GI and Hepatic

Question 1

antacids

Answer 1

neutralise excess acid; raise pH; OTC

SEs: Mg » diarrhoea, Al » constipation, sodium » belching, calcium » gastrin; alter pH » altered absorption of other drugs

Question 2

H2 antagonists (‘tidines’)

Answer 2

inhibit PP via decreased ACh; best at night (H most prominent); relapse high; OTC

SEs: relapse, diarrhoea, rash

Question 3

PPI (‘prazoles’)

Answer 3

direct irreversible inhibition of PP (H+/K+-ATPase); decrease acid >90%; omeprazole = OTC

SEs: campylobacter, achlorydia, CAP/HAP, electrolytes (hypoMg/Na), C. diff, osteoporosis

Question 4

Misoprostol

Answer 4

PGE1 analogue » inhibited PP; often NSAID co-prescription (prevent ulcers)

SEs: uterine contraction, increased cAMP

Question 5

Management

Answer 5

non-ulcer: antacid/H2A
ulcer: PPI
H. pylori ulcer: PPI + 2ABx (clarithro +metronidazole/amox) 1/52; for H/ pylori)
GORD: lifestyle and pharma
NSAID PPx: PPI or misoprostol

Question 6

constipation management

Answer 6

osmotic laxative (lactulose): increase water 
Mg
bulking agents (cellulose): ^mass = ^peristalsis
stimulant laxatives (senna): ^ motility but cramps risk

Question 7

diarrhoea management:

Answer 7

loperimide (no BBB; enterohep recycling): hyperpolarise = decreased ACh = decreased motility
codeine (+analgesia): constipation = normal SE
ABx (if GE): only if infective
anti-muscarinics
stop offending drugs

Question 8

IBS management

Answer 8

symptomatic for d/c (lact/lop)
antispasmodics (buscopan): anti-Ch/motility
antimuscarinics (mebeverine): SM relax
motility agents (domperidone -DA): sphincters (less reflux, more emptying)
metoclopramide: local effect on GIT
diet: soluble fibre (avoid insoluble)

Question 9

IBD management

Answer 9

5-ASA (reduced LT and prostanoids, free radicals, neutrophil chemotaxis); sulphasalazine (colonic flora converts), mesalazine (pH converts); MAINT

prednisolone (anti-inflamm, immosupp); budesonide = poorly absorbed » less systemic SEs; REMISSION

aziathioprine, cyclosporin, MTX (immunosuppressants); STEP UP
*MTX = WEEKLY dosing

infliximab (TNF-a inhib); STEP UP

Question 10

Liver failure symptom management

Answer 10

vitamin deficiency: pabrinex, thiamine, multivitamin

jaundice: cholecystyramine
pruritis: menthol cream, anti-H, opioid antagonists

ascites: amiloride (K+-sparing), spironolactone, loop diuretic; stop NSAIDs, corticosteroids, and antacids (if possible

encephalopathy: ABx
impaired coag: vitamin K

gastric bleeding: PPI/anti-H
varices: vasopression, beta-blocker

Question 11

liver dysfunction effects

Answer 11

altered ADME: enzymes, ascites, hypoalbuminaemia, biliary obstruction
constipation, sedation, bleeding risk, sodium, fluid/electrolyte balance, nephrotoxicity
PARACETAMOL
check OTC and herbals

Question 12

Paracetamol poisoning

Answer 12

activated charcoal: stops absorption if given within 1h
n-acetyl cysteine: increases glutathione; effective if within 8h
check paracetamol levels (treatment line)

Question 13

N&V

Answer 13

• CYCLAZINE: H1 antagonist (traditional » drowsy SE); not long-term (habit forming); first line
  - ONDANSETRON: 5HT antagonist; good for CXT/post-op n&v
  - HYOSCINE: anti-cholinergic; used for travel sickness; SE: dry mouth, blurred vision, constipation, urinary retention, cognitive impair
  * same for TCA and ipatropium (anti-cholinergics)
  - PROCHLORPERAZINE: dopamine, ACh, and histamine antagonism; buccal preparation; good for Meniere’s and migraine; SE: extrapyramidal
  * chlorpromazine: related antipsychotic
  - METOCLOPRAMIDE: pure dopamine-antagonist; passes BBB; SE extra-pyramidal (PD), dystonia (spasticity e.g. eyeball rolling; young and female ^risk)
  * dystonia: stop drugs and give anticholinergic (ACh and DA in balance; DA decreased » increased ACh » dystonia)
  - DOMPERIDONE: dopamine antagonist; doesn’t pass BBB; safer in PD; PO only; also used for motility (e.g. IBS)