Pharmacology Flashcards
1
Q
Mucus cells secrete what?
A
Mucus and bicarbonate
2
Q
Parietal cells secrete what?
A
Hydrochloric acid
3
Q
Enterochoromaffin like cells secrete what?
A
Histamine
4
Q
G cells secrete what?
A
Gastrin
5
Q
D cells secrete what?
A
Somatostatin
6
Q
Chief cells secrete what?
A
Pepsinogen
7
Q
HCl secretion from gastric parietal cells includes which 4 channels?
A
- chloride bicarbonate exchanger
- chloride potassium symporter
- H+/K+ ATPase (proton pump)
- carbonic anhydrase
8
Q
Describe the action of histamine
A
- secreted by the enterochromaffin-like cells in the gastric glands in response to stimulation by ACh
- histamine binds to H2 receptors with subsequent activation of adenylyl cyclase
- the increase in cAMP increases the number of proton pumps, increasing gastric acid secretion from parietal cells
9
Q
Describe the action of ACh
A
- released by parasympathetic cholinergic neurons
- ACh binds to muscarinic ACh receptors on parietal cells with subsequent activation of PLC
- the increase in intracellular Ca2+ evokes cell signalling pathways that increase the number of proton pumps, increasing gastric acid secretion from parietal cells
10
Q
Describe the action of gastrin
A
- released by G cells
- gastrin binds to CCK2 receptors on parietal cells with subsequent activation of PLC
- the increase in intra cellular Ca2+ increases the number of proton pumps, increasing gastric acid secretion from parietal cells
11
Q
Describe the action of somatostatin
A
- secreted by D cells in the gastric glands
- binds to SST2R receptors, inhibiting adenylyl cyclase
- the decrease in cAMP results in decreased gastric acid secretion from parietal cells
- somatostatin binding to SST2R receptors on enterochromaffin cells results in reduced histamine release and decreased gastric acid secretion from parietal cells
12
Q
Mechanism of action of antacids
A
Reduce the symptoms of excessive gastric acid secretion by buffering HCl
13
Q
Mechanism of action of NSAIDs
A
- disrupt the production of prostaglandins by inhibiting COX-1
- the reduced availability of prostaglandins results in histamine secretion from enterochromaffin like cells, promoting HCl secretion from parietal cells
14
Q
What drug is an analogue of prostaglandin E1?
A
Misoprostol
15
Q
Describe the features of misoprostol
A
- indicated for prophylaxis of NSAID induced peptic ulcers
- side effects; abdominal pain and diarrhoea
- also induces labour
16
Q
Name some proton pump inhibitors
A
- lansoprazole
- omeprazole
- pantoprazole
17
Q
Describe the mechanism of action of proton pump inhibitors
A
- irreversibly inhibit H+/K+ ATPase pump which reduced HCl secretion
- indicated for benign gastric acid ulceration and NSAID-associated gastric ulceration, gastro-oesophageal reflux disease and Zollinger-Ellison syndrome
18
Q
Side effects of proton pump inhibitors
A
- increased stomach pH reduces defences against infection via the GI tract
19
Q
Name some histamine H2 receptor antagonists
A
- ranitidine
- cimetidine
- famotidine
- nizatidine
20
Q
Mechanism of action of histamine H2 receptor antagonists
A
- blocking the H2 receptor eventually reduces HCl secretion
- complete block of H2 receptors results in a rapid effect
- indicated for benign gastric acid ulceration and NSAID-associated gastric ulceration
21
Q
How do you eradicate h. pylori infection?
A
PPIs + antibiotics (clarithromycin and amoxicillin or metronidazole)
22
Q
Nausea and vomiting may be attributed to what?
A
- anxiety
- motion sickness
- migraine
- pregnancy
- side effects of drugs
23
Q
Vomiting is a defence mechanism triggered by what?
A
The vomiting / emetic centre located in the brain stem
24
Q
Name the chemoreceptor trigger zone
A
- 5HT3Rs
- D2Rs
25
Name the main neurotransmitter systems involved in nausea / vomiting
5-HT, dopamine and Ach
26
What are the three categories of anti-emetic drugs?
- antihistamines (H1 receptor antagonists)
- antimuscarinics (muscarinic acetylcholine receptor antagonists)
- 5-HT3 receptor antagonists
27
Name some antihistamines (H1 receptor antagonists)
- cyclizine
- promethazine
- diphenhydramine
28
Name some antimuscarinics (muscarinic acetylcholine receptor antagonists)
- scopolamine (hyoscine)
29
Name some 5-HT3 receptor antagonists
- ondansetron
- granisetron
- palonosetron
30
Name the two categories of anti-emetic drugs
- dopamine receptor antagonists
| - neurokinin-1 receptor antagonists
31
Name some dopamine receptor antagonists
- chlorpromazine
- droperidol
- haloperidol
- prochlorperazine
- metoclopramide
32
Name some neurokinin-1 receptor antagonists
- fosaprepitant
| - apreptant
33
Mechanism of action of antihistamine (H1 receptor antagonists)
- act primarily as antagonists at histamine H1 receptors in the brain
- indicated for nausea and vomiting > motion sickness
34
Name side effects of antihistamine (H1 receptor antagonists)
- sedation as they action at H1 receptors in the brain
35
Mechanism of action of antimuscarinics (muscarinic ACh receptor antagonists)
Act primarily as antagonist at muscarinic ACh M1 receptors in the brain. Indicated for motion sickness
36
Name side effect of antimuscarinics
- dry mouth
- tachycardia
- constipation
37
Mechanism of action of 5-HT3 receptor antagonists
Act primarily as antagonists at 5-HT3 receptors in the chemoreceptor trigger zone of the medulla in the hindbrain and also the 5-HT3 receptors in the GI tract
38
Name side effects of 5-HT3 receptor antagonists
- constipation
- diarrhoea
- headache
39
Mechanism of action of dopamine receptor antagonists
Act primarily as antagonists at D2 receptors in the chemoreceptor trigger zone of the medulla in the hindbrain (except domperidone) and also the D2 receptors in the GI tract
40
Name side effects of dopamine receptor antagonists
- diarrhoea
| - extrapyramidal side effects (except domperidone)
41
Mechanism of action of neurokinin-1 receptor antagonists
Act primarily as antagonists at NK1 receptors in the GI tract and the chemoreceptor trigger zone of the medulla in the hindbrain blocking the effects of substance P (which evokes vomiting)
42
Name side effects of neurokinin-1 receptor antagonists
- constipation
| - headache
43
Name the two categories of drugs that affect GI motility
- anti-diarrhoeal drugs
| - laxatives
44
Name some anti-diarrhoeal drugs
- loperamide
| - diphenoxylate
45
Name some laxatives
- ispaghula husk
- senna
- lactulose
46
Describe anti-diarrhoeal drugs
- electrolyte replacements
- loperamide and diphenoxylate are opiates (binds to u-opiate receptors) that has reduced effect on the brain
- sometimes combined with atropine (muscarinic Ach receptor antagonist)
- high doses of loperamide have been associated with drug abuse
47
Name side effects of anti-diarrhoeal drugs
- constipation
- sedation
- respiratory depression
48
Mechanism of action of ispaghula husk
Bulk forming laxative
49
Mechanism of action of lactulose
Osmotic laxative >> hepatic
50
Mechanism of action of senna
Stimulant purgative, increases electrolyte / water secretion
