Flashcards in 13.1 GI Motility Drugs Deck (50):
What can cause vomiting?
Problems with the vestibular system
Drug Induced - Post Op, Chemotherapy
Unpleasant Stimuli - Smells
Infections - Salmonella
What areas of the brain are involved in vomiting?
The Area Postrema
The Medullary Centres
The Vestibular Areas
What Neurotransmitters are involved in vomiting?
What are the 4 classes of Drug we use to treat vomiting?
ACh (muscarinic) antagonists
How do D2 antagonists work?
When are they used?
Act on the area postrema
Post Operations, if GI cause, Chemotherapy, Migraines
It can increase gastric emptying
Use in acute cases e.g for Parkinsons Disease medication
ADRs of D2 antagonists?
Gynacomastia (increased prolactin)
What are the stages of vomiting?
Stimulation of the Vomiting Centre - Area Postrema
Warning Signs - lightheaded, fast breathing, feel hot/sweaty, pale
Glottis closes, Soft Palate raises, pyloric sphincter contracts
Diaphragm and abdominal muscles contract, Cardia Relaxes
What is metoclopramide?
Oral, IM, IV
Half life of 4 hours
What is Domperidone?
Doesn't cross BBB
Extensive 1st Pass Metabolism
How do 5HT antagonists work?
They work on the area postrema and periphery
They prevent vagal stimulation
ADRs of 5HT antagonists?
Example of a 5HT antagonist
How do Histamine antagonists work?
Acute Cases e.g. MI
How do ACh antagonists work?
Use in travel sickness
Short Half Life
Take 30 mins to take effect
ADRs of Histamine Antagonists?
ADRs of ACh antagonists?
Can become tolerant
Can cause systemic anti-muscarinic effects
What drugs do you use to treat constipation?
Bulk Forming Laxatives
How do you remember the 4 Constipation Drugs?
Which treatments do you use if stool is found to be hard
Stool Softener (Faecal Softeners)
What laxative should you use if there is soft stool?
What lifestyle recommendations would you make to someone with constipation?
Five a Day
What conditions can cause constipation?
Which Drug do you not use if dehydrated?
Bulk Forming Agents - ispagula
Bulk Forming Agents - MoA?
Insoluble vegetable fibre, not absorbed, distends the intestine, stretch receptors causing peristalsis
It also draws H20 into the bowel, to distend as well
Bulk Forming Agents - When?
In pregnancy - it is safe!
Takes a few days to work and bring bowel function back to normal
Bulk Forming Agents - ADRs?
Bulk Forming Agents - Example
Bulk Forming Agents - Contraindications
Faecal Softeners - MoA and Example
Stay in the bowel, lubricate and soften stool
Faecal Softeners - When use?
If cannot tolerate fibre
Faecal Softeners - Contraindicated
Faecal Softeners - Why not very good?
Not always effective
Osmotically Active Laxatives - MoA?
Mg or Na Salts draw water into the bowel, distends the bowel causing peristalsis
Osmotically Active Laxatives - When use?
Instant relief needed
Osmotically Active Laxatives - PK
Lactulose - liver failure
Macrogols - helps dehydration
Osmotically Active Laxatives - ADRs
Can cause obstruction
Stimulant Laxatives - MoA
Irritate the bowel mucosa, stimulates peristalsis and H2O to go into the bowel
Stimulant Laxatives - Examples?
Stimulant Laxatives - When Use?
Overnight - takes 6/8 hours
Stimulant Laxatives - Contraindicated
Not Long Term - melanosis coli
Stimulant Laxatives - ADRs
How do you treat diarrhoea?
Drug treatments treat the symptoms not the cause
Treat underlying cause
Lifestyle Advice - no caffeine
Manage fluids and electrolytes
What drug classes would you treat diarrhoea with?
Anti-motility - opioids
Bulk Forming Agents
Bile Acid Sequestants
Anti-Motility Drugs - MoA?
Act on Opioid receptors on the bowel to reduce movement
Anti-Motility Drugs - Containdicated
IBD - Causes Toxic Megacolon
Anti-Motility Drugs - Positives?
Increase Anal Tone
Reduce Reflex to Defaecate
Anti-Motility Drugs - When use?
Bulk Forming Agents, why use in diarrhoea?
Creates a more formed stool
When do you use Bulk Forming Agents?