Gastrointestinal Pharmacology Flashcards
(129 cards)
1
Q
What can excess acid secretion lead to?
A
Ulceration of mucosa
2
Q
List the drug types which can help reduce acid secretion in the GIT.
A
Antacids
H2 receptor (histamine) antagonists
PPI’s
3
Q
List some drugs which can affect motility in the GIT.
A
Anti-emetics
Anti-muscarinic
Anti-spasmodic
Anti-molility
4
Q
List some drugs that can be used in treatment of IBD.
A
Corticosteroids
Immunosuppressants
Aminosalicyclates
Biologics
5
Q
List some drugs which can affect the biliary secretions.
A
Bile acid sequestrants
Ursodeoxycholic acid
6
Q
Name the two plexus’ of the enteric NS.
A
Myenteric plexus
Submucosal plexus
7
Q
Where would you find the myenteric plexus?
A
Between the circular muscle layer and longitudal muscle layer
8
Q
Where would you find the submucosal plexus?
A
Between the circular muscle layer and the submucosa
9
Q
Where do the two plexuses of the enteric NS receive their pre-ganglionic parasympathetic fibres from?
A
Vagus nerve
10
Q
What do the pre-ganglionic parasympathetic fibres for the enteric NS cause to happen?
A
Mostly excitatory so increase muscle contraction
11
Q
What is the main neurotransmitter for the pre-ganglionic parasympathetic fibres of the ENS?
A
Acetylcholine
->substance P is also released and has a similar excitatory response.
12
Q
What do acetylcholine Vasoactive intestinal peptide do?
A
Excitatory neurotransmitters which evoke secretion from intestinal crypts.
13
Q
Are the parasympathetic fibres in the ENS mainly preganglionic or postganglionic?
A
Preganglionic
14
Q
Are the sympathetic fibres in the ENS mainly preganglionic or postganglionic?
A
Postganglionic
15
Q
Do the parasympathetic nerve fibres inhibit or stimulate the nerve plexuses of the GIT?
A
Stimulate
16
Q
Do the sympathetic nerve fibres inhibit or stimulate the nerve plexuses of the GIT?
A
Inhibit
17
Q
What role do sensory neurons play in the ENS?
A
Form part of the reflex pathways which respond to mucosal stroking and distension.
This means that they contract muscle above the bolus and relax muscle underneath to allow bolus to move through the GIT.
18
Q
Which paracrine cells are released from cells throughout the GIT and act on nearby cells and have an important role in regulation of acid secretion?
A
Histamine
Somatostatin
19
Q
Which receptors does gastrin bind to?
A
CCK2 receptors
20
Q
What happens when gastrin binds to CCK2 receptors?
A
Mobilisation and exocytosis of histamine
21
Q
Which type of receptor is CCK2?
A
G-protein coupled receptor
22
Q
Which receptors can histamine bind to and which one specifically in related to the GIT?
A
H1- allergy related
H2- GI related
23
Q
Which type of receptor is H2?
A
G-protein coupled receptor
24
Q
What happens when histamine binds to the H2 receptor?
A
Increase in cAMP which then promotes gastric acid secretion.
25
What is the function of the membrane folds called canaliculi?
Increase surface area available for the secretion.
26
Vagal stimulation releases acetylcholine. What will acetylcholine bind to?
M3 receptors
27
As well as binding to M3, what can acetylcholine cause the release of?
Histamine
28
List some conditions which can cause damage to the GIT because of acid secretion.
Barrett's oesophagus
GORD
Peptic ulcer disease
29
Physiologically, what causes reflux problems?
1. Abnormalities in the neural or myogenic control of lower oesophageal sphincter
2. High abdominal pressure due to lesions which occupy space
30
Given some examples of space-occupying-lesions which can lead to high abdominal pressure which can cause reflux.
Tumours
Ascites fluid
Pregnancy- baby taking up space
31
Which prostaglandins inhibit the production of acid and increase mucous secretion?
Prostaglandin E2 and I2
->if there is not the correct balance between the release of acid and mucous, damage and ulceration might occur.
32
How can nitric oxide help with ulceration?
Promotes healing blood flow to areas of ulceration
33
As well as acid production, what else can cause damage to the gut mucosa?
H.pylori infection
34
How can H.pylori cause damage to the mucosa?
Organism causes inflammation putting epithelial cells in direct contact with acid
35
What should be tested for in those with GORD or ulceration?
Test for H.pylori
36
What is the treatment if the patient is positive for H.pylori?
Triple therapy- PPI and 2 antibacterials
37
Which antibacterials should be given in the treatment of H.hylori infections?
Amoxicillin and metronidazole/clarithromycin
38
What do PPI's do?
Reduce the secretion of gastric acid
39
What is the treatment for GORD or ulceration if the patient is negative for H.pylori?
Acid suppression using -
-Antacids
-Alginates
May want to use PPI's or H2-receptor antagonists
Other mucosal protectors
40
Give an example of a common alginate that can be purchased over the counter.
Gaviscon
41
How do antacids and alginates help with acid suppression?
Neutralise acid
42
What can happen if over the counter medication for acid suppression is used excessively?
May be masking something more serious.
May get excess rebound acid production when stopping taking the medication.
43
What is Sucralfate ?
Medication which is used in treatment against ulcers
44
How does Sucralfate work?
In an acidic environment, it hydrolyses and turns into a thick paste which coats the mucosa.
45
Name some of the mucosal protecting drugs.
Sucralfate
Bismuth
Misoprostol
46
Give an example of a H2 receptor antagonist.
Ranitidine
47
What is the mechanism of action for Ranitidine?
Blocks histamine receptors and blocks acid secretion
48
When may H2 receptor antagonists, like Ranitidine be given?
GORD
Peptic Ulcer Disease
49
Give an example of a PPI.
Omeprazole
50
What is the mechanism of action for PPI's, like omeprazole?
Irreversible inhibitor of the proton pump
51
When may PPI's, like omeprazole, be given?
GORD
Peptic Ulcer Disease
52
What are some of the adverse effects of PPI's, like omeprazole?
More likely to have C.difficile infection
B12 deficiency
ECL tumours
AIN (type of kidney disease)
53
Describe the reaction of vomiting.
Defensive reaction to get rid of toxic or irritant components of the gut
54
Describe the motor involvement of the gut in vomiting.
Contraction of diaphragm and abdominal muscles to squeeze the stomach
55
Describe the autonomic activity during the process of vomiting.
Increased salivation
Relaxation of smooth muscle and superior end of GIT, and contraction at inferior end to create pressure gradient to push vomit up!
56
Where in the brain is the vomiting centre?
Medulla
57
What does the vomiting centre in the medulla do?
Receives input from chemoreceptor trigger zone which detects toxins in the blood
58
Why might you be sick after being dizzy?
Being dizzy creates the same affects as being poisoned so if dizzy, the brain thinks that there is poison that the body needs to eject, hence the vomiting
59
Which system is reliable for the whole vomiting while dizzy thing?
Vestibular system
60
Which receptors is the Vestibular system mediated by?
Muscarinic receptors
H1 receptors
61
What can activation of NK1 and CB1 receptors cause to happen?
Vomiting
62
Which receptors are associated with the integration of signalling within the medulla?
D2 receptor
M1 receptor
63
When may you give a NK1 antagonist?
Late phase of cytotoxic emesis (nausea and vomiting caused by chemo or radiotherapy).
64
When may you give CB1 drugs?
If patient has cytotoxic drugs
65
USEFUL
Look at the slide on the powerpoint when going over drugs so you can visualize what is happening pls xx
66
When may you give H1 receptor antagonist drugs?
Motion sickness
67
When may you give anti-muscurinic drugs?
Motion sickness
68
When may you give a D2 (dopamine) antagonist?
During pregnancy
69
When may you give 5-HT receptor antagonist drugs?
Cytotoxic drugs
Post surgery
Radiation
70
What are some side effects of D2 (dopamine) receptor antagonists?
Sedation
Movement
Prolactin release
gal idk either, this is what she put on the slide and did not explain
71
What are some of the side effects of CB1 drugs?
Drowsiness
Dizziness
Dry mouth
Triple D idk
72
What are some of the side effects of anti-muscarinic drugs?
Dry mouth
Blurred vision
73
It can be difficult to treat nausea, but which drugs can work?
Low dose antidepressants, especially tricyclics
74
Which groups of drugs can be used in the treatment of constipation?
Purgatives
Agents that increase drug motility as aim of treatment is to move food through the gut more quickly
75
Which groups of drugs can be used in treatment of diarrhoea?
Anti-diarrhoeal drugs- agents that slow down transit of food through the gut
Anti-spasmodic drugs which decrease smooth muscle tone
76
What do bulk and osmotic laxatives do?
Increase volume and water content of stools
77
Give an example of a bulk laxative.
Methylcellulose
->might be worth remembering that cellulose is associated with fibre
78
What is the mechanism of action for osmotic laxatives?
They contain poorly-absorbed solutes that increase the osmotic load of the gut contents, drawing water into the stool.
79
What are the pros and cons of bulk laxatives.
No adverse effects
Take a few days to work
80
What are the pros and cons of osmotic laxatives?
Quick to work
May cause electrolyte disturbances.
81
Give an example of a faecal softener.
Docusate sodium
82
What do stimulant purgatives/laxatives do?
Increase electrolyte secretion by gut mucosa
83
What are some side effects of stimulant purgatives/laxatives?
Cramping
84
When are stimulant purgatives/laxatives contraindicated?
In cases of bowel obstruction.
85
Given an example of a stimulant purgative/laxative which is taken orally.
Sodium picosulphate
86
Give an example of a stimulant purgative/laxative which is taken suppository*.
*cone placed, usually up bottom. It dissolves to release mediciation
Biscodyl
87
How does domperidone, a type of D2 antagonist, affect motility?
Increases motility
This is because it increases lower oesophageal sphincter pressure, increasing gastric emptying and duodenal peristalsis.
88
How does metraclopramide affect motility?
Increases motility.
Increases gastric motility and emptying.
89
Which types of drugs reduce motility?
Anti-diarrhoeal
90
List some of the drug groups used in the treatment of diarrhoea.
Anti-infective drugs
Anti-diarrhoeal drugs
Anti-spasmatic drugs
91
Which type of drug is often used to reduce motility?
Opiates e.g. loperamide
92
Describe the treatment of IBS
Symptomatic treatment, may include anti-motility agents, antidepressants.
High residue diet, lots of fibre
93
Which type of drug are used in the treatment of flare ups of IBD?
Corticosteroids, usually prednisolone
94
What are some of the side effects of corticosteroids?
Osteoporosis
Cushingoid symptoms (moon-face appearance).
Thinning of skin
Increased risk of infection
95
Which drugs are usually used in the treatment of chronic IBD?
Aminosalicyclates
96
Give some examples of aminosalicyclates.
Mesalazine
Olsalazine
97
What are some of the adverse effects of aminosalicyclates?
GI upset
Renal impairment
Blood dyscrasias
98
Give some examples of immunosuppressants that can be used in the treatment of IBD.
Azathioprine
Cyclosporin
56-mercaptopurine.
99
Describe the mechanism of action of immunosuppressants
Prevents the formation of purines which are required for DNA synthesis so reduces immune cell proliferation
100
What are some of the adverse effects of immunosuppressants like azathioprine, cyclosporin, etc.?
Targets any rapidly dividing cells.
May cause bone marrow suppression
Organ damage. lungs, liver
Pancreatitis due to pancreatic damage
101
Why are biologics only used for severe cases of CD?
Expensive
Blocks body's response to infection
102
What are some of the adverse effects of biologics?
Higher risk of infection
Infusion reaction causing fever and itch
Anaemia
Malignancy
103
When can anti-spasmatic drugs be used?
Treatment of diarrhoea e.g. IBS
104
Which receptors can acetylcholine bind to to cause smooth muscle contraction?
M2
M3
105
What do antimuscarinic drugs do?
Inhibit the binding of acetylcholine to M2/M3 causing muscle relaxation and reduces spasm
106
Give an example of a antimuscarinic.
Buscopan
107
Which natural oil is an antimuscarinic?
Peppermint oil
108
How does peppermint oil act as an antimuscarinic?
Contains calcium channel blockers which reduce calcium required for smooth muscle contraction
109
What is the preferred treatment for gallstones?
Surgery
110
Which drugs can be used to dissolve gallstones?
Usodeoxycholic acid
111
How do bile acid sequestrants, like cholestyramine, lower cholesterol levels?
Cholesterol gets converted into bile acids, which are then excreted in bile. Bile acids sequestrants hold the bile in the gut, hence lowering cholesterol levels.
112
What is one disadvantage of bile acid sequestrants?
May interfere with vitamin absorption
113
How do a lot of drugs get distributed around the body?
Bind to plasma proteins
114
Why may liver disease effect the distribution of drugs?
Less albumin in liver disease, affecting protein binding
115
Where is the main site of drug metabolism?
Liver
116
What is the effect of damaged gut wall in metabolism of drugs?
Less first-pass metabolism
117
How can GI disease affect absorption of drugs?
pH
Gut length
Transit time
118
What happens if drugs are excreted via the biliary system?
Drugs may build up
119
What may happen to the liver due to the metabolism of drugs primarily taking place here?
May accumulate and have a hepatotoxic effect
120
Which receptors do NSAIDs block?
COX1, COX2
121
What are the adverse effects of NSAIDs?
Can cause mucosa bleeding
122
How does inhibition of COX1 cause bleeding?
Reduced mucus and bicarbonate secretion
Reduced mucosa blood flow
Impaired platelet aggregation
All of this causes impaired defence and can lead to mucosa damage and bleeding
123
How does inhibition of COX2 cause bleeding
Reduced angiogenesis causing impaired healing
Activation of leukocytes due to leukocyte adhesion.
Both cause mucosal damage and bleeding
124
Which drug may cause acute hepatitis?
Paracetamol
Isoniazid
Ritonavir
Troglotazone
125
Which drug may cause chronic hepatitis?
Diclofenec
Methyldopa
Minocycline
Nitrofurantoin
126
Which drug may cause acute cholestasis?
ACEi
Co-amoxiclav
Chlorpromazine
Erythromycins
127
Which drug may cause fibrosis or cirrhosis?
Methotrexate
128
Which drug may cause NAFLD?
Amiodarone
Tamoxifen
129
