GI Pharmacology: Intro

Question 1

What is the effect of the SNS on the GI walls, sphincters, and secretions?

Answer 1

Walls: Relaxes via alpha-2, beta-2
Sphincters: Contracts via alpha-1
Secretions: No effect

Question 2

What is the effect of the PNS on the GI walls, sphincters, and secretions?

Answer 2

Walls: contracts via M-3
Sphincters: Relaxes via M-3
Secretions: Increases via M-3

Question 3

What is the predominant tone in the GI tract?

Answer 3

Parasympathetic (cholinergic)

Question 4

What are the effects of cholinergic agonism?

Answer 4

Diarrhea
Urination
Miosis/muscle weakness
Bronchorrhea
Bradycardia
Emesis
Lacrimation
Salivation/sweating

Question 5

What are the component parts of the Enteric nervous system?

Answer 5

The Myenteric plexus (Aurbachs’s): controls the smooth muscle in the GI wall

Meissner’s Plexus: Found in the sub-mucosa, It controls the secretion and neuroimmune aspects of the GI tract

Question 6

What is the role of Dopamine in the enteric nervous system?

Answer 6

Dopamine is a modulatory transmitter in the ENS

Question 7

What is the function of Enkephalins in the ENS?

Answer 7

They inhibit Ach release and peristalsis

they MAY stimulate secretion.

Question 8

What is the function of Serotonin (5-HT) in the ENS?

Answer 8

Serotonin is an important Neurotransmitter/co-transmitter at excitatory neuron-neuron junctions in the ENS.

Question 9

What are some sub-types of IBS?

Answer 9

D-IBS: diarrhea predominant

C-IBS: Constipation predominant

Question 10

What are some pharmacologically important causes of IBS?

Answer 10

Excess 5-HT release –> D-IBS

Insufficient release of 5-HT –> C-IBS

Question 11

What is the underlying cause of IBS?

Answer 11

Alteration of normal microbiota and the bodies reaction to these organisms

Question 12

What are the predominant symptoms of IBS?

Answer 12

IBS usually involves periods of constipation and diarrhea along with abdominal pain and discomfort.

Question 13

What are the pharmocologic treatments for IBS (generally speaking)?

Answer 13

Stool softeners: laxatives, lubiprostone
Anti-diarrheal agents: Alosetron
Anti-spasmodics: Dicylomine, Hyoscyamine,ppt oil
TCAs:Amitrytyline, Desipramine, Doxepin
SSRIs: Fluoxetine, Paroxetine, Citalopram

Question 14

Are Probiotics effective in management of IBS?

Answer 14

Lactobacillus and Bifidobacterium are the most common probiotics used. They improve barrier function, acidify colon, and improve dysmotility. However, they are not highly effective.

Question 15

What are the effects of Acupuncture, herbal medicine, and psychology on IBS?

Answer 15

Acupuncture and Psychology appear to have no benefit on IBS.

However, Herbal medicines have shown some promise but the evidence is still too weak.

Question 16

What is IBD?

Answer 16

IBD is an umbrella term for diseases like ulcerative colitis and Crohn’s disease.
Microbe sensing dysfunction (Crohn’s disease)
Disruption of physical barrier (ulcerative colitis)
Immune dysregulation

Question 17

What cytokine is very important in IBD?

Answer 17

TNF-alpha

Question 18

What targeted drugs are useful in treating IBD?

Answer 18

Anti-TNF-alpha Mabs
Infliximab
Adalimumab
Gorlimumab
Certolizumab pegol

Question 19

What are the recommendations for using TNF-alpha

MABs for Crohn’s disease?

Answer 19

Used as alternatives to steroids in patients who have failed treatment. Or for maintenance of remission.

Question 20

What are the recommendations for using Infliximab to treat ulcerative colitis?

Answer 20

Used for patients that are refractory to or unable to take glucocoticoids. Again used in severe cases where treatment has failed.