constipation and ibs

Question 1

what are the causes of constipation

Answer 1

• poor diet
• drug therapies (pain killeers and anaesthetics)
• lack of exercise
• perceived constipation
• IBS

Question 2

what are the red flags of constipation

Answer 2

• new onset constipation especially over the age of 60
• anemia
• abdominal pain
• weight loss
• blood in the stool

Question 3

what are the problems with constipation

Answer 3

• haemorrhoids
• annal fissures
• recta; prolapse
  faecal impaction

Question 4

what are the types of laxatives

Answer 4

• bulk forming laxatives - they act by increasing feacal bulk, stimulate peristalsis and are considered the safest agents and are suitable for long term use. (need to be taken with water)
  example- methylcellulose (synthetic) bran and vegetable fibre (natural)

osmotic laxatives - partially soluble, but not absorbable, draw water into bowel, effects in 1-3 hrs. good for bowel clearing.
not good for patients with heart disease, renal failure, high bp, should not use
example - magnesium salts, sodium salts, lactulose, sorbitol, polyethylene glycol

irritant laxatives - they increase secretion of water and electrolytes, stimulate enteric neurones in myenteric plexus to stimulate
examples; senna, co- danthramer and co- danthrusates (these are only for terminally ill patients), bisacodyl, sodium picosulphate.

stimulant laxatives
senna - activated in colon by bacteria. active compound absorbed and stimulates myenteric nerves
good for short term use on drug induced constipation
Bisacodyl - stimulates rectal mucosa, for oral administration it works in 6-8 hrs, for suppositories works in 15 mins
sodium picosulphate - this is a prodrug

Question 5

what are the side effects of stimulant laxatives

Answer 5

senna - abdominal cramps. damaged nerves loss of gastrointestinal muscular tone

bisacodyl - fluid/electrolyte imbalance

Question 6

lubricants or stoool softeners

Answer 6

• active ingredients in laxatives is a chemical called docusate
  this works by detergent action, lowers surface tension, break up stool, stimulate fluid accumulation

this is used to prevent constipation

example ; docusate sodium

Question 7

prokinetic drugs; 5- HT4 agonists

-enteric neurones
- epithelial

Answer 7

prucalopride is a highly selective 5- HT4 agonist

5-HT4 agonists act on enteric neurones to stimulate motility and epithelial cells to stimulate secretion

this is used for chronic constipation

Question 8

management of constipation

Answer 8

short term
- dietary changes
- bulk forming laxatives
- osmotic laxatives
- then add stimulant laxatives

opioid induced constipation
- osmotic laxatives and stimulant laxatives
- use Naloxegol
- methylnaltrexone

Question 9

what is ibs

Answer 9

umbrella term for a group of functional bowel disorders

• chronic abdominal complaint with no obvious biochemical or physiological abnormalities

symptoms
- abdominal pain
- bloating
- diarrhoea
- constipation
- functional dyspepsia
- bladder problems
- heartburn
- backaches

ibs can be divided into
ibs - d
ibs - c
ibs - m (mixed)
ibs - u (unclassified)

Question 10

ibs treatment

Answer 10

pain relief

antispasmodic medicine
- scopolamine (buscopan)
tricyclic antidepressants
- amitriptyline
pain relief
- paracetamol

motility remedies

anti diarrhoeal drugs
- loperamide
laxatives

Question 11

prokinetic drugs 2 - secretory agents

Answer 11

linaclotide
this is a guanylate cyclase agonist

increases cl- secretion into lumen
used to treat ibs c
promotes fluid secretion into lumen
blocks pain signalling