Antidiarrheals and laxatives - Ch 84 and 83 Flashcards
What drugs alter the motility of the GI tract?
Antidiarrheal drugs
Antispasmodic drugs
Laxatives/purgatives
What do Antidiarrheal drugs and Antispasmodic drugs do?
Decrease motility or which decrease smooth muscle tone
What do laxatives/purgative sod?
Accelerate the passage of food through the intestine
What is acute diarrhea?
Sudden onset in a previously healthy perosn
3 days - 2 weeks
Self-limiting
Resolve without sequelae
What are causes of acute diarrhea?
Microbial
Drug-induced
Nutritional
What is chronic diarrhea?
Lasts for more than 3 weeks
Recurring passage of diarrhea stools, fever, loss of appetite, nausea, vomiting, weight loss and chronic weakness
What are causes of chronic diarrhea?
Tumours
Diabetes
Hormonal (Hyperthyroidism, Addison’s disease)
IBS
What are some antidiarrheal drugs?
Opioids
Adsorbents
Anticholinergics (antispasmodic)
What is antidiarrheal opioids mechanism of action?
Activate opioid receptors in GI tract
-Decrease bowel motility
-Increasde bowel transit time
-Allows more time for water and electrolytes to be absorbed
-Decrease secretions and increase fluid absorption
Examples of opioid antidiarrheals?
Loperamide (Imodium)
Others: diphenoxylate, paregoric, opium
tincture
Describe loperamide?
Poorly absorbed
Poor access to CNS
Adverse effects associated with antidiarrheal opioids?
Excessive doses can lead to typical opioid drug effects
What do Adsorbents do?
Coat the walls of the GI tract
Bind to the causative bacteria or toxin, which is then eliminated through the still
Inhibit intestinal secretions
Examples of adsorbents?
Bismuth subsalicylate (Pepto-bismol)
Activated charcoal
What is Bismuth subsalicylate also used fro?
Relief of stomach acid symptoms
What adverse effects are associated with Bismuth subsalicylate?
Constipation
Dark stools and tongue
Metallic taste
Blue gums
Do not give Bismuth subsalicylate to who?
Children younger than age 16 or teenagers with viral infections e.g, chicken pox
-Reye’s syndrome
What is the mechanism of action of antidiarrheal anticholinergics?
Antagonist at cholinergic receptors
Decrease diarrhoea muscle cramping
Examples of antidiarrheal anticholinergics?
Atropine
Scopolamine (hyoscine)
What are laxatives mechanism of action/
Bulk forming (1-3 days)
Osmotic (hyperosmotic; dose dependant)
Fecal softener (emollient; 1-3 days)
Stimulant (6-12 hours)
*All laxatives lead to softer stools
Do not use laxatives if you have a ?
Bowel obstruction
Overuse/absuse of laxative scan cause?
Atonic colon -reduced muscular activity (lazy colon)
Dependency sort of
What are bulk forming laxatives?
High fibre substances (non-digestable material)
Absorbs water present in lumen to increase bulk
Distends bowel to initiate reflex bowel activity
Examples of bulk forming laxatives?
Methylcellulose (citrucel)
psyllium (Metamucil)
Polycarbophil
Bulk forming laxatives can also provide relief for what?
Diarrhea
What are osmotic laxatives?
Non-absorbable compounds or salt solutions that draw water into intestinal lumen
What can osmotic laxatives cause?
Substantial Water loss
-Dehydration
What are the types of osmotic laxatives?
Hyperosmotic compounds
Salines (salt solutions)
What do hyperosmotic compounds do?
Increase fecal water content
Bowel distention
Increased peristalsis and evacuation
Examples of hyperosmotic compounds?
Lactulose
polyethyleneglycol (Restoralax)
sorbitol
glycerin (enema/suppository)
What do salines do?
Increase osmotic pressure within the intestinal tract causing more water to enter the intestines
Bowel distension, increased peristalsis and evacuation
examples of saline laxatives?
magnesium sulfates
Magnesium hydroxide
magnesium citrate
sodium phosphate enema (Fleet)
For constipation how are osmotic laxatives administered?
low doses
6-12 hours
For diagnostic and surgical preps how are osmotic laxatives administered?
High doses
e.g, water stool in 2-6h for a clean colon
Examples: PEG + Na/Mg salines (PegLyte)
What do fecal softeners do? (emollients or surfactants)
Promote more water and fat ins tools
Lubricate the fecal material and intestinal walls
Examples of fecal softeners?
Stool softeners: decussate sodium (enema)
Lubricants: mineral oil
enema options
What do stimulant laxatives do?
Increases peristalsis via intestinal nerve stimulation
Increase fluid secretion into intestine
Examples of stimulant laxatives?
Senna (enema/suppository options)
cascara
bisacodyl (synthetic; enema/suppository)
castor oil (only for rapid GI cleansing)
Because opioids cause constipation what is used to prevent it?
Stimulants and fecal softener
Clients taking bulk forming laxatives should do what?
Take with at least 240mL or water (full glass)
prevents oesophageal obstruction
Clients should not take laxative sit they are experiencing what?
Nausea
Vomiting
and/or abdominal pain
