Ranitidine

Question 1

What is Ranitidine?

Answer 1

non-imadazole blocker of Histamine 2 receptors which mediate gastric secretion

Question 2

What class of drugs does Ranitidine belong to?

Answer 2

Hyperacidicty, reflux and ulcers

Question 3

What are examples of other drugs in the same class as Ranitidine?

Answer 3

Cimetidine
Simethicone
Bismuth trioxide
alginates
Famotidine

Question 4

What is Ranitidine indicated for?

Answer 4

• benign peptic ulceration
• chronic episodic dyspepsia
• treatment of NSAID-associated ulceration
• prevention of NSAID-associated duodenal ulcers
• GORD
• stress ulcer prophylaxis
• prevention of GI haemorrhage when ulcers present
• prophylaxis of acid aspiration in srugery and labour

Question 5

What is the mechanism of action of Ranitidine?

Answer 5

• Inhibits Histamine-2 receptors on parietal cells and suppresses acid secretion by

1) blocking ECL cells released by histamine from binding on parietal H2 receptors
2) other substances promoting acid secretion (gastrin and acetylcholine) have less effect on parietal cells when H2 receptors are blocked

Question 6

What is the role of ranitidine in therapy?

Answer 6

second line for patients with GORD (mild symptoms who have not responded to a 4-6 week trial with PPI)

or can be used adjunctive to PPI following discussion with specialist e.g. in patients with nocturnal symptoms unimproved following morning dosing with a PPI may benefit from 300mg ranitidine at night for up to 8 weeks

Question 7

What is the dose of Ranitidine given for benign peptic ulceration?

Answer 7

adult: 150mg bd or 300mg nocte for 4-8 weeks

Question 8

What is the dose of Ranitidine given for chronic episodic dyspepsia?

Answer 8

150mg bd, or 300mg nocte up to 6 weeks

Question 9

What is the dose of Ranitidine given for NSAID-assoc ulceration?

Answer 9

150mg bd or 300mg nocte for up to 8 weeks

in duodenal ulcer: 300mg can be given bd for 4 weeks for a higher healing rate

maintenance = 150mg nocte.

Question 10

What is the dose of Ranitidine given for prophylaxis of NSAID-assoc duodenal ulceration?

Answer 10

up to 150mg bd

Question 11

What is the dose of Ranitidine given for GORD?

Answer 11

Adult 150mg bd or 300mg up to 8 weeks

If mod-severe: 600mg OD in 2-4 divided doses for up to 12 weeks.

Long term treatment of healed GORD = 150mg bd

Question 12

What is the dose of Ranitidine given for prevention of GI haemorrhage when ulcers are present and in stress ulcer prophylaxis?

Answer 12

Adult: once injection has stopped, 150mg BD

Question 13

What are the relevant PD/PK parameters with Ranitidine use?

Answer 13

PK:

approx 50% bioavailability orally

15% bound to proteins

hepatically metabolised

Primarily excreted in urine

half life: 2.8-3.1 hours

Question 14

What are the cautions associated with Ranitidine use?

Answer 14

• may mask symptoms of gastric cancer
• cardiac rhythm disturbances (bradycardia with rapid IV admin)
• if renal impairment, use half normal dose if eGFR<50ml/min
• pregnancy B1: manufacturer advised to avoid unless essential, compatible with breastfeeding

Question 15

What are the adverse effects with Ranitidine use?

Answer 15

• diarrhoea,
• headache, dizziness
• rash (erythema multiforme and toxic epidermal necrolysis)
• blurred vision

Question 16

What are the relevant drug interacts with Ranitidine use?

Answer 16

Avoid concurrent use with histamine as Ranitidine blocks the effects of histamine

• markedly reduces ketoconazole exposure

Question 17

What are the alarm bells with Ranitidine use?

Answer 17

report new and worsening symptoms to the doctor

may have elevated LFTs, hepatitis, jaundice,

May mask gastric cancer symptoms - rule out before initiating treatment