PHARM - Drugs Used in Gastrointenstinal Disorders - Week 6

Question 1

What two nerves form the parasympathetic innervation to the GI tract? Is it inhibitory, stimulatory, or both?

Answer 1

Craniosacral:
-Vagus nerve
-Pelvic nerve
Stimulatory

Question 2

What nerve form the sympathetic innervation to the GI tract? Is it inhibitory, stimulatory, or both?

Answer 2

Thoracolumbar:
Prevertebral ganglia
Inhibitory

Question 3

Name 8 general causes of vomiting.

Answer 3

Unpleasant smells
Unpleasant sights
Strong emotions
Pain
Headache/migraine
Abnormal motion
Toxins
GIT irritation

Question 4

What 4 signalling molecules are involed in vomiting?

Answer 4

Acetylcholine, dopamine, serotonin, and histamine

Question 5

What kinds of drugs can be used to reduce the urge to vomit based on the signalling molecules involved (4)?

Answer 5

Antihistamines
Dopamine antagonists
Serotonin antagonists
Muscarinic receptor antagonists

Question 6

Name 4 side effects of using a sopamine receptor antagonist.

Answer 6

Increased gastric emptying, restlessness, anxiety, drowsiness

Question 7

Define 5HT3 what kind of nausea 5HT3 receptor antagonists are used for (2).

Answer 7

5HT3 is serotonin
5HT3 receptor antagonists are used to vomiting associated with chemotherapy and post-operative management

Question 8

Do 5HT3 receptor antagonists have few or many antagonists?

Answer 8

Few

Question 9

What form of nausea do antihistamines treat?

Answer 9

Motion sickness induced nausea

Question 10

Name two side effects of antihistamines.

Answer 10

Sedation and drowsiness

Question 11

What form of nausea do muscarinic receptor antagonists treat?

Answer 11

Motion sickness induced nausea

Question 12

Name three side effects of muscarinic receptor antagonists.

Answer 12

Constipation, dry mouth, and tachycardia

Question 13

What two substances do mucous neck cells in the stomach produce?

Answer 13

Mucus and bicarbonate

Question 14

What two substances do parietal cells in the stomach produce?

Answer 14

Gastric acid and intrinsic factor for Ca2+ absorption

Question 15

What substance does enterochromaffin-like cells in the stomach produce and what does it do?

Answer 15

Histamine which stimulates acid

Question 16

What two substances do chief cells in the stomach produce?

Answer 16

Pepsinogen and gastric lipase

Question 17

What substance do D cells in the stomach produce and what does it do?

Answer 17

Somatostatin which inhibits acid

Question 18

What substance do G cells in the stomach produce and what does it do?

Answer 18

Gastrin which stimulates acid

Question 19

Consider the following receptors in the stomach, and whether or not they stimulate or inhibit HCl production:
Histamine receptor
Muscarinic receptor
Gastrin receptor
Somatostatin receptor
Prostaglandin receptor

Answer 19

Histamine receptor - stimulatory
Muscarinic receptor - stimulatory
Gastrin receptor - stimulatory
Somatostatin receptor - inhibitory
Prostaglandin receptor - inhibitory

Question 20

Describe briefly how parietal cells produce HCl.

Answer 20

Is a proton pump that uses ATP to exchange K+ from the lumen for a H+ ion. Once in the lumen, the H+ forms HCl.

Question 21

What can cause oesophagitis.

Answer 21

Acid reflux

Question 22

What causes an oesophageal stricture?

Answer 22

Narrowed tube

Question 23

What three effects do antacids have?

Answer 23

Neutralises HCl, binds bile acid, and decreases pepsin activity.

Question 24

Name 4 general ingredients of antacids.

Answer 24

Aluminium hydroxide
Calcium carbonate
Magnesium salts
Sodium bicarbonate

Question 25

What effect do magnesium and aluminium have on the bowels? Should they be taken apart or together?

Answer 25

Magnesium - increased bowel motility Aluminium - decreased bowel activity They should be taken together

Question 26

What do -tidine drugs (affix) do?

Answer 26

Are histamine receptor antagonists that reduce acid secretion by parietal cells.

Question 27

What do -prazole drugs (affix) do? What kind of environment is required for them to activate? Do they bind reversibly or irreversibly?

Answer 27

Are prodrugs that require activation in an acidic environment. They bind irreversibly to the proton pump of parietal cells.

Question 28

What is an advantage of -prazole drugs?

Answer 28

It will reduce acid secretion independently of how secretions stimulated

Question 29

Are cytoprotective drugs common? What are they and what are they used for?

Answer 29

Prostaglandin analogues that are rarely used. Used to treat ulcers.

Question 30

Name 4 drugs that can directly irritate the oesophagus, cause strictures, and affect acid production.

Answer 30

NSAIDs Bisphosphonates Antibiotics (tetracyclines and doxycycline) Iron supplements

Question 31

What bacteria is a main cause of ulcers? What is it a risk factor for?

Answer 31

Helicobacter pylori Risk factor in the development of gastric carcinoma

Question 32

If an ulcer is caused by H. pylori, what is the first line treatment? What does success depend on?

Answer 32

Eradicating H. pylori Combination therapy of proton pump inhibitors and antibiotics is neccessary Success depends on adherence to the treatment

Question 33

What happens with too little and too much bowel motility?

Answer 33

Too little - constipation Too much - diarrhoea

Question 34

Define constipation and give three possible causes.

Answer 34

Difficult faecal evacuation as a result of hardness or infrequent movements -lifestyle/diet related -medically related -adverse effect from a drug

Question 35

Name 4 agents that can be used to alleviate constipation.

Answer 35

Softeners (coats faeces) Bulk forming agents (psyllium) Stimulants (increased peristalsis) Osmotics (increases lumen fluid volume)

Question 36

What are prokinetics? What kinds of drugs are they?

Answer 36

They are motility stimulating drugs. They are dopamine receptor antagonists.

Question 37

Are opioids motility increasing or decreasing drugs?

Answer 37

Increasing

Question 38

What do anti-spasmodics do?

Answer 38

Smooth muscle relaxant, reducing GI motility and spasm

Question 39

Do antispasmodics cross the blood-brain barrier?

Answer 39

No

Question 40

Are opioids for GI motility used short term or long term? Can they be administered to children?

Answer 40

Short term only Not to be used in children

Question 41

Name three classes of drugs that can be used to treat inflammatory bowel disease.

Answer 41

Corticosteroids 5-aminosalicylates TNF-alpha antagonists They are all anti-inflammatory