Prescribing - Gastroenterology

Question 1

What is Rantidine’s drug class?

Answer 1

H2 receptor antagonist

Question 2

How does Ranitidine work?

Answer 2

reduces stimulation of gastric acid secretion

Question 3

What are common side effects of Ranitidine?

Answer 3

Diarrhoea
Headache
Dizziness

Question 4

When is Ranitidine contraindicated?

Answer 4

Hepatic or renal impairment requires dose reduction
Avoided in Pregnancy
In patients with red flags for gastric cancer- only prescribe if ruled out.

Question 5

What is Cimetidine ?

Answer 5

H2 receptor antagonist

Question 6

What is an important side affect of Cimetidine?

Answer 6

Gynaecomastia

Question 7

What is an absolute contraindication of Cimetidine?

Answer 7

If on Warfrin, theophylline or phenytoin as cimetidine is a Cytochrome P450 inhibitor

Question 8

What is Omeprazole?

Answer 8

A PPI

Question 9

How does Omeprazole work?

Answer 9

inhibits final transport of hydrogen ions into the gastric lumen meaning less acid is secreted

Question 10

What is the follow up for Omeprazole?

Answer 10

Prescribe at lowest effective dose for shortest period of time possible. If needed long term periodic reviews need to be had (every 8 weeks or so)

Magnesium levels need to be monitored

Question 11

What are cautions of PPIs?

Answer 11

PPIs may mask symptoms of gastric cancer – in patients presenting with ‘alarm features’ (bleeding, dysphagia, recurrent vomiting, weight loss) it is important to rule out malignancy before commencing PPI therapy.

Question 12

What drug interactions occur with Omeprazole?

Answer 12

Warfarin - increase anticoagulant effect)

Clopidogrel - may reduce antiplatelet effect)

Question 13

What drug class is Loperamide?

Answer 13

Antimotility

Question 14

How does loperamide work?

Answer 14

Is an agonist to the opioid mu receptors in the myenteric plexus of the large intestine. This reduces the tone in the large intestine muscles inhibiting peristalsis slowing motility

Question 15

What are side effects of Loperamide

Answer 15

Abdominal cramps
Dizziness
Flatulence
Headaches
Nausea

Paralytic ileus!!!

Question 16

What are contraindications to Loperamide?

Answer 16

Avoid in any kind of Colitis or if there is suspicion of infective diarrhoea

Question 17

What is important to communicate to patients about loperamide?

Answer 17

Not to be given to children under 4

Maintain adequate fluids

Question 18

Mesalazine (5 ASA) drug class?

Answer 18

Aminosalicylates

Olsalazine, Sulfasalazine, Balsalazide

Question 19

how does Mesalazine work?

Answer 19

Inhibit mucosal production of arachidonic acid metabolites such as prostaglandins. Reducing colonic inflammation

Question 20

What is Masalazine used

Answer 20

Crohns and Ulcerative colitis

Question 21

What are side affects of Mesalazine?

Answer 21

GI upset (diarrhoea, nausea, vomiting, abdominal pain)

Acute pancreatitis!!
Agranulocytosis!!
Renal dysfunction!! (interstitial nephritis, nephrotic syndrome)

Question 22

What is an important side effect of Sulfasalazine?

Answer 22

Lupus erythematosus-like syndrome

Question 23

When is Mesalazine Contraindicated?

Answer 23

Complete contradiction in Renal impairment

elderly, pregnancy and breastfeeding, patients with a history of asthma

Question 24

What are interactions of Aminosalycates?

Answer 24

Lactulose (reduces efficiency of 5 ASA)

Azathioprine (increased risk of leucopenia)

Mercaptopurine (increased risk of leucopenia)
Digoxin (absorption of digoxin may be reduced,)

Question 25

What is the follow up for Aminosalycates?

Answer 25

FBC, LFTs, ESR, CRP, U+E should be checked monthly for the first 3 months then 3 monthly thereafter (U+E annually unless theres some renal impairment)

Question 26

How would you check that blood dyscrasia wasn't occurring?

Answer 26

apart from checking bloods asking about oral ulceration/sore throat, unexplained rash or unusual bruising at every consultation.

Question 27

What is important to communicate to patients about aminosalycates?

Answer 27

Report any unexplained bleeding, bruising, purpura, sore throat, fever or malaise that occurs during treatment. Sulfasalazine may cause yellow-orange discoloration of skin, urine and other body fluids.

Question 28

What are the three types of laxatives

Answer 28

Bulk forming Osmotic Stimulant

Question 29

What is an example of bulk forming laxatives

Answer 29

Fibrogel

Question 30

How do bulk forming laxatives work

Answer 30

polysaccharide polymers which are not broken down in the upper GI tract. They increase stool volume. This activates the stretch relfex which stimulates peristalsis.

Question 31

What is an example of Osmotic laxatives?

Answer 31

Lactulose

Question 32

How do Osmotic laxatives work?

Answer 32

Solutes which are not absorbed producing an osmotic gradient within the bowel. Water moves into the lumen and speeds the transfer of gut contents through the small intestine This softens the stool and increases the distension of the lumen activating the stretch relfex which stimulates peristalsis.

Question 33

What is an example of Stimulant Laxatives

Answer 33

Senna

Question 34

How do stimulant laxatives work?

Answer 34

increase electrolyte and water secretion by the GI mucosa and to increase peristalsis. Senna is an anthroquinone stimulant laxative which directly stimulates the myenteric plexus leading to increased peristalsis and defecation.

Question 35

When would you specifically use lactulose?

Answer 35

In hepatic encephalopathy

Question 36

What are side effects of laxatives?

Answer 36

Abdominal distension and cramps Flatulence and Diarrhoea Electrolyte disturbances!!

Question 37

What are contraindications to Laxatives

Answer 37

Lactulose in patients who are lactose intolerant Avoid in intestinal obstruction or perforation. In severe inflammatory bowel disease and severe dehydration

Question 38

What is important to communicate to patients?

Answer 38

Explain to patients that they should drink plenty of fluids while taking laxatives to avoid dehydration and/or bowel obstruction. Patients should also maintain a healthy diet that includes fiber, fruit and vegetables. Osmotic and bulk-forming laxatives won't work immediately, take 2-3 days to reach their full effect.