Antidiarrhoeals: drugs used in diarrhoea Flashcards
List out ACUTE antidiarrhoeal agents
- opioid agonists
- colloidal bismuth compounds
- intestinal adsorbents
- lyophilizate of killed Lactobacillus acidophilus
List out CHRONIC antidiarrhoeal agents
- bile salt-binding resins
- somatostatin-like peptides
What type of antidiarrhoeal agents is usually used for Traveler’s diarrhoea?
acute antidiarrhoeal agents
What type of drug is 1st line for rapid symptomatic relief of diarrhoea?
opioid agonists
Examples of opioid agonists
- loperamide
- diphenoxylate + atropine
Mechanism: Opioid agonists increase _________
colonic transit time (the amt of time that it takes for a substance to move through your colon)
Main concerns of opioid agonists
- diphenoxylate: potential for CNS effects including addiction & abuse —long term use can lead to dependence
To discourage diphenoxylate overdose, use ______
atropine
When tongue & stools turn black, what type of drug did the patient most likely take?
colloidal bismuth compounds
Examples of colloidal bismuth compounds
- bismuth subsalicylate
- bismuth subcitrate potassium
Mechanisms of colloidal bismuth compounds
- bismuth compounds:
- also used as
bismuth subsalicylate:
- bismuth has antimicrobial effect & binds enterotoxins which has benefit for treating traveller’s diarrhoea
- also used as mucosal protective agents in acid-peptic diseases (eg. peptic ulcers)
bismuth subsalicylate:
- rapid dissociation in stomach allowing absorption of salicylate
- salicylate inhibits intestinal prostaglandin production & chloride secretion
- reduces stool frequency & liquidity in acute infectious diarrhoea
Examples of intestinal adsorbents and elab
- kaolin: naturally occurring hydrated Mg aluminium silicate clay
- diosmectite: a Mg and Al silicate clay
- pectin: indigestible carbohydrate derived from apples
Mechanisms of intestinal adsorbents
- absorb bacteria, bacterial toxins, fluid
- decrease stool liquidity (forms solid stool mass)
Major concerns of intestinal adsorbents
- constipation
- can bind to and inhibit absorption of other meds: should not be taken within 2hrs of other meds
Example of lyophilizate of killed Lactobacillus acidophilus
lacteol fort (oral capsule or powder mixed with water)
For lyophilizate of killed Lactobacillus acidophilus, preparation contains __________ Lactobacillus acidophilus
heat-inactivated
Mechanism of lyophilizate of killed Lactobacillus acidophilus
- adheres onto the surface of intestinal cells and normalises intestinal flora by competitively excluding invasive bacteria
Main concerns of lyophilizate of killed Lactobacillus acidophilus
- important to maintain hydration
- contraindicated in patients with lactose intolerance as formulation contains lactose monohydrate
Examples of bile salt-binding resins
- colestyramine
- colestipol
- colesevelam
Mechanisms of bile salt-binding resins
- they are normally absorbed in the __________
- Crohn’s disease leads to _______ of bile salts, and thus results in _________________
- they bind to bile salts alleviating diarrhoea caused by _____________
- bile salts are normally absorbed in the terminal ileum
- Crohn’s disease leads to malabsorption of bile salts resulting in colonic secretory diarrhoea
- bind to bile salts alleviating diarrhoea caused by excess fecal bile salts
Main concerns of bile salt-binding resins
- bloating, flatulence, constipation, fecal impaction
- exacerbation of malabsorption of fat if underlying deficiency is present
- can bind to and inhibit absorption of other meds: should not be given within 2hrs of other drugs
Examples of somatostatin-like peptides
- octreotide
- subcutaneous injection and IM depot formulations
Mechanisms of somatostatin-like peptides:
1. mimics _________ released in the GI tract, pancreas and from the hypothalamus in the brain
- wide- spread physiological effects:
- _________ of release of various transmitters & hormones (eg. gastrin, VIP, 5-HT)
- reduces ___________
- slows ______ and inhibits _________ - use for secretory diarrhoea caused by GI and neuroendocrine tumours
eg. ______ and ___________
- mimics sometostatin hormone
- wide- spread physiological effects:
- inhibition of release of various transmitters & hormones (eg. gastrin, VIP, 5-HT)
- reduces intestinal and pancreatic secretions
- slows GI motility and inhibits gallbladder contraction - use for secretory diarrhoea caused by GI and neuroendocrine tumours
eg. carcinoid tumour and vasoactive intestinal peptide-secreting (VIP) tumour
Major concerns of somatostatin-like peptides:
- impaired pancreatic secretion can cause _______, which can lead to __________
- symptoms:
- formation of __________ in 50% of pts, rarely leading to ___________
- bradycardia
- impaired pancreatic secretion can cause steatorrhea, which can lead to fat-soluble vitamin deficiency
- symptoms: nausea, abdominal pain, flatulence & diarrhoea
- formation of gall sludge or gallstones in 50% of pts, rarely leading to acute cholecystitis
Prolonged treatment with somatostatin-like peptides can result in _________
hypothyroidism
When is activated charcoal used?
and how does it help?
emergency;
certain types of poisoning;
helps to prevent poison from being absorbed from the stomach into the body
Activated charcoal should not be used long-term as in interferes with _____________ and __________.
absorption of nutrients and absorption of other drugs
Main concerns of colloidal bismuth compounds
- harmless blackening of stools– which may be confused for GI bleeding
- prolonged use may rarely produce bismuth toxicity, leading to encephalopathy (ataxia, headaches, confusion, seizures)
- avoid in patients with renal insufficiency
