Pharma 13.2 - Gut Motility and Laxatives Flashcards Preview

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Flashcards in Pharma 13.2 - Gut Motility and Laxatives Deck (12):

What 2 plexuses form the enteric nervous system and where are they located?

The myenteric plexus - between the outer longitudinal and middle circular muscle layers. The submucous plexus - on the luminal side of the circular muscle layer.


What 4 classes of drugs are used for their effects on GI motility?

Motility stimulants. Antispasmodics. Laxatives. Antidiarrhoeals.


What are the 2 classes of antispasmodic drugs?

Antimucsarinics. Drugs that act directly on smooth muscle.


Give 3 examples of antimuscarinic antispasmodics. What is their mechanism of action? 3 indications? 4 contraindications? 1 ADR?

Atropine, propantheline, dicyclomine. MoA - Inhibition of parasympathetic activity causing smooth muscle relaxation. Indications - Non-ulcer dyspepsia, IBS, diverticular disease. Contraindications - GORD (LOS relaxation), angle-closure glaucoma, myasthenia gravis, paralytic ileus, prostatic enlargement. ADRs - anticholinergic effects.


Give 2 examples of motility stimulants. 2 indications?

Domperidone, metoclopramide. Indications - GORD, gastric stasis.


Name 4 types of laxative.

Bulk forming.



Faecal softeners.


Give 2 examples of bulk-forming laxatives.

What is their mechanism of action?

1 indication?

4 contraindications?

3 ADRs?

Methylcellulose, ispaghula husk.

MoA - Increasing the volume of non-absorbable solid residue in the gut to distend the colon.

Indications - Constipation (small hard stools).

Contraindications - Dysphagia, intestinal obstruction, colonic atony, faecal impaction.

ADRs - Flatulance, abdominal distension, GI obstruction.


Give 2 examples of osmotic laxatives.

What is their mechanism of action?

2 indications?

1 contraindication?

3 ADRs?

Lactulose, saline purgatives.

MoA - poorly absorbed compounds which increase the water content of the bowel.

Indications - Constapation, hepatic encephalopathy.

Contraindications - Intestinal obstruction.

ADRs - Flatulance, cramps, abdominal discomfort.


Give 4 examples of stimulant laxatives.

What is their mechanism of action?

3 indications?

1 contraindication?

2 ADRs?

Senna, danthron, bisacodyl, sodium picosulphate.

MoA - Increase peristalsis and water and electrolyte secretion into the bowel

Indications - Constipation, bowel evacuation prior to procedures.

Contraindications - intestinal obstruction.

ADRs - abdominal cramp (short term), nerxe plexus damage and atonic colon (long term)


Give 2 examples of faecal softeners.

What is their mechanism of action?

4 indications?

1 contraindication?

2 ADRs?

Liquid paraffin, docusate sodium.

MoA - Softening and lubricating faeces.

Indications - Constipation, faecal impaction, haemmorhoids, anal fissures.

Contraindications - age < 3

ADRs - paraffin can impare fat soluble A&D vitamin absorbtion and parrafinomas


Give 2 examples of opiate-like antimobility drugs.

What is their mechanism of action?

1 indication?

2 contraindications?

5 ADRs?

Loperamide, codine.

MoA - Act on opiate receptors in the myenteric plexus to increase tone and rhythmic contraction, lessening propulsive activity and secretion.

Indications - Ajunctive to fluid and electrolyte replacement.

Contraindications - Diarrhoeal conditions (e.g. UC), Children.

ADRs - Nausea, vomiting,  abdominal cramps, constipation, drowsiness.


What are 3 approaches to treating severe acute diarrhoea? 

What is the preferred course?

Maintenance of fluid and electrolyte balance(prefered)/oral rehydration therapy.

Use of antimicrobials.

Use of opiate-like antimobility drugs.