Drugs - GI Flashcards
(86 cards)
1
Q
Give some potential side effects of laxatives
A
- Bloating
- Flatulence
- Diarrhoea
- Abdominal discomfort
- Electrolyte imbalance
2
Q
What are the 3 main types of laxatives?
A
- Stimulant
- Bulk forming
- Osmotic
3
Q
What type of laxatives are ‘bran’, ‘ispaghula husk (Fybogel) and ‘methylcellulose’?
A
Bulk-forming laxatives
4
Q
What type of laxative would be prescribed in adults with small hard stools if fibre cannot be increased in diet (or lifestyle changes are not proving effective)?
A
Bulk-forming
5
Q
What is the mechanism behind bulk forming laxatives?
A
Increase faecal mass to stimulate peristalsis
6
Q
Give the onset of action of bulk-forming laxatives?
A
Up to 72 hours
7
Q
What must be ensured when prescribing bulk-forming laxatives in order to avoid intestinal obstruction?
A
Adequate fluid intake
8
Q
What type of laxative is ‘senna’?
A
Stimulant
9
Q
Onset of action of stimulant laxatives?
A
8-12 hours
10
Q
Which type of laxative is contraindicated in intestinal obstruction?
A
Stimulant laxatives
11
Q
What should be used for management short-term occasional constipation ?
A
Dietary & lifestyle changes for relieving short-term occasional constipation
12
Q
When should stimulant laxatives only be used?
A
Stimulant laxatives should only be used if these measures and other laxatives (bulk-forming and osmotic) are ineffective
13
Q
Why are stimulant laxatives used last despite being more effective?
A
More likely to cause side effects (diarrhoea and GI discomfort) as well as creating dependence
14
Q
What type of laxatives are ‘lactulose’ and ‘macrogols (laxido)’ examples of?
A
Osmotic laxatives
15
Q
Give the mechanism for osmotic laxatives
A
They increase the amount of water in the large bowel by either:
a) drawing fluid into the bowel
b) retaining fluid the fluid they were administered with
This makes stools easier to pass.
16
Q
Onset for action for osmotic laxatives?
A
2-3 days
17
Q
What is the most frequently used anti-diarrhoeal?
A
Loperamide (e.g. Immodium)
18
Q
Give the mechanism of action of senna
A
Stimulates peristalsis, increasing the mobility of the large intestine
19
Q
Give some indications for loperamide
A
- Symptomatic treatment of acute diarrhoea
- Chronic diarrhoea e.g. Crohn’s disease
- Pain of bowel colic in palliative care
20
Q
What are potential side effects of large doses of loperamide?
A
CVS events e.g. fast/irregular heartbeat
21
Q
Contraindications of loperamide?
A
- An active flare up of IBD e.g. ulcerative colitis
- Antibiotic associated colitis
- Abdominal distension
- Constipation
22
Q
Common side effects of loperamide?
A
- Constipation
- Headache
- Flatulence
- Feeling dizzy
- Nausea
23
Q
Why are anti-diarrhoeals contraindicated in acute ulcerative colitis?
A
as they can increase the risk of toxic megacolon.
24
Q
What its toxic megacolon?
A
A life-threatening condition characterised by non-obstructive segmental or pancolonic dilatation of at least 6 cm with systemic toxicity.
25
Main cause of toxic megacolon?
IBD
26
What type of drug is mes**_alazine**_ & sulphas_**alazine_**?
Aminosalicylates (5-ASAs)
27
What is the main indication for aminosalicylates?
IBD - Crohn's disease & ulcerative colitis
* First treatment option for mild to moderate **flare-ups** of Ulcerative Colitis, used to **maintain remission**
* Less often used in management of Crohn’s disease but can be given as first option if condition is mild
28
Are aminosalicylates more effective in Crohn's or UC?
_Ulcerative Colitis_
5-ASAs are an effective treatment option for [**Ulcerative Colitis**](https://www.crohnsandcolitis.org.uk/about-crohns-and-colitis/publications/ulcerative-colitis)**.** While 5-ASAs may help flare-ups of mild [**Crohn’s Disease**](https://www.crohnsandcolitis.org.uk/about-crohns-and-colitis/publications/crohns-disease), there is little evidence that they are effective in maintaining remission. As there is less evidence of their effectiveness, 5-ASAs are not recommended for **severe** Crohn’s.
29
Mechanism of action of mesalazine?
Reduce inflammation of the bowel wall by **preventing leucocyte recruitment** into the bowel wall and inhibiting the chemotactic response to **leukotriene** **B4**.
30
Potential side effects of mesalazine?
* Nausea, vomiting, and watery diarrhoea
* Headache and indigestion
* Mild allergic reactions with rash, itchiness and fever
31
Contraindications for 5-ASAs?
* Hypersensitivity
* Severe renal or hepatic impairment
* Urinary tract obstruction
32
What is the most common example of an antacid?
Gaviscon (alginic acid)
33
What is the active ingredient in gaviscon?
Sodium alginate
34
Indications for antacids?
* Mild symptoms of dyspepsia
* Indigestion
* Heartburn/acid reflux (non-erosive GORD) - relieves symptoms but does not help heal
* Stomach ulcer
* Gastritis
35
Mechanism of action of Gaviscon?
Contains alkaline ions that **neutralise gastric acid** to relieve pain and discomfort.
Gaviscon reacts with gastric acid to forms a protective barrier (alginic acid - pH 7) over the stomach contents.
36
When is Gaviscon normally taken?
After meals and before bedtime
37
Side effects of Gaviscon?
Most people will experience **no side effects**.
* GI upset
* Flatulence
* N&V
* ANAPHYLAXIS
38
In which type of **diets** are antacids contraindicated?
In diets which should be **sodium** or **calcium** restricted.
39
Antacids can be taken in combination with alginates. What is the purpose of this?
**Antacids** taken in combination with **alginates** increases viscosity of stomach content and can **protect oesophageal mucosa** from acid reflux.
40
What is the difference between antacids and alginates?
Some antacids contain **alginates** → alginates coats your gullet with a protective layer (protecting oesophageal mucosa from acid reflux)
Antacids alone just neutralise stomach acid.
41
What class of drugs are rani**_tidine_** & cimed**_tidine_**?
Histamine H2 receptor antagonists
42
In GI pathology, why are antacids sometimes **not useful**?
Can mask symptoms of more serious underlying condition
43
What are the main indications for ranitidine?
* Peptic ulcer disease
* GORD
* Relieve symptoms caused by gastric acid secretion e.g. heartburn
44
Mechanism of action of H2 receptor antagonists?
Blocks the action of histamine at the **H2 receptor of the parietal cells** in the stomach → this decreases gastric acid secretion
45
Which cells are responsible for the production of gastric acid? In which part of the stomach?
Acid is secreted by parietal cells **in the proximal two thirds (body) of the stomach**.
46
What should be ruled out before prescribing H2 receptor antagonists? Why?
Gastric cancer → may mask symptoms, so rule out before treatment
47
PPIs vs H2 receptor antagonists;
a) onset
b) duration
a) H2 receptor antagonists have quicker onset (15-30 mins)
b) PPIs provide longer lasting relief
48
What class of drug is omeprazole and lansoprazole?
Proton pump inhibitors
49
Indications for PPIs?
Conditions where too much stomach acid is produced:
* GORD
* Peptic ulcers
* Heartburn
* Reflux oesophagitis
To relieve symptoms of:
* Reflux e.g. heartburn
* Ulcers e.g. epigastric pain
Others:
* H. pylori eradication (triple therapy)
* Zollinger-Ellison syndrome (rare)
* Prophylaxis for ulcers
50
Do PPIs help heal the ulcer?
Yes
51
Mechanism of PPIs
Block the **H+/K+ ATPase proton pump** of the gastric parietal cell → inhibits gastric acid secretion
52
Contraindications of PPIs?
Hepatic insufficiency
Pregnnacy & breastfeeding
53
Which PPI is considered safe in pregnancy and breastfeeding?
Omeprazole
54
Give some side effects of PPIs
Generally well tolerated
* GI upset - constipation, diarrhoea, flatulence, abdo pain
* Headaches
* N&V
55
Why can PPIs cause a slight increased risk of GI infections (e.g. salmonella, campylobacter)?
Due to decreased gastric acidity
56
Indications of antispasmodics?
Abdominal pain and spasms - often in **IBS**
57
Which condition is antispasmodics mainly used for?
IBS
58
What are the 2 classes of antispasmodics?
a) antimuscarinics ('anticholinergics')
b) smooth muscle relaxants
59
Mechanism of antimuscarinics?
Block action of ACh which prevents impulses for PNS from reaching smooth muscle and causing contractions/cramps/spasms
60
Mechanism of direct muscle relaxants?
relaxes muscles in and around gut
61
Give the 4 main side effects of anticholinergics
Can't see → blurred vision/dry eyes
Can't pee → urinary retention
Can't spit → dry mouth
Can't shit → constipation
62
Contraindications of anticholinergics?
* Paralytic ileus
* Intestinal obstruction
* Myasthenia gravis
* Pyloric stenosis
63
What is the purpose of anti-emetics?
Treatment of vomiting & nausea
64
What medications may produce side effects that require anti-emetics to manage? (prescribing cascade)
* Chemotherapy
* General anaesthetics
* Opioid analgesics
65
Give 4 main classes of antiemetics
Give an example for each
1. H1 receptor antagonists → cyclizine
2. D2 receptor antagonists → domperidone, metoclopramide
3. 5HT3 receptor antagonist → ondansetron
4. Anti-muscarinic → hyoscine hydrobromide
66
**A 24 y/o woman is vomiting following an evacuation of retained products of conception, performed under general anaesthesia. She was given cyclizine IV 30 minutes ago but this has not improved her symptoms. Her PMH includes a severe illness involving fever and muscle spasms, which was through to have been precipitated by a prochlorperazine injection. What is the most appropriate treatment for her N&V?**
1. **Chlorpromazine**
2. **Cyclizine**
3. **Haloperidol**
4. **Metoclopramide**
5. **Ondansetron**
Ondansetron
67
What class of drug is ondansetron?
Anti-emetic (5HT3 receptor antagonist)
68
**A 48 y/o woman who has peptic ulcers caused by H.pylori infection presents to her GP to commence treatment. She is allergic to benzylpenicillin, which caused an anaphylactic reaction. What is the most appropriate 1-week oral treatment regimen?**
1. **Lansoprazole, amoxicillin and clarithromycin**
2. **Lansoprazole, amoxicillin and metronidazole**
3. **Omeprazole and clarithromycin**
4. **Omeprazole and metronidazole**
5. **Omeprazole, clarithromycin and metronidazole**
Omeprazole, clarithromycin and metronidazole
69
What is the selection of Abx for triple therapy for eradication of H. pylori?
The Abx selected for triple therapy are out of **amoxicillin** (broad spectrum penicillin), **clarithromycin** (macrolide) and **metronidazole**
70
If the patient is penicillin allergic, which 2 Abx are used in triple therapy in eradication of H. pylori?
Clarithromycin and metronidazole
71
**An 86 y/o woman has been taking codeine phosphate to treat a sprained wrist. Co-incidentally, she has noticed that this has improved the diarrhoea she usually suffers due to her diverticular disease. Although her wrist is now healed, she is keen to continue taking the codeine as not having to open her bowels as often. However, the codeine does make her feel lightheaded. What alterative opioid would be better to treat her diarrhoea?**
1. **Loperamide**
2. **Morphine (immediate release)**
3. **Morphine (modified release)**
4. **Oxycodone (modified release)**
Loperamide
## Footnote
It is an **anti-motility** drug used in selected cases of diarrhoea
72
Mechanism of loperamide? Why dos it no produce CNS effects (e.g. analgesia)?
Antimotility effects that are mediated by **opioid receptor agonism** in the **myenteric plexus of the GI tract.**
It is an opioid, similar to pethidine, but **does not cross the BBB** so does not produce CNS effects (analgesia) but retains the peripheral effects such as reducing gut motility
73
**A 62 y/o man with a background of alcoholic cirrhosis is admitted to the acute medical unit with confusion. A diagnosis of hepatic encephalopathy is made. His wife reports that he has been complaining of constipation in the days leading up to admission. What laxative should be prescribed?**
1. **Docusate sodium**
2. **Ispaghula husk**
3. **Lactulose**
4. **Macrogol**
5. **Senna**
Lactulose
74
Why is lactulose indicated in hepatic encephalopathy (despite the patient being constipated or not)?
* One of the main substances involved in the pathogenesis of hepatic encephalopathy is ammonia
* _Lactulose_ is an **osmotic laxative** that **reduces the absorption of ammonia** by increasing the transit rate of colonic contents and by acidifying the stool (this inhibits the proliferation of ammonia-producing bacteria)
75
What class of laxative is lactulose?
Osmotic
76
**A 50 y/o man complains of severe itch. He has had this for several days and it affects his whole body. He was admitted yesterday with progressive ascites as a result of cirrhotic liver disease. He is taking furosemide, spironolactone, lactulose and phosphate enemas. He has no allergies. On examination of the skin, there are multiple spider naevi over his upper body and excoriation marks over his arms, trunk and thighs. What is the most appropriate initial pharmacological treatment?**
1. **Chlorphenamine orally**
2. **Codeine phosphate orally**
3. **Hydrocortisone topically**
4. **Loratadine orally**
5. **Prednisolone orally**
Loratadine orally
77
What is the 1st line pharmacological management in pruritus in liver disease?
Antihistamine (loratadine)
78
Why is loratadine preferred over chlorphenamine in pruritus in liver disease? (both antihistamines)
Avoid sedating ones where possible as this can precipitate hepatic encephalopathy
* Loratadine → non-sedating antihistamine
* Chlorphenamine → sedating antihistamine
79
**An 82 y/o woman is advised to take ranitidine for dyspepsia. What is the mechanism of action of ranitidine?**
Antagonism of histamine H2 receptors in gastric parietal cells
80
**A 55 y/o man is seen in the gastroenterology clinic to discuss the management of his UC. Apart from IBD, he has no other PMH. A decision is made to start azathioprine. What blood tests will he need to have each week in the first month of treatment?**
1. **FBC**
2. **LFTs**
3. **TFTs**
4. **Renal function**
5. **Serum glucose**
FBC
81
What class of drug is azathioprine?
Immunosuppressant
82
What is the most serious dose related adverse effect of azathioprine?
**bone marrow suppression**, which results most significantly in leucopenia and increased risk of infection
83
**A 55 y/o woman with psoriatic arthritis was admitted to hospital 12 days ago with severe cellulitis. On admission, her liver function was normal but she has now developed cholestatic jaundice. Her medications are flucloxacillin, methotrexate, morphine, paracetamol and simvastatin. Which drug is most likely to have caused her jaundice?**
Flucloxacillin
* Cholestatic jaundice is a rare but serious adverse effect of flucloxacillin (penicillinase-resistant penicillin)
* Can occur when treatment has been completed and is a contraindication to future use of this drug
84
Cholestatic jaundice is a rare but serious adverse effect of which Abx?
Flucloxacillin
85
**A 44 y/o man complains of heartburn. His PMH includes asthma, epilepsy and salbutamol. His GP recommends a trial of Gaviscon. What medicine should he be advised to separate from Gaviscon by at least 2 hours?**
1. **Beclomethasone**
2. **Carbamazepine**
3. **Levothyroxine**
4. **Montelukast**
5. **Salbutamol**
Levothyroxine
86
Why is a 2 hour gap advised between Gaviscon and Levothyroxine?
* Gaviscon is a **compound alginate** which also contains the **antacid calcium carbonate**
* The divalent cation (Ca2+) in calcium carbonate can bind to many drugs in the gut and reduce their absorption
* Examples include tetracyclines, digoxin, iron, bisphosphonates and thyroid hormones (levothyroxine)
* A 2 hour gap is advised to minimise this
