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Yr 3 - Pharmacology > Drugs - GI > Flashcards

Drugs - GI Flashcards

1
Q

Give some potential side effects of laxatives

A
  • Bloating
  • Flatulence
  • Diarrhoea
  • Abdominal discomfort
  • Electrolyte imbalance
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2
Q

What are the 3 main types of laxatives?

A
  1. Stimulant
  2. Bulk forming
  3. Osmotic
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3
Q

What type of laxatives are ‘bran’, ‘ispaghula husk (Fybogel) and ‘methylcellulose’?

A

Bulk-forming laxatives

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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

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5
Q

What is the mechanism behind bulk forming laxatives?

A

Increase faecal mass to stimulate peristalsis

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6
Q

Give the onset of action of bulk-forming laxatives?

A

Up to 72 hours

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7
Q

What must be ensured when prescribing bulk-forming laxatives in order to avoid intestinal obstruction?

A

Adequate fluid intake

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8
Q

What type of laxative is ‘senna’?

A

Stimulant

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9
Q

Onset of action of stimulant laxatives?

A

8-12 hours

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10
Q

Which type of laxative is contraindicated in intestinal obstruction?

A

Stimulant laxatives

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11
Q

What should be used for management short-term occasional constipation ?

A

Dietary & lifestyle changes for relieving short-term occasional constipation

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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

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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

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14
Q

What type of laxatives are ‘lactulose’ and ‘macrogols (laxido)’ examples of?

A

Osmotic laxatives

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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.

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16
Q

Onset for action for osmotic laxatives?

A

2-3 days

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17
Q

What is the most frequently used anti-diarrhoeal?

A

Loperamide (e.g. Immodium)

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18
Q

Give the mechanism of action of senna

A

Stimulates peristalsis, increasing the mobility of the large intestine

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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
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20
Q

What are potential side effects of large doses of loperamide?

A

CVS events e.g. fast/irregular heartbeat

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21
Q

Contraindications of loperamide?

A
  • An active flare up of IBD e.g. ulcerative colitis
  • Antibiotic associated colitis
  • Abdominal distension
  • Constipation
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22
Q

Common side effects of loperamide?

A
  • Constipation
  • Headache
  • Flatulence
  • Feeling dizzy
  • Nausea
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23
Q

Why are anti-diarrhoeals contraindicated in acute ulcerative colitis?

A

as they can increase the risk of toxic megacolon.

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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.

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25
Q

Main cause of toxic megacolon?

A

IBD

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26
Q

What type of drug is mesalazine** & sulphas_alazine_**?

A

Aminosalicylates (5-ASAs)

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27
Q

What is the main indication for aminosalicylates?

A

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
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28
Q

Are aminosalicylates more effective in Crohn’s or UC?

A

Ulcerative Colitis

5-ASAs are an effective treatment option for Ulcerative Colitis. While 5-ASAs may help flare-ups of mild Crohn’s 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.

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29
Q

Mechanism of action of mesalazine?

A

Reduce inflammation of the bowel wall by preventing leucocyte recruitment into the bowel wall and inhibiting the chemotactic response to leukotriene B4.

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30
Q

Potential side effects of mesalazine?

A
  • Nausea, vomiting, and watery diarrhoea
  • Headache and indigestion
  • Mild allergic reactions with rash, itchiness and fever
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31
Q

Contraindications for 5-ASAs?

A
  • Hypersensitivity
  • Severe renal or hepatic impairment
  • Urinary tract obstruction
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32
Q

What is the most common example of an antacid?

A

Gaviscon (alginic acid)

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33
Q

What is the active ingredient in gaviscon?

A

Sodium alginate

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34
Q

Indications for antacids?

A
  • Mild symptoms of dyspepsia
  • Indigestion
  • Heartburn/acid reflux (non-erosive GORD) - relieves symptoms but does not help heal
  • Stomach ulcer
  • Gastritis
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35
Q

Mechanism of action of Gaviscon?

A

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
Q

When is Gaviscon normally taken?

A

After meals and before bedtime

37
Q

Side effects of Gaviscon?

A

Most people will experience no side effects.

  • GI upset
  • Flatulence
  • N&V
  • ANAPHYLAXIS
38
Q

In which type of diets are antacids contraindicated?

A

In diets which should be sodium or calcium restricted.

39
Q

Antacids can be taken in combination with alginates. What is the purpose of this?

A

Antacids taken in combination with alginates increases viscosity of stomach content and can protect oesophageal mucosa from acid reflux.

40
Q

What is the difference between antacids and alginates?

A

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
Q

What class of drugs are ranitidine & cimedtidine?

A

Histamine H2 receptor antagonists

42
Q

In GI pathology, why are antacids sometimes not useful?

A

Can mask symptoms of more serious underlying condition

43
Q

What are the main indications for ranitidine?

A
  • Peptic ulcer disease
  • GORD
  • Relieve symptoms caused by gastric acid secretion e.g. heartburn
44
Q

Mechanism of action of H2 receptor antagonists?

A

Blocks the action of histamine at the H2 receptor of the parietal cells in the stomach → this decreases gastric acid secretion

45
Q

Which cells are responsible for the production of gastric acid? In which part of the stomach?

A

Acid is secreted by parietal cells in the proximal two thirds (body) of the stomach.

46
Q

What should be ruled out before prescribing H2 receptor antagonists? Why?

A

Gastric cancer → may mask symptoms, so rule out before treatment

47
Q

PPIs vs H2 receptor antagonists;

a) onset
b) duration

A

a) H2 receptor antagonists have quicker onset (15-30 mins)
b) PPIs provide longer lasting relief

48
Q

What class of drug is omeprazole and lansoprazole?

A

Proton pump inhibitors

49
Q

Indications for PPIs?

A

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
Q

Do PPIs help heal the ulcer?

A

Yes

51
Q

Mechanism of PPIs

A

Block the H+/K+ ATPase proton pump of the gastric parietal cell → inhibits gastric acid secretion

52
Q

Contraindications of PPIs?

A

Hepatic insufficiency

Pregnnacy & breastfeeding

53
Q

Which PPI is considered safe in pregnancy and breastfeeding?

A

Omeprazole

54
Q

Give some side effects of PPIs

A

Generally well tolerated

  • GI upset - constipation, diarrhoea, flatulence, abdo pain
  • Headaches
  • N&V
55
Q

Why can PPIs cause a slight increased risk of GI infections (e.g. salmonella, campylobacter)?

A

Due to decreased gastric acidity

56
Q

Indications of antispasmodics?

A

Abdominal pain and spasms - often in IBS

57
Q

Which condition is antispasmodics mainly used for?

A

IBS

58
Q

What are the 2 classes of antispasmodics?

A

a) antimuscarinics (‘anticholinergics’)
b) smooth muscle relaxants

59
Q

Mechanism of antimuscarinics?

A

Block action of ACh which prevents impulses for PNS from reaching smooth muscle and causing contractions/cramps/spasms

60
Q

Mechanism of direct muscle relaxants?

A

relaxes muscles in and around gut

61
Q

Give the 4 main side effects of anticholinergics

A

Can’t see → blurred vision/dry eyes

Can’t pee → urinary retention

Can’t spit → dry mouth

Can’t shit → constipation

62
Q

Contraindications of anticholinergics?

A
  • Paralytic ileus
  • Intestinal obstruction
  • Myasthenia gravis
  • Pyloric stenosis
63
Q

What is the purpose of anti-emetics?

A

Treatment of vomiting & nausea

64
Q

What medications may produce side effects that require anti-emetics to manage? (prescribing cascade)

A
  • Chemotherapy
  • General anaesthetics
  • Opioid analgesics
65
Q

Give 4 main classes of antiemetics

Give an example for each

A
  1. H1 receptor antagonists → cyclizine
  2. D2 receptor antagonists → domperidone, metoclopramide
  3. 5HT3 receptor antagonist → ondansetron
  4. Anti-muscarinic → hyoscine hydrobromide
66
Q

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
A

Ondansetron

67
Q

What class of drug is ondansetron?

A

Anti-emetic (5HT3 receptor antagonist)

68
Q

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
A

Omeprazole, clarithromycin and metronidazole

69
Q

What is the selection of Abx for triple therapy for eradication of H. pylori?

A

The Abx selected for triple therapy are out of amoxicillin (broad spectrum penicillin), clarithromycin (macrolide) and metronidazole

70
Q

If the patient is penicillin allergic, which 2 Abx are used in triple therapy in eradication of H. pylori?

A

Clarithromycin and metronidazole

71
Q

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)
A

Loperamide

It is an anti-motility drug used in selected cases of diarrhoea

72
Q

Mechanism of loperamide? Why dos it no produce CNS effects (e.g. analgesia)?

A

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
Q

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
A

Lactulose

74
Q

Why is lactulose indicated in hepatic encephalopathy (despite the patient being constipated or not)?

A
  • 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
Q

What class of laxative is lactulose?

A

Osmotic

76
Q

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
A

Loratadine orally

77
Q

What is the 1st line pharmacological management in pruritus in liver disease?

A

Antihistamine (loratadine)

78
Q

Why is loratadine preferred over chlorphenamine in pruritus in liver disease? (both antihistamines)

A

Avoid sedating ones where possible as this can precipitate hepatic encephalopathy

  • Loratadine → non-sedating antihistamine
  • Chlorphenamine → sedating antihistamine
79
Q

An 82 y/o woman is advised to take ranitidine for dyspepsia. What is the mechanism of action of ranitidine?

A

Antagonism of histamine H2 receptors in gastric parietal cells

80
Q

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
A

FBC

81
Q

What class of drug is azathioprine?

A

Immunosuppressant

82
Q

What is the most serious dose related adverse effect of azathioprine?

A

bone marrow suppression, which results most significantly in leucopenia and increased risk of infection

83
Q

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?

A

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
Q

Cholestatic jaundice is a rare but serious adverse effect of which Abx?

A

Flucloxacillin

85
Q

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
A

Levothyroxine

86
Q

Why is a 2 hour gap advised between Gaviscon and Levothyroxine?

A
  • 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

Yr 3 - Pharmacology (18 decks)

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