H2-receptor antagonists and PPIs

Question 1

List the indications for H2-receptor antagonists

Answer 1

1) Peptic ulcer disease: treatment and prevention of gastric and duodenal ulcers and NSAID-associated ulcers
2) GORD

Question 2

What is zollinger-ellison syndrome and why are H2-receptor antagonists not recommended in this condition?

Answer 2

1) Gastrin-secreting tumour which causes overproduction of gastric acid, resulting in recurrent peptic ulcers
2) PPIs are more effective for treating this condition

Question 3

Outline the MoA of H2-receptor antagonists

Answer 3

Reduce gastric acid output as a result of histamine H2-receptor blockade

Question 4

What side effects can H2-blockers cause

Answer 4

1) Bowel disturbance (diarrhoea less often, constipation)
2) Headache
3) Dizziness

Question 5

Who should H2-blockers be used in caution with?

Answer 5

1) H2-blockers are excreted by the kidneys, so their dose should be reduced in patients with renal impairment.
2) Can disguise the symptoms of gastro-oesophageal cancer, so rule out any alarm features before prescribing

Question 6

Why might H2-blockers be used in obstetric patients at delivery?

Answer 6

Reduce the risk of acid aspiration

Question 7

What is one benefit of using H2-blockers compared to PPIs?

Answer 7

More rapid onset of effect- makes them a better choice for suppressing gastric acid production pre-operatively.

Question 8

When should ranitidine be administered?

Answer 8

Taken before, with or after food

Question 9

Outline the MoA of PPIs

Answer 9

Inhibit gastric acid secretion by blocking the proton pump of the gastric parietal cell

Question 10

Outline the MHRA important safety advice regarding the use of PPIs

Answer 10

1) Very low risk of subacute cutaneous lupus erythematosus (SCLE) in those taking PPIs which can occur months or years after exposure
2) Patient develops lesions in sun-exposed areas accompanied with arthralgia (pain in joints)

Question 11

If patients develop lesions in sun-exposed areas accompanied with arthralgia this can be an indication of SCLE. what advice does the MHRA suggest giving to patients? (4)

Answer 11

1) Avoid exposing skin to sunlight
2) Consider SCLE as possibility
3) Consider stopping PPI unless it is for a serious acid-related condition
4) In most people, symptoms resolve on PPI withdrawal

Question 12

List the common indications for PPIs (3)

Answer 12

1) Prevention and treatment of peptic ulcer disease, including NSAID-associated ulcers.
2) Symptomatic relief of dyspepsia GORD
3) Eradication of Helicobacter pylori infection

Question 13

list the important side effects caused by PPIs

Answer 13

1) GI disturbances and headache
2) Can cause clostridium difficile infection
3) Prolonged treatment can cause hypomagnesaemia which if severe can lead to tetany and ventricular arrhythmia.

Question 14

Explain why clostridium difficile infections are more likely to occur in patients taking PPIs

Answer 14

By increasing the gastric pH, PPIs may reduce the body’s host defence against infection

Question 15

Why should PPIs be prescribed in caution in those presenting with alarm features?

Answer 15

May disguise symptoms of gastro-oesophageal cancer- Gastric malignancy should be rules out before treatment

Question 16

1) What can prolonged courses of PPIs, especially at high doses cause in the elderly?
2) how can this be prevented?

Answer 16

1) Increase the risk of fracture. so use in caution in those at risk of osteoporosis
2) Patients at risk of osteoporosis should maintain an adequate intake of calcium and vitamin D

Question 17

what important interactions can PPIs cause?

Answer 17

Reduce the antiplatelet effect of clopidogrel by decreasing its activation by cytochrome P450 (prescribe lansoprazole and pantoprazole instead)

Question 18

How should PPIs be administered?

Answer 18

can be taken with food or on an empty stomach. They are best taken in the morning

Question 19

Outline the monitoring requirements for PPIs

Answer 19

measure serum magnesium levels before and during Prolonged treatment with PPI, especially when used with drugs that cause hypomagnesaemia or with digoxin

Question 20

why should patients undergoing investigation for H. pylori, have their PPI withed for 2 weeks prior to the investigation?

Answer 20

Increases the chance of a false-negative result.