E4: GI Drugs

Question 1

What are some common conditions of the GI tract?

Answer 1

1. Constipation
2. Diarrhea
3. Nausea/vomiting
4. Peptic Ulcers
5. IBS
6. IBD

Question 2

What is the treatment strategy for constipation?

Answer 2

1. Non-pharmacological lifestyle adjustments to be made first;
   
   1. Increase dietary fiber
   2. Increase water intake
   3. Increase aerobic exercise (promoting bowel propulsion)
2. Choice of laxative is based on severity of symptoms and desired time course of relief
   
   1. In most cases avoid the use of stimulant and secretory laxatives
   2. Try to minimize the risk induction of cycles of diarrhea and rebound constipation, or the development of patient “dependence” on stimulant laxatives

Question 3

What is the treatment strategy for Diarrhea?

Answer 3

Treatment strategy for Diarrhea:

Pharmaceuticals:

• Bulk-forming agents
  
  • Psyllium (i.e. Metamucil)
  • Methylcellulose (i.e. Citrucel)
• Bismuth containing agents
  
  • Bismuth Subsalicylate (i.e. Peptobismol)
• Opioid Agonists
  
  • Loperamide (Imodium)
  • Diphenoxylate (i.e. combined w/ Atropine in Lomotil)
• Somatostatin analogs
  
  • Otreotide (Sandostatin) (For idiopathic severe diarrhea)
• Antimuscarincs
  
  • Dicyclomine (i.e. Bentyl)

NOTE – many times, uncomplicated diarrhea is self-limiting, and resolves in 48-72 hours without treatment

Question 4

What are the symptoms of Irritable Bowel Syndrome (IBS)?

Treatment Strategy?

Answer 4

Symptoms may be explained by disordered colonic motility

• Constipation: Increased segmental (or decreased propulsive?) peristalsis
• Diarrhea: Increased propulsive (or decreased segmental?) peristalsis
• Abnormal small bowel motility also described
• Absence of other GI disease
• Sporadic, unpredictable; often worse with stress
• Constipation, diarrhea, or alternating constipation/diarrhea, often accompanied by abdominal pain/discomfort

Treatment Strategy

1. First, dietary and probiotic approaches should be considered…
2. Pharmaceuticals:

• Antispasmodics
• Tricyclic or SSRI antidepressants
• Bulk forming laxatives
• Antimotility agents
• 5-HT3 antagonists or 5-HT4 agonists

Question 5

Describe a Prokinetic Agent.

What is it used for?

Side effects?

Answer 5

Metoclopramide

Used for;

• Anti-reflux
• Diabetic gastroparesis
• Post-operative gastroparesis
• Predominantly UGI dopaminergic stimulation; little effect on LGI
• Also used as anti-emetic (central & peripheral effects)

Side effects:

Drowsiness

Tardive dyskinesia (uncommon)

Question 6

What are the (2) GI Acid-related diseases described?

Answer 6

Peptic Ulcer Disease (PUD):

• Common source of morbidity
• Major advances in therapy
• Newer knowledge of pathogenesis
• Potential association with malignancy

GastroEsophageal Reflux Disease (GERD):

• Even more common source of morbidity
• Major advances in therapy
• Pathogenesis still not entirely understood
• Predisposes to malignancy