Question 5

Sulfasalazine

Answer 5

AMINOSALICYLATES (ASA)

• 1st line agent for mild to moderate ulcerative colitis (40% of patients can’t tolerate it)

–> adverse effects = nausea, GI upset, headache etc

• admin orally –> target colon (works topically)

Question 6

Mesalamine

Answer 6

AMINOSALICYLATES

• 1st line agent for mild to moderate ulcerative colitis

–> much better tolerated (35% = headache, 20% abdominal pain)

• Admi orally –> target throughout intestine, ileum, colon

Question 7

Prednisone

Answer 7

• Glucocorticoid –> supresses inflammation via inhibiting inflammatory cytokines (TNFalpha, IL-1)
• TX for moderate to severe active IBD

Question 8

Azathioprine

Answer 8

• Mech of action = inhibition of purine synthesis resulting in decreased DNA synthesis and repair leading to decreased cell proliferation
• TX for: MAINTENANCE of REMISSION OF IBD
• ADVERSE EFFECTS = nausea, vomiting, bone marrow suppression

Question 9

Methotrexate

Answer 9

• mech of action: innhibits DHFR resulting in impaired cellular proliferation
• TX for: maintenance of remission of Crohn’s (onset 8-12 weeks)
• Adverse effects = low dose side effects uncommong, but include bone marrow depression and megaloblastic anemia

Question 10

Infliximab

Answer 10

• immunoglobulin that binds and sequesters TNFalpha RESULTING in INHBIITION of INFLAMMATORY RESPONSE
• TX for: moderate to severe IBD (not first choice drug)
• ADVERSE EFFECTS = infection (6%)

Question 11

describe the therapeutic strategy with administraiton/drug delivery of aminosalicylates.

Answer 11

• ASA work “TOPICALLY” at the mucosal surface of gastrointestinal tract

–> absorption of agents prior to delivery of drug to the inflamed tissue renders them ineffective

–> therefore, agents must be chemically modified to or packaged to prevent absorption by the gut so as to more effectively reach the target tissue.