GI

Question 1

H2 Antagonists: Mechanism of Action

Answer 1

Block histamine receptor on parietal cells. Usually histamine activates the proton pump. There are alternate mechanisms so they are not as completely suppressive as PPIs

Question 2

H2 Antagonists: Indications

Answer 2

PUD, GORD, Dyspepsia

Question 3

H2 Antagonists: Side effects

Answer 3

Generally well tolerated, diarrhoea, constipation, headaches

Question 4

H2 Antagonists: Interactions and Warnings

Answer 4

No major interactions
Really excreted, so reduce dose in renal impairment
Can mask signs of gastric cancer

Question 5

H2 Antagonists: Prescribing

Answer 5

Short term use = OTC
No monitoring
Therapy is guided by symptoms

They have generally been superseded by PPIs, but they do have a faster onset

Question 6

PPI: Mechanism of Action

Answer 6

Irreversibly inhibit H+/K+ATPase in parietal cells so reduced acid production

Question 7

PPI: Indications

Answer 7

First line therapy for PUD, GORD, dyspepsia

H.Pylori eradication, as part of triple therapy

Question 8

PPI: Side Effects

Answer 8

GI Disturbance, headaches, some evidence of increases C.diff risk

Question 9

PPI: Interactions and Warnings

Answer 9

Omeprazole can decrease the efficacy of clopidogrel. Other PPIs have less of an effect.
They can mask the symptoms of GI cancer
Can increase the risk of osteoporosis

Question 10

PPI: Prescribing

Answer 10

Oral or injectable available

Question 11

Mesalazine: Mechanism of Action

Answer 11

It is an aminosalycilate drug. It acts be releasing 5-ASA. Its precise mechanism is unknown, but it acts locally on the gut and has anti-inflammatory and immunosuppressive effects.

Question 12

Mesalazine: Indications

Answer 12

Mild to moderate UC (First line drug)

Question 13

Mesalazine: Side Effects

Answer 13

Nausea, dyspepsia, headache

Rare but serious: renal impairment, leukopenia, thrombocytopenia

Question 14

Mesalazine: Interactions and Warnings

Answer 14

Tablets with a pH sensitive coating may be affected by changes in gastric pH
ASPIRIN ALLERGY!

Question 15

Mesalazine: Prescribing

Answer 15

Oral or suppository
Renal function should be checked for safety
Efficacy is guided by symptoms

Question 16

Loperamide: Mechanism of Action

Answer 16

It is an opioid and is chemically similar to pethidine. However, it does not penetrate the CNS so has no analgesic properties. It agonises GI mu-opoid receptors. It slows peristaltic contractions and increases anal tone. The increased transit time means more water can be reabsorbed.

Question 17

Loperamide: Indications

Answer 17

Diarrhoea, usually viral gastroenteritis or IBD

Question 18

Loperamide: Side Effects

Answer 18

Predictable: constipation, cramping, flatulance

Question 19

Loperamide: Interactions and Warnings

Answer 19

Should be avoided in acute ulcerative colitis (inc. risk of toxic megacolon and perforation). Should be avoided in C.Diff and with bloody diarrhoea (could be ETEC) because of the risk of HUS.

It has no clinically significant interactions.

Question 20

Loperamide: Prescribing

Answer 20

Can be purchased OTC (probably will be cheaper for patient)
Monitored by symptomatic relief
Makes sure to mention it does not treat underlying cause.