GI DRUGS

Question 1

PROTON PUMP INHIBITOR
(Lanzaprazole, Omeprazole, Pantoprazole)

Answer 1

I: Treatment of peptic ulcer disease, reliefs dyspepsia + GORD, eradication of H.pylori
MOA: Irreversibly inhibits H+/K+- ATPase in gastric parietal cells. It suppresses gastric acid completely
SE: GI distrurbance, headache, prolonged PPI use can lead to hypomagnesaemia, worsening of hyponatraemia
KI: Omeprazole can ↓ efficacy of clopidogrel whereas lanzaprazole and pantoprazole do not interact.
CI: disguises the symptoms of GI cancer, can ↑ risk of fracture in elderly for prolonged courses
C: pts at risk of osteoporosis
M: Symptoms (peptic ulcer) + in prolonged use >1 year, check serum magnesium (hypomagnesaemia)

Question 2

H2 RECEPTOR ANTAGONIST
(Ranitidine)

Answer 2

I: Peptic ulcer disease, GORD, dyspepsia
MOA: Reduces gastric acid secretion. It does not entirely suppress gastric acid production
SE: Bowel disturbances - diarrohea / constipation, headache, dizziness
CI: disguise symptoms of gastro-oesphageal cancer
C: ↓ dose in renal impairment
M: PUD- repeat endoscopy to confirm healing

Question 3

ANTACIDS
(Gaviscon, Peptac)

Answer 3

I: GORD, dyspepsia
MOA: they work by buffering stomach acids. After reacting with the acid, they form a floating raft which seperates gastric content from the G-O junction to prevent mucosal damage. Alginates increase voscity of the stomach contents.
SE: Magnesium salts - diarrhoea. Aluminium salts - Constipation
KI: Reduces serum concentration of many drugs such as ACEi, ABX (tetracycline, cephalosporin, ciprofloxacin), bisophosphonates, digoxin, levothyroxine and PPI. It also increases the excretion of aspirin and lithium.
CI: Alginates should not be given in combination with thickened milk prep as it can lead to ↑ thick stomach content that causes bloating and abdominal discomfort
C: fluid overload, hyperkalaemia, renal failure , some preps contain sucrose which can worsen hyperglycaemia in pts. with diabetes
M: Symptoms (red flags - further investigations)

Question 4

Laxatives
(psyllium, polycarbophil, methylcellulose) Bulk
(Lactulose, Macrogol, Phosphate Enema) Osmotic
(Senna, Bisacodyl, Glycerol Supposutories, Docusate Sodium) Stimulant

Answer 4

Bulk:
I: Chronic constipation due to diet, lifestyle, recent surgery, medication
SE: intestinal blocking, itching, rash, dysphagia
CI: Hx hypersensitivity, partial obstruction of bowel, dysphagia, undiagnosed abdo pain

Osmotic:
I: constipation, faecal impaction, hepatic encephalopathy, bowel prep for surgery
SE: flatulence, abdo cramps, nausea, diarrohea, electrolyte disturbance
CI: should not be used in pts. with intestinal obstruction - risk of perforation
C: HF, ascites

Stimulant
I: constipation, faecal impaction
SE: Abdo pain, diarrohea, excessive use can lead to melanosis coli
CI: should not be used in pts. with intestinal obstruction - risk of perforation. Rectal preps avoided in haemorrhoids or anal fissures

M: Bristol stool chart

Question 5

METOCLOPROMIDE

Answer 5

I: treatment of nausea and vomiting including that associated with acute migraine,prevention of postoperative nausea and vomiting
SE: Asthenia, depression, diarrhoea; drowsiness, hypotension
CI: 3–4 days after GI surgery, epilepsy, GI haemorrhage, GI obstruction, GI perforation, phaeochromocytoma
C: Can mask underlying disorders such as cerebral irritation

Question 6

LOPERAMIDE

Answer 6

I: treatment of acute and chronic diarrhoea, faecal incontinence
SE: GI disorder, headache, nausea, dizziness
CI Active ulcerative colitis, antibiotic-associated colitis, bacterial enterocolitis
C: not recommended in children <12 years, hepatic impairment, pregnancy